Poster Presentation Abstracts

Click on the poster title to link to the poster pdf file, where available.

Molecular Gas, AGN Feedback and the Unusual Case of NGC 1266

Katey Alatalo (UC - Berkeley)

Leo Blitz (UC - Berkeley)
Timothy A. Davis (Oxford University)
Lisa M. Young (New Mexico Tech / NRAO)
Martin Bureau (Oxford University)
The ATLAS3D Team (Various)

NGC 1266 is an S0 galaxy that was observed in multiple wavelengths as part of the ATLAS3D effort which remarkably hosts about 109 solar masses of molecular gas and has a spectrum that exhibits extended wings of up to +/-400 km/s. High resolution CARMA observations have shed further light on this galaxy and revealed that the bulk of the gas is concentrated within 100pc of the nucleus. Combined with the presence of an AGN and molecular gas outflowing faster than vesc, this galaxy is an excellent candidate for AGN feedback. If so, it is the first example of molecular feedback into the IGM from a relatively normal galaxy. How the gas fell so deeply into the potential well, and the exact nature of the driving mechanism behind the expulsion of the gas remain mysteries.

High Resolution Methyl Cyanide and Carbon Monosulphide Observations of IRAS 18566+0408

Crystal Anderson (New Mexico Institute of Mining of Technology)

P. Hofner (New Mexico Institute of Mining and Technology)
D. Shepherd (National Radio Astronomy Observatory)
S. Schnee (National Radio Astronomy Observatory)
D. Meier (New Mexico Institute of Mining and Technology)
E. Araya (Western Illinois University)
S. Kurtz (UNAM Morelia, Mexico)
R. Cesaroni (Arcetri Observatory, Italy)

The formation process of massive stars remains a major topic in astrophysics, and whether mass accretion occurs through a disk is one of the key unanswered questions. Using single dish and interferometric observations we have established IRAS 18566+0408 as a candidate of a massive protostar containing a disk/jet system. The IRAS 18566+0408 region at a distance of 6.7kpc has a luminosity of several 104 Lsol, indicating the presence of massive stars. Dense molecular gas and the absence of strong radio continuum emission confirm this region as a source for massive star formation in a phase prior to the ultra/hyper compact H2 region phase. On 1000 AU scales, IRAS 18566+0408 is surrounded by a massive neutral torus and an ionized jet is seen perpendicular to the torus, with evidence for infall from 12CS(2-1). Also, at present 7mm dust continuum data provide strong evidence for a structure elongated perpendicular to the flow axis as expected for an accretion disk. We present preliminary results from CARMA observations of IRAS 18566+0408. We observed IRAS 18566+0408 using two classic molecular line tracers of accretion disks: CH3CN(5-4) and 13CS(2-1). Both molecular line tracers were detected as well as the K=0,1,2,3,4 components of CH3CN(5-4). We find the source to be resolved and the peak emission of 13CS(2-1) and CH3CN(5-4) to be offset to the northeast of the ionized jet. The kinematics of the lines indicate possible Keplerian rotation with a dynamical mass of at least 102 Msol. We also find the 13CS spectrum does not possess the redshifted component as seen in previous 12CS(2-1) observations. It is possible, that the emission from these molecular line tracers are predominately coming from a massive circumstellar disk (torus).

This project is partially supported by NSF grant AST-0908901

The transition between the atomic gas and the molecular gas in two cirrus clouds of the North Celestial Loop

Leo Barriault (Collège universitaire de Saint-Boniface)

Gilles Joncas (Université Laval) et al.

The infrared (IR) cirrus clouds observed at high Galactic latitude are excellent candidates to study the transition between the atomic gas and the molecular gas. Two potential sites of H2 formation have been discovered in the North Celestial Loop (l=135°,b=40°) through examining the far-IR--HI ratio and looking for an excess over that expected from an atomic medium. These sites are called the Spider and Ursa Major fields. The comparison between the IR excess map and the 12CO (J=1-0) data from the Five College Radio Astronomical Observatory (resolution = 45") shows that the IR excess peaks do not coincide with the 12CO peaks. The absence of coincidence is explained by (i) density too small to allow CO excitation, (ii) insufficient CO self-shielding or (iii) variations of the dust properties. The comparison between 12CO data and HI data from the Dominion Radio Astrophysical Observatory (resolution = 1') is in agreement with the models that predict CO formation where large velocity shears and turbulence dissipation are observed. OH observations of 108 locations over the two diffuse clouds from the Green Bank Telescope (resolution = 7') were analyzed. OH is a precursor molecule to CO and its formation requires H2. The coincidence between the OH emission peak and the IR excess peak indicates that OH could be a better tracer of H2 than CO in these low-density regions. 12CO (J=1-0) and 13CO (J=1-0) observations from the Institut de Radioastronomie Millimétrique and 12CO (J=2-1) observations from the James Clerk Maxwell Telescope (resolution=20") were analyzed on a small number of fields in both regions. Using a large velocity gradient model, we found smaller densities at the location of the IR excess peak while self-shielding should be efficient given the computed column densities.

VLA Ammonia and Spitzer Observations of the Class 0 Candidate Proto-Brown-Dwarf, IRAS 16253-2429

Mary Barsony (Space Science Institute)

Jennifer Wiseman (NASA/GSFC)
Raghvendra Sahai (NASA/JPL)
Grace Wolf-Chase (Adler Planetarium Astronomy Museum and U. Chicago)
David R. Ciardi (NASA Exoplanet Science Institute/Caltech)

The Wasp-Waist Nebula, so-called for its beautiful bipolar shape, was discovered by Spitzer's InfraRed Array Camera. A weak outflow, evident in CO J=3-2 and 2.12 micron H2 emission, had previously been detected from the ground. The central engine, IRAS 16253-2429, displays a Class 0 spectral energy distibution, and has a bolometric luminosity of just ~0.27 Lsol, at a distance of 119 pc. The sinuous, S-shaped flow was recently mapped with Spitzer's InfraRed Spectrometer (Barsony et al. 2010). The pure rotational H2 lines emitted by the shocked outflow gas reveal 1000K temperatures in low velocity Jump-type shocks, and the presence of weak magnetic fields (~3-10 microG) in the ambient gas, which has densities of 103-104 cm-3. We present integrated emission and intensity-weighted velocity maps of the ammonia (J,K)=(1,1) and (2,2) inversion transitions of the cold, low-mass molecular cloud core surrounding the central source. The data were acquired in the VLA's compact, DnC configuration, to maximimize sensitivity to the extended envelope, yielding a synthesized beam of 9.4"x6.8" (1175 AU x 850 AU at the source). Velocity resolution was 0.31 km/sec over a 40 km/sec band. Spitzer IRAC 8 micron imaging reveals the same core in absorption against the bright PAH emission of the background cloud. The ammonia emission coincides with the mid-infared absorption, revealing a flattened envelope of dense gas, with the NH3 emission peaking on either side of the central protostar, defining a line perpendicular to the outflow axis. Also apparent in the ammonia emission is an open outflow cavity to the northeast (and, to a lesser extent, to the southwest) cradling the lobes of the bipolar outflow cavities seen in scattered light at the shortest IRAC (3.6 micron and 4.5 micron) wavelengths. The Moment 1 velocity field shows no obvious, coherent, large-scale motion, as is typical for a pre-stellar core. However, there is a hint of a possible rotational gradient across the central equatorial region, connecting the two peaks in integrated emission as seen in the Moment 0 map. ALMA will be the ideal instrument to further investigate the internal kinematics and spatial distribution of the gas in the innermost regions of this nearby, very young, and very low-mass Class 0 source.

Detailed Temperature Map of the Taurus Molecular Cloud

Andrew Battisti (NRAO)

Megan Jones (University of Wisconsin-Madison)
Glen Langston (NRAO)

The Taurus Molecular Cloud (TMC) provides us with a rich environment to study astrochemistry. We used data taken with the K Band Focal Plane Array (KFPA) on the Green Bank Telescope (GBT) to measure ammonia NH3 (1-1) and (2-2) lines to produce a detailed temperature map of the cloud. The NH3 (2-2) line was below the noise level of the measurement and so we present only an upper limit temperature map. Much longer exposures of the cloud will be required to reveal the (2-2) line because of its extremely low temperature. We also created a procedure to detect linear molecules, such as the cyanopolynnes HC11N and HC13N, whose emission behavior is dependent on a rotational constant and a quartic centrifugal distortion constant. This procedure can scan over a range of values for these constants and would sum up all the regions in the spectra (i.e. 1-1, 2-2, etc.) in velocity space where the emissions lines would be and select out cases whose signal would add up to give a SNR greater than 3. This project used archived GBT data that had been combined to create much greater signal to noise ratio.

From GMC to dense core gas, the multiple gas components seen in extragalactic sources

Estella Bayet (University of Oxford)

Serena Viti (University College London)
David Williams (University College London)
Jesus Martin-Pintado (CSIC-DAMIR)
Sergio Martin (ESO-Chile)
Jeremy Yates (University College London)

To comprehend fully the star formation activity in galaxies, it is essential to study the various gas components which contribute to the star formation. The gas traced by the monoxide carbon lines currently put "on spot" by the large amount of Herschel data release is important to study, but it is far from sufficient and more emphasise has to be applied on other ions, atomic and molecular tracers of denser and warmer gas. Only a parallel astrochemical and astrophysical treatment, involving both observational data and state-of-the-art models can lead to major improvment of our understanding of star formation processes.

In my review, I will present such treatment, showing the latest observational data and up-to-date models (LVG, PDR, Chemical, radiative transfer codes) for reproducing extragalactic environments, first for a sample nearby galaxies. In this sample, I will present the physical and chemical properties (e.g. kinetic temperature, FUV radiation field, density, fractional abundances of 200 species...) that I have derived for the Giant Molecular cloud gas phase (Bayet et al., 2004, 2006) as well as for its warmer and denser phase, typical of dense cores (Bayet et al., 2008a, 2008b, 2009a, 2009b, 2010). I will show how these properties vary from a galaxy activity to another (i.e. starburst, AGN, CR-dominated, low-metallicity, ...) and present the key species in each type of gas and for each galaxy activity to observe with ALMA for increasing now our comprehension of the star formation at the smallest scales.

I will finish my talk by showing for the first time the preliminary physical and chemical properties of the gas observed in early-type galaxies, thought to be until recently ;SPMquot;red and dead' systems but which actually habor some star formation activity.

Coordinated Multi-Wavelength Interferometry and Spectroscopy of Mira Variables

David Boboltz (USNO)

M. Wittkowski (ESO)
I. Karovicova (ESO)
E. M. L. Humphreys (ESO)
M. D. Gray (JBCA)
C. de Breuck (ESO)

We present recent results from our coordinated multi-wavelength approach to the study of the extended atmospheres of Mira variables using the Very Long Baseline Array (VLBA), the Very Large Telescope Interferometer (VLTI) and the Atacama Pathfinder Experiment (APEX). Interferometric imaging and spectroscopy of the SiO maser emission toward Mira variables combined with interferometry at near near- and mid-IR wavelengths provides a unique probe of the star and its nearby circumstellar environment. The coordinated data are interpreted in the context of recent dynamic model atmospheres combined with a radiative transfer model of the dust shell and models for the propagation of SiO maser emission. The prospect of future observations with the eVLA and ALMA are also discussed.

The need for high spatial and spectral resolution observations in the study of low-mass binary protostars

Sandrine Bottinelli (IRAP (Toulouse, France))

Emmanuel Caux (IRAP/Université de Toulouse)
Claudine Kahane (IPAG/Université de Grenoble)
Cecilia Ceccarelli (IPAG/Université de Grenoble)
Valentine Wakelam (Laboratoire d'Astrophysique de Bordeaux)

The recent observations obtained by the HIFI instrument onboard Herschel towards star-forming regions has emphasized the importance of high-spectral resolution, which, for instance, allows us to obtain information on these highly dynamic regions (infall/outflow). Moreover, the ground-based spectral survey of the low-mass protostar IRAS16293-2422 (Caux et al. submitted) sheds a new light on the kinematics and hence on the nature of this binary protostellar object and makes it plain that models assuming a single source are not sufficient any more. Unfortunately, high spatial and spectral resolution data are very scarce towards binary protostars, and it is therefore difficult to improve our understanding and hence the modeling of this type of sources. The unprecedented capabilities of ALMA will allow us to study key molecules and search for new ones in several low-mass binary protostars, and will therefore help us to achieve a big leap in our understanding of the small-scale structure, chemistry and dynamics of these objects, thereby improving our knowledge of the low-mass star-formation process, and in particular of the interaction between the protostellar cores that formed from the collapse of a single cloud. We will present recent results obtained for IRAS16293-2422 (ground-based survey and HIFI observations), and some of the achievements that spectroscopic studies with ALMA will bring.

A debris disk around an F-type star resolved with Herschel at multiple wavelengths

Hannah Broekhoven-Fiene (University of Victoria)

Brenda Matthews (Herzberg Institute of Astrophysics)
John Qi (Herzberg Institute of Astrophysics)

Debris disks are composed of dust grains and planetesimals around main-sequence stars. The dust population is replenished by colliding planetesimals which were formed in the protoplanetary disk. The Herschel DEBRIS (Disk Emission via Bias-free Reconnaissance in the Infrared/Submillimetre) survey is a flux-limited survey of 446 nearby main-sequence stars designed to detect and characterize debris disks. It is unbiased to spectral type, age, metallicity, binarity and presence of known planets. Herschel's observing wavelengths and sensitivity promise to increase the number of known debris disk hosts. Its resolving power offers the ability to learn more on the structure of disks, as they have sizes of ~10-1000 AU.

The spatial information is of key interest because the observed spectral energy distribution (SED) of the dust has degeneracies between the grain properties and the disk size. As a result disk radii estimated from SED modelling (assuming blackbody grains) have been found to underestimate the radii determined from imaging. Therefore resolved images help to constrain dust properties. The multi-wavelength imaging also samples different grain populations at each wavelength. (Cooler grains dominate the emission more at longer wavelengths.) Finally, determining the spatial distribution of dust grains can point towards the location of the parent planetesimal population.

We will present resolved maps and surface brightness distributions at 100 and 160 micron (using PACS) showing the extended emission due to the disk, along with observations at 250, 350 and 500 micron (using SPIRE) of a known debris disk host. We will also show the SED which is sampled in the submillimetre for the first time.

Characterization of Turbulence from Submillimeter Dust Emission

Shadi Chitsazzadeh (University of Victoria )

Martin Houde (University of Western Ontario)
Roger Hildebrand (University of Chicago )
John Vaillancourt (NASA Ames Research Center)

We use the recent technique introduced by Houde et al.(2009) for studying the turbulent component of magnetic fields in molecular clouds to derive the structure functions of the unpolarized flux as well as that of the Q and U Stokes parameters of the polarized flux in OMC-1. The solutions for the structure functions to 350 micron SHARP polarization data of OMC-1 allow the determination of the corresponding turbulent correlation length scales. The estimated values for these length scales are approximately 9.4" +/- 0.1", 7.3" +/- 0.1", 12.6" +/- 0.2" (or 20 +/- 2, 16 +/- 2, and 27 +/- 4 mpc at 450 pc, the adopted distance for OMC-1) for the Stokes parameters Q and U, and for the unpolarized flux N, respectively. Our current results for Q and U are consistent with previous results obtained through other methods. We infer a weak coupling between the dust component responsible for the unpolarized emission N and the magnetic field B from the significant difference between the Q (or U) and N turbulent correlation length scales.

Gas and star-formation in the Cosmic Eye

Kristen Coppin (McGill University)

Mark Swinbank (Durham University)
Roberto Neri (IRAM)
Pierre Cox (IRAM)
Ian Smail (Durham) et al.

We have performed a detailed study of the gas and star-formation in a highly magnified Lyman-break galaxy (LBG) at z=3.07, by effectively harnessing a gravitational lens to boost the light grasp of the IRAM Plateau de Bure interferometer and the Spitzer telescopes by up to a factor of #30x, while also improving the effective resolution to 0.2". We detect strong CO(3-2) emission, allowing us to quantify the gas and dynamical mass of only the second LBG to be detected in molecular gas emission, while the Spitzer Space Telescope observations have allowed us to quantify the stellar mass and star-formation in the system. I will discuss what has been learned from this system as well as placing this LBG in context with other populations of local and high-redshift galaxies. These observations have provided a preview of the capabilities of ALMA, which will be able to routinely study "ordinary'' galaxies at high redshift.

Organic Chemistry of Southern Sources: Observations of Cha-MMS1 and IRAS 15194-5115 in ALMA bands 1 and 3

Martin Cordiner (NASA GSFC)

Steven B. Charnley (NASA Goddard Space Flight Center)

We present new spectra of molecule-rich sources in the southern hemisphere obtained using the ATNF Mopra telescope. Spectra and maps are presented of organic molecules detected between 30 and 50 GHz in the young Class 0 protostar Chamaeleon~MMS-1. The large abundances of polyynes, cyanopolyynes and methanol may be indicative of a warm carbon chemistry in the dense gas surrounding this protostar. Spectra are also presented from a 78-96 GHz scan of the carbon-rich AGB star IRAS~15194-5115, including new detections of HC5N, CCS and C13CH.

Hot Cores and Bipolar Molecular Outflows in GLIMPSE Extended Green Objects

Claudia Cyganowski (Harvard-Smithsonian CfA)

C. L. Brogan (NRAO)
T. R. Hunter (NRAO)
E. Churchwell (University of Wisconsin-Madison)
Q. Zhang (Harvard-Smithsonian Center for Astrophysics)

We present high angular resolution Submillimeter Array (SMA) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of two GLIMPSE Extended Green Objects (EGOs) - massive young stellar object (MYSO) outflow candidates identified based on their extended 4.5 micron emission in Spitzer images. The mm observations reveal bipolar molecular outflows, traced by high-velocity CO (2-1) and HCO+ (1-0) emission, coincident with the 4.5 micron lobes in both sources. SiO(2-1) emission confirms that the extended 4.5 micron emission traces active outflows. A single dominant outflow is identified in each EGO, with tentative evidence for multiple flows in one source (G11.92-0.61). The outflow driving sources are compact millimeter continuum cores, which exhibit hot-core spectral line emission and are associated with 6.7 GHz Class II CH3OH masers. G11.92-0.61 is associated with at least three compact cores: the outflow driving source, and two cores that are largely devoid of line emission. In contrast, G19.01-0.03 appears as a single MYSO. The difference in multiplicity, the comparative weakness of its hot core emission, and the dominance of its extended envelope of molecular gas all suggest that G19.01-0.03 may be in an earlier evolutionary stage than G11.92-0.61. Modeling of the G19.01-0.03 spectral energy distribution suggests that a central (proto)star (M ~ 10 Msol) has formed in the compact mm core (Mgas ~ 12 - 16 Msol), and that accretion is ongoing at a rate of ~10-3 Msol year-1. Our observations confirm that these EGOs are young MYSOs driving massive bipolar molecular outflows, and demonstrate that considerable chemical and evolutionary diversity are present within the EGO sample.

Red but not dead! Molecular gas in early-type galaxies

Timothy Davis (University of Oxford)

Katherine Alatalo (UC Berkeley)
Martin Bureau (University of Oxford)
Lisa Young (New Mexico Tech)
Leo Blitz (UC Berkeley)
The ATLAS#tex2html_wrap_inline493# team (various)

Over the past few years, early-type galaxies have shed their red and dead moniker, thanks to the discovery that many host low-level residual star formation. As part of the ATLAS3D project we are conducting a complete, volume limited survey of the molecular gas in 260 local early-type galaxies with the IRAM-30m telescope and the CARMA interferometer. With this data we are attempting to understand the origin of this molecular gas, and study its distribution, kinematics and star formation properties. We find that around 22% of early-type galaxies in the local volume host molecular gas reservoirs, with central discs, polar structures and rings being common. This detection rate is independent of galaxy luminosity and environment, but does depend on the galaxy kinematics. We find that although the molecular gas extent is smaller in early type galaxies, the linear size scales fairly robustly with the optical and stellar characteristic scale-lengths, independent of the galaxy morphology. The origin of the molecular gas seems to depend strongly on environment, with misaligned gas (indicative of externally acquired material) being common in the field but completely absent in Virgo. I will discuss the origin of the gas in these CO detected galaxies and touch on the implications for the formation and evolution of red sequence galaxies. I will also present kinematic analyses, including the first molecular gas Tully-Fisher relation for early-type galaxies, and show that molecules may be the kinematic tracer of choice for probing the M/L evolution of galaxies over cosmic-time.

Expanded spectral catalogs for ALMA: Strategies and Tools

Frank De Lucia (The Ohio State University)

Sarah M. Fortman (Ohio State University)
Ivan R. Medvedev (Wright State University)
Christopher F. Neese (Ohio State University)

There is a broad consensus that many, if not most, of the unidentified spectral lines in astrophysical spectra are due to transitions in highly perturbed excited vibrational states of a relatively small number of molecules, the astrophysical weeds. We have previously discussed a new experimental approach to address this problem. This approach does not require the time prohibitive assignment and quantum mechanical analysis of the traditional catalog method. However, the spectroscopic completeness of this approach results in a much larger database. These data can be transfer to the astrophysical community in a variety of ways, but because an order of magnitude larger number of lines is included, consideration must be given to implementation strategies. Strawman tools and evaluations of these tools will be presented. Feedback from the astrophysical community will be solicited.

The Origin and Evolution of the Galaxy Star Formation Rate Sequence

Aaron Dutton (University of Victoria)

Frank C. van den Bosch (Yale University)
Avishai Dekel (The Hebrew University)

We use a semi-analytic model for disk galaxies to explore the origin of the time evolution and small scatter of the galaxy SFR sequence --- the tight correlation between star-formation rate (SFR) and stellar mass (M*). The steep decline of SFR from z~2 to the present, at fixed M*, is a consequence of the following: First, disk galaxies are in a steady state with the SFR following the net (i.e., inflow minus outflow) gas accretion rate. The evolution of the SFR sequence is determined by evolution in the cosmological specific accretion rates, proportional to (1 + z)2.25, but is found to be independent of feedback. Although feedback determines the outflow rates, it shifts galaxies along the SFR sequence, leaving its zero point invariant. Second, the conversion of accretion rate to SFR is materialized through gas density, not gas mass. Although the model SFR is an increasing function of both gas mass fraction and gas density, only the gas densities are predicted to evolve significantly with redshift. Third, star formation is fueled by molecular gas. Since the molecular gas fraction increases monotonically with increasing gas density, the model predicts strong evolution in the molecular gas fractions, increasing by an order of magnitude from z=0 to z=2. On the other hand, the model predicts that the effective surface density of atomic gas is ~10 Msol pc-1, independent of redshift, stellar mass or feedback. Our model suggests that the scatter in the SFR sequence reflects variations in the gas accretion history, and thus is insensitive to stellar mass, redshift or feedback. The large scatter in halo spin contributes negligibly, because it scatters galaxies along the SFR sequence.

Initial highlights of Herschel Gould Belt Survey observations of Cepheus

Cassandra Fallscheer (NRC-HIA)

James Di Francesco (NRC-HIA)
Peter Martin (CITA)
Christine Wilson (McMaster University)
Sarah Sadavoy (University of Victoria)
Philippe André (CEA Saclay)

The Herschel Space Telescope has been obtaining astonishing far-infrared/submillimeter data since its launch in May 2009. We are working with 70, 160, 250, 350, and 500 micron data taken in parallel mode with the PACS and SPIRE instruments of five clouds in the Cepheus star formation region: L1157, L1172, L1228, L1241, and L1251. These data are part of the larger Key Project, the Herschel Gould Belt Survey (PI: Ph. André) and are rich with filamentary structures, protostars, and bubbles. With these data, we will characterize both the compact sources as well as the non-compact structures associated with each cloud. By overlaying SPITZER data, it will be possible to identify pre- and protostellar cores and deduce respective core mass functions. The Cepheus region is a typical member of the Herschel Gould Belt Survey which as a whole will include many other excellent targets for future observations with ALMA and other interferometers.

A rotating circumstellar disk around a high-mass protostar in IRAS 18162-2048

Manuel Fernandez (Instituto de Astronomia, UNAM)

Curiel, S. (IA, UNAM, Mexico)
Girart, J.M. (Institut de Ciencies de l'Espai, CSIC-IEEC, Spain)
Ho, P.T.P. (Academia Sinica Institute for Astronomy and Astrophysics, Taiwan)
Nimesh, P. (Harvard-Smithsonian Center fof Astrophysics, USA)
Gomez, Y. (CRyA, UNAM, Mexico)

We have carried out sub-arcsecond SMA observations towards the central region of the HH~80--81 system. The mm continuum emission shows two main sources, one of them located at the center of the extremely large (5.3~pc long) bipolar radio continuum jet observed in this region. The dust emission appears compact and coincides with a radio continuum source. Between the spectral lines detected, the SO2 line transitions show compact emission towards this source. These molecular lines clearly show a velocity gradient perpendicular to the radio jet axis. Both, the dust continuum and the molecular line emission suggest the existence of a rotating circumstellar disk around a massive protostar.

Imaging the cold neutral medium in high redshift HI rich galaxies

Michele Fumagalli (University California, Santa Cruz)

J. Xavier Prochaska (University California, Santa Cruz)
Arthur M. Wolfe (University of California, San Diego)

The [C II] fine-structure transition is the most luminous line emitted by the Galaxy interstellar medium and it is the principal coolant of its cold neutral medium (CNM). At high redshift, a significant fraction of HI rich galaxies that are detected as damped Lyman alpha systems (DLAs) contains CNM gas and shows CII* lambda1335.7 absorption. This transition originates from the same excited state that gives rise to the [C II] 158μm line and it is natural to expect that these DLAs are sources of 158μm radiation. We study whether DLAs that show strong CII* absorption can be detected with ALMA at z = 2 by using high resolution hydrodynamical simulations of galaxies. Our model includes radiative transfer of ionizing radiation and a subgrid prescription to compute the molecular fraction and [C II] emissivity in the CNM. Our preliminary results are encouraging as galaxies with halo masses M > 1011Msol have integrated fluxes between 4mJy − 0.8mJy,, depending on the star formation rate. The ability of ALMA to detect the [C II] line at z = 2 will open a completely new path to study the cold gas and star formation in the high redshift universe. For the first time, interferometer maps will reveal the sizes of HI selected galaxies, currently unknown. By combining the sizes with the 158μm velocity widths, masses can be derived and, relating the 158μm luminosity to the gas heating rate, star formation rates can be measured.

Dense molecular gas tracers and star formation rate in galaxies

Yu Gao (Purple Mountain Observatory, CAS)

High-dipole moment molecules such as HCN and CS trace much denser molecular gas than that of CO, which traces the total molecular gas mass. HCN strongly and linearly correlates with the far-infrared (FIR) emission for essential all star-forming systems near and far. CS observations in galaxies further demonstrate similarly tight correlations. Such tight linear FIR - dense molecular gas correlation suggests that the star formation rate depends linearly upon the mass of dense molecular gas and the dense cores might be the basic units of massive star formation in galaxies. The order-of-magnitude increases in both the spatial resolution and sensitivity of the ALMA will reveal many such dense cores in local galaxies and revolutionize our understanding of the formation of massive stars in galaxies.

Evolution of the molecular gas fraction and predictions for ALMA redshift surveys

James Geach (McGill)

Carlton Baugh (Durham)
Cedric Lacey (Durham)
Ian Smail (Durham)
Claudia Lagos (Durham)
Alex Merson (Durham)

Tracking the evolution of the molecular gas fraction of galaxies across cosmic time is a powerful observational probe into the evolution of galaxies, as the gas fraction encodes information about the relative depletion/accretion of cold gas in galaxies. I present new IRAM PdBI observations of stellar mass dominated star-forming galaxies at z = 0.4 which can be placed in context with recent observations of high-z molecular gas dominated discs (z ~ 1-2), and local systems to show the evolution of the molecular gas content of normal star-forming galaxies over ~8 Gyr of cosmic history. The observed evolution is well modelled by the latest semi-analytic models of galaxy formation, which include realistic prescriptions for the mass of molecular gas in galaxies within the lambdaCDM framework. We have been constructing mock ALMA lightcones from these simulations, with a semi-empirical method of assigning molecular and far-IR cooling line emission from galaxies. These can be used to perform mock ALMA simulations such as blind redshift surveys. I will present some of our findings, and discuss implications for planning deep cosmological surveys with ALMA.

SMA spectropolarimetric observations of IRC+10216: Is molecular line emission polarized?

Josep Miquel Girart (Institut de Ciencies de l Espai (CSIC-IEEC))

Nimesh Patel ((Submillimeter Array))
Ramprasad Rao (Institute of Astronomy and Astrophysics, Academia Sinica)
Wouter Vlemmings, (Argelander-Institut für Astronomie)

We present spectropolarimetric observations of IRC+10216 (CW Leo), a well known archetype of an asymptotic giant branch (AGB) carbon star. This star is located at a distance of 150 pc and presents a high mass-loss rate (several 10-5 Msol yr-1). There are nearly 60 molecules observed in the circumstellar shell of IRC+10216. The observations we performed at 345 GHz using the recently increased bandwidth, 4GHz per side band. This allowed us to observe simultaneously strong molecular line emission such as CS 7-6, CO 3-2, SiS 19-18, H13CN 4-3. The lines of these species are predicted to be linearly polarized due to the strong IR radiation and the presence of a magnetic field (Goldreich Kylafis 1982; Deguchi Watson 1984; Morris, Lucas Omont 1985). In this poster we will present the results for the aforementioned lines.

Molecular Gas in Lyman Break Analogs

Thiago Gonçalves (Caltech)

Lyman Break Analogs (LBAs) are a population of star-forming galaxies at low redshift (z~0.2). These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating their detailed study as potential local analogs to high-redshift starburst galaxies. In a recent paper we presented results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We have initiated a program with the CARMA array to detect molecular gas in these galaxies, in an attempt to characterize the physical properties of the gas reservoir available for star formation and the implications for galaxy formation models. Preliminary results show that LBAs present similar gas fractions as those observed in high-redshift starburst galaxies. This work will serve as a pilot study for ALMA; once the new array becomes available, we will be able to measure gas surface densities at scales of tens of parsecs, and for the first time determine the spatially resolved Schmidt-Kennicutt law for starbursts at cosmic distances.

SiO J=7-6 and J=8-7 masers in AGB stars

Malcolm Gray (University of Manchester)

The J=7-6 and J=8-7 transitions of SiO are found in ALMA band 7. Most previous observations have been possible only with single-dish instruments, and have shown that masers in these transitions are generally weaker and less consistent than the better known lines at 43 and 86GHz. The J=7-6 and J=8-7 masers often disappear for a significant fraction of the stellar period. ALMA will be able to produce maps of the maser region in these lines for comparison with computer models and with lower frequency observations. The high frequency lines may hold the key to understanding of the maser pumping scheme, because they are the highest inverted transitions in each excited vibrational state.

Nearby galaxies seen through the SpIOMM imaging Fourier transform spectrograph

Jonathan Heiner (Université Laval)

Anne-Pier Bernier (Université Laval)
Laurie Rousseau-Nepton (Université Laval)

The SpIOMM instrument at the Mont Megantic observatory offers a unique capability in the optical wavelength range: it provides a 12 arcminute circular field of view image while at the same time providing full spectra of each pixel at a low to moderate spectral resolution. I will briefly present the history and capabilities of this instrument, and provide an overview of recent observations and results. In particular, I will focus on observations of nearby galaxies, where SpIOMM can provide a sample of spatially resolved HII regions across galactic disks limited only by sensitivity constraints. Among others, this provides an opportunity to measure metallicities going beyond radial trends and study true spatial variations. We have observed galaxies such as M33, M101 and NGC 2403. Finally, I will highlight the capabilities of SpIOMM's successor, SITELLE, that is being built for the Canada-France-Hawaii telescope.

Searching for CO(1-0) at very high redshift

Ian Heywood (University of Oxford)

The J=1-0 transition for 12CO is the best tracer of molecular gas in galaxies. Primarily studied at mm and sub-mm wavelengths (nurest = 115.27 GHz) the line enters the higher frequency bands of cm-wave interferometers at very high (~7) redshift.

Observing at such wavelengths offers a field-of-view advantage, which together with the broadband correlators and high-sensitivity of current and future instruments opens up for the first time the prospect of conducting systematic searches for molecular line emission within significant cosmological volumes during the Epoch of Reionization.

In this talk I will present some of the challenges inherent in such observations, and asses their feasibility using our existing semi-analytic galaxy simulation together with a CASA-based instrumental simulation pipeline.

Many optical and near-IR campaigns are in progress which are dedicated to the search for galaxies at z > 7, and cross-correlation of such line catalogues with the datacubes obtained from radio interferometers will be very valuable. I will present a new layer for our sky simulation which predicts the yield of arbitrary Lyman-alpha line surveys, and demonstrate the viability of obtaining stacked CO line detections from sources which are undetected in the simulated radio data. Pilot observations in order to perform such a study have been applied for using the EVLA and VISTA telescopes.

Finally I will also introduce our Large Survey project for the South African SKA pathfinder MeerKAT, which in the recent proposal review was awarded 6500 hours to conduct a search for CO(1-0) at z~7--10.

The many objects we expect to discover in both the radio and narrowband observations will be ideal targets for ALMA, which will be necessary to obtain high spatial resolution, high fidelity imaging, and to constrain the gas physics via its ability to observe higher-#tex2html_wrap_inline593# CO lines and other diagnostic lines such as [CII].

Primary Beam Shape Calibration from Mosaicked, Interferometric Observations

Chat Hull (UC Berkeley)

Geoffrey C. Bower (UC Berkeley)
Steve Croft (UC Berkeley)
Peter K. G. Williams (UC Berkeley)
Casey Law (UC Berkeley)
David Whysong (UC Berkeley)

Image quality in mosaicked observations from interferometric radio telescopes is strongly dependent on the accuracy with which the antenna primary beam is calibrated. The next generation of radio telescope arrays such as the Allen Telescope Array (ATA) and the Square Kilometer Array (SKA) have key science goals that involve making large mosaicked observations filled with bright point sources. We present a new method for calibrating the shape of the telescope's mean primary beam that uses the multiple redundant observations of these bright sources in the mosaic. The method has an analytical solution for simple Gaussian beam shapes but can also be applied to more complex beam shapes through chi-square minimization. One major benefit of this simple, conceptually clean method is that it makes use of the science data for calibration purposes, thus saving telescope time and improving accuracy through simultaneous calibration and observation. We apply the method both to 1.43 GHz data taken during the ATA Twenty Centimeter Survey (ATATS) and to 3.14 GHz data taken during the ATA's Pi Gigahertz Sky Survey (PiGSS). We find that the beam's calculated full width at half maximum (FWHM) values are consistent with the theoretical values, the values measured by several independent methods, and the values from the simulation we use to demonstrate the effectiveness of our method on data from future telescopes such as the expanded ATA and the SKA. These results are preliminary, and can be expanded upon by fitting more complex beam shapes. We also investigate, by way of a simulation, the dependence of the accuracy of the telescope's FWHM on antenna number. We find that the uncertainty returned by our fitting method is inversely proportional to the number of antennas in the array.

Imaging the chemical segregation in massive hot cores with the SMA: The case of AFGL2591

Izaskun Jimenez-Serra (Harvard-Smithsonian Center for Astrophysics)

Qizhou Zhang (Harvard-Smithsonian Center for Astrophysics)
Jesus Martin-Pintado (Centro de Astrobiologia (CSIC/INTA))
Serena Viti (University College London )
Willem-Jan de Wit (European Southern Observatory)

Hot cores are hot, compact and dense condensations that represent one of the earliest stages in the massive star formation process. These objects are chemically very rich and are predicted to show a chemical segregation naturally produced by the progressive decrease of the gas and dust temperature with increasing distance to the central star. Since this segregation is expected to occur at spatial scales of <~1300 AU (i.e. at scales of <~1" at the typical distances of massive star forming regions), its detection has remained elusive. Here, we present very high angular resolution observations (beam of 0.3", 300AU) recently carried out with the SMA toward the massive hot core in the AFGL2591 star forming region. Thanks to the total 8GHz bandwidth available at the SMA, we have simultaneously imaged the emission of key molecular species such as CH3OH, H2CO, H2S, SO, SO2, OCS or HC3N with unprecedented high-angular resolution. The SMA images show a very clear chemical segregation of the molecular gas within the hot core around AFGL2591, with i) H2S distributed in an inner and hotter core; ii) SO2, HC3N , and OCS peaking at an outer and cooler envelope; and iii) CH3OH distributed in an external shell that surrounds the previous two molecular envelopes. By comparing our SMA results with (gas phase+dust grain) chemical modelling, we constrain the physical properties of the different shells/envelopes within the AFGL2591 hot core, and conclude that the observed chemical segregation is a direct consequence of two different chemical processes: a strong UV photodissociation and a high-temperature gas-phase chemistry. This pilot study shows the need to carry out comprehensive studies of the chemical complexity in massive hot cores at very high angular resolutions, in order to clearly establish their physical structure within spatial scales of 1300 AU. With its large simultaneous bandwidth and very high-angular resolution, ALMA constitutes a key instrument that will help to unveil the physical processes involved in the formation of massive stars.

Gas-rich Detections in Nearby Clusters

Brian Kent (NRAO)

A sample of gas-rich detections from the Virgo Cluster are presented. In addition to many HI deficient late-type galaxies that inhabit the periphery of the cluster, detections of low-mass tidal debris clouds throughout the cluster have been made near the survey mass limit at the Virgo distance (log(MHI)=7.3). The HI content of the galaxies in the cluster, the HI mass function for the sample of member galaxies, and various physical properties as a function of galaxy morphology will be discussed. A number of low HI-mass clouds are seen toward the western M region of Virgo, where the galaxy population is thought to lie behind the main A cluster surrounding M87. Aperture synthesis observations of two HI cloud complexes have resolved the HI detections made with Arecibo. The HI detections cannot be identified with any optical, IR, or UV emission from available archival imaging. One of these detections appears to be the most isolated optically inert object observed in the outer reaches of Virgo (Kent 2010).

Gas Dynamics in Massive Star Forming Regions

Pamela Klaassen (ESO)

Christine Wilson (McMaster University)
Eric Keto (CfA)
Qizhou Zhang (CfA)

Massive stars play a large role in the evolution of galaxies; from injecting turbulence into the ISM, to enriching their environments with heavy elements. Yet, it is still unclear how they form. Because of their distance, and the fact that they are very embedded, we are often limited to studying the surroundings of young massive stars in order to better understand their formation. To this end, I observed a number of high mass star forming regions at high angular resolution (#tex2html_wrap_inline623#) through a combination of observations obtained at the SMA and JCMT. From these observations, I find that the warm molecular gas surrounding each HII region is undergoing bulk rotation, and that infall, when detected, is occurring preferentially along the rotation direction. Perpendicular to this, I find evidence for large scale outflows being powered by a source within the HII region itself. I present a quantitative kinematic analysis of these bulk motions and compare them with the kinematic properties of the ionized gas in the same regions to provide a coherent picture of the total gas dynamics in massive star forming regions.

Interstellar Pyrimidine

Yi-Jehng Kuan (National Taiwan Normal University)

Yo-Ling Chuan (National Taiwan Normal University)
Chi-Hung Yan (National Taiwan Normal University)
Yusen Hsu (National Taiwan Normal University)

Wealthy complex organic molecules which may also be prebiotically important and fundamental to large organic macromolecules are known to exist in hot molecular cores of massive star-forming regions. A key interstellar molecule for astrobiology would be pyrimidine (c-C4H4N2), the unsubstituted ring analogue for three of the DNA and RNA bases: thymine, cytosine and uracil. We have therefore searched for the nucleic acid building-block pyrimidine in Orion KL, which is known to contain the molecular precursors of this heterocyclic ring molecule, using the Submillimeter Array. The preliminary positive results of SMA are rather encouraging though not conclusive. Further observations with higher sensitivity are thus needed for a definite detection of interstellar pyrimidine.

Methanol photodissociation and its effect on complex chemistry in the interstellar medium

Jacob Laas (Emory University)

Jacob C Laas (Department of Chemistry, Emory University, Atlanta, GA 30322)
Robin T Garrod (Department of Astronomy, Cornell University, Ithaca, NY 14853)
Eric Herbst (Departments of Physics, Chemistry and Astronomy, The Ohio State University, Columbus, OH 43210)
Susanna L Widicus Weaver (Department of Chemistry, Emory University, Atlanta, GA 30322)

A variety of complex organic molecules have been detected in the interstellar medium, but the chemical pathways to these molecules are not well-understood. Grain surface chemistry plays an important role in their formation, where radical-radical combination reactions on ice surfaces can efficiently form these molecules during star formation. One major source of radicals that ultimately react to form complex organics is thought to be methanol photodissociation. However, the branching ratios for this process are not well-characterized. To this end, we are conducting laboratory measurements of methanol photodissociation via quantitative terahertz (THz) spectroscopy. We are also using chemical modeling to test the effects of these branching ratios on the formation of complex organics in interstellar environments. Here we present the initial results of the laboratory and modeling work and discuss the implications of these results for interstellar complex organic chemistry.

New Tool For Astrochemstry: 18 to 26 GHz Focal Plane Array

Glen Langston (NRAO - GB)

Steve White (NRAO)
Bob Garwood (NRAO)
Joe Masters (NRAO)
Amy Shelton (NRAO)

Astronomers using the Green Bank Telescope's 18-26 GHz Focal Plane Array (FPA) receiver have successfully imaged regions exhibiting a variety of molecular emission lines. These FPA observations and data reduction pipeline tools were used to measure the density and temperature of these star forming regions.

We present the capabilities and measured performance of the FPA. We focus our presentation on observations of the massive star forming region W51, with rivals Orion in the complexity of emission. During commissioning observations, we measured the distribution of Ammonia emission transitions from (1,1) through (6,6). The system shows good performance over this wide frequency range.

This presentation highlights great new capabilities of FPAs for astro-chemistry and potential for new research applications.

A High Resolution NIR Spectroscopic Survey of FUors and EXors

Joseph Liskowsky (Clemson University)

Sean Brittain (Clemson University)
Terrence Rettig (University of Notre Dame)
Erika Gibb (University of Missouri St. Louis)
Theodore Simon (University of Hawaii)

As part of an ongoing effort to monitor and classify the small group of known young eruptive variables, we present High Resolution NIR (2-5 micron) spectra of 4 FUor, EXor and FUor-Like sources which show emission and absorption features not necessarily indicative of their presumed classification. This work makes clear that the natures of these objects are not well described by singular classic FUor or EXor accretion models and begins to define a continuum of source types. Specifically, ZCMa, an FUor-like system, as well as PV Cep, an EXor system, show CO absorption at 5 microns but exhibit CO emission at 2 microns, while Brackett gamma is also in emission for both. XZ Tau, a purported EXor, shows Brackett gamma is in emission while the CO at both 2 and 5 microns is in absorption. L1551 IRS 5 shows absorption for CO at 2 microns, but shows emission at 5 microns. Weak Brackett gamma absorption is detected for this source. We discuss the implications of using the overtone bandheads as a circumstellar diagnostic.

Discovery of an expanding molecular bubble in Orion BN/KL

Laurent Loinard (Centro de Radioastronomia y Astrofisica - UNAM)

Luis A. Zapata (CRyA-UNAM)
Luis F. Rodriguez (CRyA-UNAM)
JohannesSchmid-Burgk (MPIfR)
Paul Ho (ASIAA CfA)
Nimesh A. Patel (CfA)

During their infancy, stars are well known to expel matter violently in the form of well-defined, collimated outflows. A fairly unique exception is found in the Orion BN/KL star-forming region where a poorly collimated and somewhat disordered outflow composed of numerous elongated "finger-like'' structures was discovered more than 30 years ago. In this talk, we report the discovery in the same region of an even more atypical outflow phenomenon. Using 13CO(2-1) line observations made with the Submillimeter Array (SMA), we have identified there a 500 to 1,000 years old, expanding, roughly spherically symmetric bubble whose characteristics are entirely different from those of known outflows associated with young stellar objects. The center of the bubble coincides with the initial position of a now defunct massive multiple stellar system suspected to have disintegrated 500 years ago, and with the center of symmetry of the system of molecular fingers surrounding the Kleinmann-Low nebula. We hypothesize that the bubble is made up of gas and dust that used to be part of the circumstellar material associated with the decayed multiple system. The Orion hot core, recently proposed to be the result of the impact of a shock wave onto a massive dense core, is located toward the south-east quadrant of the bubble. The supersonic expansion of the bubble, and/or the impact of some low-velocity filaments provide a natural explanation for its origin.

Follow-up of lensed submillimeter galaxies with Z-Spec and ALMA

Roxana Lupu (University of Pennsylvania )

Z-Spec team
H-ATLAS consortium
SPT collaboration
HerMES collaboration

Recent theoretical and observational studies show that most of the extremely bright submillimeter galaxies (SMGs) at wavelengths larger than 500 μm are lensed by foreground objects. Large area surveys, such as the Herschel H-ATLAS, HerMES, and the South Pole Telescope (SPT) survey, uncover a large number of such sources. This makes it possible for ground based instruments to obtain data on typical star forming galaxies at high redshifts that would otherwise be inaccessible. Our instrument Z-Spec, a grating spectrograph with simultaneous coverage over the 190-308 GHz bandpass, can detect multiple CO lines for redshifts greater than ~0.6. Z-Spec has proven to be an efficient redshift machine, measuring 12CO redshifts for some of the brightest sources found in the large area surveys, circumventing the need for optical or radio counterpart identification. However, the derivation of the physical properties of the gas (density, temperature, CO abundance) from Z-Spec data alone is limited by the unknown source size and the small number of CO lines measured. With ALMA, we can resolve the source morphology and the line profiles, and derive the source sizes, lensing magnification factors, bulk motions of the gas, and constrain the dynamical masses. In addition, the precise redshift determination from Z-Spec together with the large sensitivity of ALMA will allow us to measure fainter lines from high density tracers, such as HCN, HNC, HCO+, and 13CO, as well as to look for a number of excited water lines. In combination with other multi-wavelength follow-ups, these data will enable a detailed study of the processes governing dust-obscured star forming galaxies at high redshifts.

A Submillimeter Array Survey of Disk Masses in Orion

Rita Mann (NRC/HIA)

Jonathan Williams (University of Hawaii, IfA)

The formation of planetary systems is intimately connected to the properties of the circumstellar disks in which they are born. Disk studies to date have focused on low mass star forming regions like Taurus and rho Ophiuchus for their proximity, however, stars rarely form in such quiescent environments. Most stars, including our Sun, form in rich clusters near massive O-type stars. I will present the results of our Submillimeter Array (SMA) survey at 850 microns, which was conducted to determine the distribution of disk masses in Orion, the nearest young, massive star forming region to the Sun. This study has enabled us to assess the influence massive stars have on potential planet formation around nearby lower mass stars.

The most massive galaxies at 3<z<4: star-bursting or hosting active galactic nuclei?

Danilo Marchesini (Tufts University)

We use the optical to mid-infrared coverage of the NEWFIRM Medium-Band Survey (NMBS) to characterize, for the first time, the properties of a mass-complete sample of 14 galaxies at 3<z<4 with stellar masses larger than 2.5x1011 Msol, and to derive significantly more accurate measurements of the high-mass end of the stellar mass function (SMF) of galaxies at 3<z<4. The typical very massive galaxy at z=3.5 is red and faint in the observer's optical. About 60% of the mass-complete sample have optical colors satisfying either the U- or the B-dropout color criteria, although ~50% of these galaxies have R>25.5. About 30% of the sample has SFRs from SED modeling consistent with zero. However, >80% of the sample is detected at 24 μm, resulting in total infrared luminosities in the range (0.5-4.0)x1013 Lsol, typical of ultra- and hyper-luminous infrared galaxies. This implies the presence of either dust-enshrouded starburst activity (with SFRs of 600-4300 Msol yr-1) and/or highly-obscured active galactic nuclei (AGN). The previously found disagreement at the high-mass end between observed and model-predicted SMFs is now significant at the 3 sigma level when only random uncertainties are considered. However, systematic uncertainties dominate the total error budget, bringing the observed SMF in marginal agreement with the predicted SMF. Additional systematic uncertainties on the high-mass end could be potentially introduced by either 1) the intense star-formation and/or the very common AGN activities as inferred from the MIPS 24μm detections, and/or 2) contamination by a significant population of massive, old, and dusty galaxies at z~2.6.

Dissecting the ISM in the nuclei of galaxies through chemistry

Sergio Martin (European Southern Observatory)

The chemical composition of the ISM in the central region of galaxies can be a powerful tool to study these obscured environments. For instance, the spectral line survey towards the ULIRG Arp~220 has revealed an impressive molecular richness similar to that in Galactic hot cores. I will discuss which would be the key tracers detected in this galaxy and how they reveal the source powering its bright IR emission.

However, in order to understand the chemistry in the nuclei of galaxies, the Galactic Center region within our own Galaxy provide the perfect local laboratory. In particular the Circumnuclear Disk (CND) around the central black hole (Sgr A*) is likely the most extreme environment for the molecular gas. I will describe the chemical studies in this region and will present the molecular line survey recently carried out with the SMA. This survey will provide key information as a test bed for molecular studies and for comparison with other galaxies.

Design and Construction of a High-Resolution Terahertz Cavity Ringdown Spectrometer

Brett McGuire (Emory University)

Brandon Carroll (Emory University)
Susanna Widicus Weaver (Emory University)

Cavity Ringdown Spectroscopy (CRDS) is an extremely sensitive high-resolution spectroscopic technique typically utilized in the visible and IR spectral windows. Given its sensitivity, cavity ringdown is a useful technique for the detection and characterization of unstable or trace species. High-resolution data for astrochemically-relevant molecules in the terahertz (THz) frequency range are necessary to interpret observational spectra. This is especially crucial in the current era of astronomical observations, where the science mission of the Herschel Space Observatory is well-underway, the first science flights for the Stratospheric Observatory for Infrared Astronomy (SOFIA) are being conducted, and the science commissioning for the Atacama Large Millimeter Array (ALMA) is forthcoming, There are currently no high-resolution techniques with sufficient sensitivity in the frequency ranges of these observatories to enable characterization of most unstable molecules. Therefore, we have constructed a benchtop THz-CRDS system using two wire-grid polarizers to form the high-reflectivity cavity. We are working to acquire a ringdown signal from the system before integrating it into a vacuum chamber for spectroscopic studies. We plan to use this spectrometer to acquire spectra of trace and unstable species of astrochemical interest across the THz spectral window. We will report on this instrument development and our plans to produce and investigate reactive or unstable organic molecules thought to be key intermediates in interstellar organic reactions.

Integral Field Spectroscopy with Adaptive Optics of Halpha emission in z~2 Submm Galaxies

Karin Menendez-Delmestre (Carnegie Observatories)

Andrew W. Blain (Caltech)
Mark Swinbank ( Institute for Computational Cosmology, Durham University, Durham DH1 3LE, UK)
Ian Smail ( Institute for Computational Cosmology, Durham University, Durham DH1 3LE, UK)
Rob J. Ivison ( UK Astronomy Technology Centre, Blackford Hill, Edinburgh EH9 3HJ; Institute for Astronomy, Blackford Hill, Edinburgh EH9 3HJ)
Scott C. Chapman ( Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, U.K)

Ultra-luminous infrared galaxies are locally rare, but dominate the co-moving energy density at higher redshifts (z>2). Many of these are dust-obscured galaxies that have been identified by the detection of their thermal dust emission at sub-mm wavelengths. We present the first integral-field spectroscopic observations aided by Laser Guide Star Adaptive Optics on a handful of z~2 submillimeter galaxies (SMGs) taken with the OSIRIS instrument on Keck. The spatially-resolved, 2D spectroscopic insight that AO-aided integral field observations provide is the only viable probe of the spatial distribution and line-of-sight motion of ionized gas within these galaxies. By tracing the regions undergoing star formation, the distribution of (narrow-line) Halpha emission can also provide us with a mapping of the star-forming molecular and presumably gas-rich regions that fuel this activity. Even though CO observations have a direct view of the distribution of molecular gas throughout a galaxy, the ionized gas surrounding massive stars is expected to mix with the molecular gas medium, thus giving an additional window to characterize the molecular gas budget of a galaxy.

I will discuss various aspects of SMGs in the light of these observations, including: the spatial distinction of AGN and star-forming regions as revealed by differences in H-alpha spectral properties; their merger-like kinematics suggested by velocity offsets between individual galactic-scale sub-components; their high SFR surface densities similar to local extremes like ULIRGs and circumnuclear starbursts; and their large spatial extensions, which suggest that SMGs may be undergoing such intense star-forming activity on scales of ~8-16 kpc, in sharp contrast to local ULIRGs and other extreme local compact environments. I will present these results against the backdrop of past and recent high-resolution CO observations on these galaxies and in the light of future ALMA observations.

The chemical structure of W49A - a single dish study in preparation for ALMA

Zsofia Nagy (Kapteyn Astronomical Institute)

Floris van der Tak (SRON Netherlands Institute for Space Research)
Gary Fuller (Jodrell Bank Centre for Astrophysics, University of Manchester)
Rene Plume (Department of Physics and Astronomy, University of Calgary)
Marco Spaans (Kapteyn Astronomical Institute)

With a luminosity of LIR>107 Lsol and a mass of M>107 Msol, W49A is the most active star-forming region in the Galactic disk. By providing similar physical conditions to starbursts galaxies, it can be used as a Galactic starburst analogue. The explanation for the high star-formation activity of the region is still an open question.

We present results based on the JCMT Spectral Legacy Survey (SLS). The SLS observed a 2'x2' field with 15'' angular resolution around the center of W49A in the frequency range between 330 and 373 GHz. We have selected a sample of molecular lines to probe the physical properties (such as kinetic temperatures, rotational temperatures and column densities) of W49A. By comparing spatial distributions of the integrated line intensities, we trace the chemical structure of the cloud. We investigate the analysis of the kinematics of the source by studying the line profiles. We report the detection of infall signatures toward the source center and the 'eastern tail' in HCN and HNC.

ALMA with its high angular resolution might be able to answer the question of the high star formation activity of the source. It will be able to resolve individual objects and provide parameters for high-mass protostars.

Formation of Keplerian Disks around Protostars

Nagayoshi Ohashi (ASIAA)

It is well known that Keplerian disks are formed around young stars in the course of star formation. In fact, several Keplerian disks, which are also often called protoplanetary disks, have been found around pre-main-sequence stars. It is naturally considered that these Keplerian disks around pre-main-sequence stars are formed in the prostellar phase. It has been, however, difficult for us to unambiguously identify such Keplerian disks forming around protostars. The reasons are that Keplerian disks forming around protostars are compact and also surrounded optically think infalling envelopes. In order for us to unambiguously identify Keplerian disks around protostars, it is necessary for us to observe both Keplerian disks and infalling envelopes at a high angular resolution, and to derive rotation curves of disks precisely. We have been using the Submillimeter Array (SMA) to identify Keplerian disks forming around protostars, and obtain a couple of cases showing strong hints of the disk formation around protostars. In this talk, I will present results obtained with SMA to discuss possible disk formation around protostars. I will also discuss how ALMA can help to unambiguously identify Keplerian disks around protostars.

SMA Spectral-line Surveys of Evolved Stars

Nimesh Patel (Harvard-Smithsonian Center for Astrophysics)

Ken Young (Harvard-Smithsonian Center for Astrophysics)
Karl Menten (Max Planck Institute for Radio Astronomy)
Carl Gottlieb (Harvard-Smithsonian Center for Astrophysics)

We report results from spectral-line surveys of three evolved stars, the extreme carbon star IRC+10216, oxygen rich supergiant VY CMa, and oxygen rich AGB star IK Tau, carried out with the Submillimeter Array (SMA). The frequency range was 279.0 to 355.0 GHz for VY CMa and IK Tau, and 293.9 to 354.8 GHz for IRC+10216. Maps at an angular resolution of ~3" were obtained for each line. VY CMa and IK Tau were observed with the SMA in extended configuration and angular resolution of ~1". These maps are useful for comparison of abundances in the circumstellar shell with chemical models, as well as provide constraints on physical conditions of excitation, which may help in identification of some of the unassigned lines. The spectrum of IRC+10216 is the richest, with a total of 442 lines, of which more than 200 are detected for the first time. A substantial new population of narrow lines with an expansion velocity of ~4 km/s (i.e. ~30% of the terminal velocity) was detected. Most of these are attributed to rotational transitions within vibrationally excited states, emitted from energy levels above the v=0, J=0 ground state with excitation energy of 1000--3000~K. The line survey data on IRC+10216 are released publicly as calibrated visibilites and imaged data cubes.

Herschel Spectroscopic Lessons for ALMA

John Pearson (Jet Propulsion Laboratory, California Institute of Technology)

Spectroscopy with Herschel provides a unique opportunity to determine what might be expected from ALMA. Herschel’s Heterodyne Instrument for Far Infrared (HIFI) has a specifically designed line survey mode, which allows for comprehensive spectroscopy, providing enormous insight into what is present in the gas phase. HIFI data coupled with ground based interferometer observations quickly show that the typical rich molecular source size is much smaller than the beam of the 3.5 meter Herschel telescope. As such, the observed HIFI spectra is usually a convolution of several sources within the beam. Regardless, HIFI has shown rich line sources to be very bright to well over 1 THz or the entire ALMA band. ALMA will fully resolve many sources even in its most compact configuration so that the only dilution will be the aperture filling factor. The HIFI observations, estimated source sizes and ALMA sensitivities allow for calculation of what to expect in ALMA data. In the absence of line confusion, ALMA can be expected to produce spectra with similar dynamic range to the best available laboratory spectra. These expectations are compared to available molecular data for Methanol and Ethyl Cyanide to provide an example of what will be required from catalogs, laboratory astrophysicist and astrophysical spectroscopists in the ALMA era.

Molecular Tracers of Turbulent Shocks in Giant Molecular Clouds

Andy Pon (University of Victoria)

Doug Johnstone (NRC-HIA)
Michael J. Kaufman (San Jose State University)

We are investigating the manner in which energy flows through, into, and out of molecular clouds in order to better understand how energy is conserved throughout a cloud's lifetime. In particular, we examine the dissipation of turbulent energy through shocks. Current numerical simulations show that the turbulent energy of a GMC dissipates on the order of a crossing time, but do not explicitly follow how this energy is released. We run models of C-type shocks, based on Kaufman Neufeld (1996), propagating into gas with a density of 1000 cm-3 at velocities of a few km/s, appropriate for the ambient conditions inside of a GMC, to determine which species and transitions dominate the cooling and radiative energy release associated with shock cooling of turbulent molecular clouds. Combining these models of shock emission and estimates for the rate of turbulent energy dissipation (Basu Murali 2001), based upon the conditions in nearby molecular clouds, we predict those line emissions that will be observable with current and upcoming observational facilities such as Herschel, SOFIA and ALMA. We also compare the turbulent energy dissipation rate to the cosmic ray heating rate and the ambipolar diffusion heating rate.
Basu, S. Murali, C. 2001, ApJ, 551,743
Kaufman, M. J. Neufeld, D. A. 1996, ApJ, 456, 250

New Frontiers in Intermediate-Mass Star Formation for ALMA

Matthew Povich (The Pennsylvania State University)

Intermediate-mass young stellar objects (YSOs) have masses in the range 2--8 Msol and form an important transitional class of objects, including Herbig Ae/Be stars and their less-evolved progenitors, spanning the gap between low-mass pre-main-sequence (T Tauri) stars and young massive stars that dominate Galactic and extragalactic H~II~regions. I will present recent results from the Spitzer Space Telescope that reveal large populations of intermediate-mass YSOs distributed throughout giant molecular clouds associated with the M17 and Carina giant H~II~regions, both of which are in the southern Galactic plane and accessible to ALMA: (1) The circumstellar disk lifetime for intermediate-mass YSOs appears to decrease rapidly as a function of increasing stellar mass, but the precise relationship is poorly constrained, and the primary physical mechanism responsible for disk destruction is unknown. (2) The mass function of extremely young stellar populations appears to be significantly ``bottom-heavy.'' Does this indicate that low- and intermediate-mass stars begin forming first, before the onset of massive star formation via a different process? (3) In H II regions like the Carina Nebula that are dominated by stellar winds and radiation from OB stars, the current star formation rate remains high. Is this ongoing star formation triggered or regulated by massive star feedback? There are myriad opportunities for ALMA to provide substantial advancement beyond these frontiers, including: (1) Measure circumstellar disk masses and kinematics in intermediate-mass YSOs. (2) Use high-density molecular tracers to search for massive, collapsing molecular cores associated with embedded clusters of intermediate-mass YSOs. (3) Examine the interface between ionized and molecular gas in regions like Carina for signs of fragmentation and collapse of cold cores in the path of advancing ionization fronts, especially ionization fronts that have recently left YSO clusters in their wakes.

This work is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0901646.

Splatalogue - Motivation, Current Status, Future Plans

Robin Pulliam (NRAO - CV)

Anthony Remijan (NRAO)

The next generation of powerful radio and millimeter/submillimeter observatories (e.g. EVLA, GBT, ALMA, Herschel) require extensive resources to help identify spectral line transitions. We describe the compilation of the most complete spectral line database currently assembled for this purpose. The Splatalogue is an attempt to collate, rationalize and extend existing spectroscopic resources for use by the astronomical community. Splatalogue is a transition-resolved compilation of the JPL, CDMS, Lovas/NIST, Frank Lovas' own Spectral Line Atlas of Interstellar Molecules (SLAIM), data from the Toyama Microwave Atlas for spectroscopists and astronomers, data from Frank De Lucia's lab at The Ohio State University, new methanol data provided by Li-Hong Xu from The University of New Brunswick, Canada and CH3O13CHO data provided by Isabelle Kleiner and the group from the Laboratoire Interuniversitaire des Systèmes Atmosphériques (which can be found under the "LISA Lines" Line List selection). To these databases we have run diagnostics for overlaps on transitions, frequencies, formulae and chemical names and have come up with a common way to display and designate each individual species. Splatalogue also contains atomic and recombination lines, template spectra, and is completely VO-compliant, queryable under the IVOA SLAP standard. It also recommends one frequency for use by the astronomical community for each observed transition of known astronomical molecules. The details of the database, how users can get access to the database through the php web interface or via an API, and how it will be used for the ALMA archive, observing tool and data reduction packages will be presented.

UV to FIR spectroscopy of proto-planetary disks with HERSCHEL and X-shooter:

Suzanne Ramsay (ESO)

Bill Dent (ESO)
Benjamin Montesinos (CSIC)

ALMA will provide an important insight into the chemical properties of circumstellar disks by permitting the properties of the gas and dust to be determined thanks to be the high spectral and spatial resolution. Multi-wavelength studies of disks, using recent data from the ground and from Herschel, are an important step in preparing for ALMA science programmes. We will present results of observations with the X-shooter instrument on the VLT of targets from the Herschel Key Open Time Programme 'Gas in Protoplanetary Systems'. The goals of the GASPS project are to observe key infrared signatures of gas in disks (CO, [CII], H2O, [OI]) and to determine the physical and chemical conditions in the disks. X-shooter observations extend the limits of astrophysical spectroscopy thanks to the unique simultanoues UV to NIR wavelength coverage offered by this instrument. This makes it perfectly suited to support the GASPS observations with detailed characterisation of properties of the stellar source associated with the disk and with key diagnostics of the disk accretion rate and hot gas component (via infrared lines of molecular hydrogen and CO) in the inner disk.

Using Spectroscopy to Probe the Origin of the Stellar Initial Mass Function

Michael Reid (University of Toronto)

It is generally understood that that the mass function of dusty, compact sources (``cores'') in star forming regions strongly resembles the mass function of young stars. However, the mass function of compact sources seen in CO (``clumps'') is significantly shallower than the mass function of dusty cores. Traditionally, these observations have been interpreted as establishing a meaningful, significant distinction between clumps and cores. This talk will examine the existing evidence for the significance of this distinction between dusty cores and CO clumps, highlight the ways in which the dust and molecular line measurements are incomparable, and discuss strategies for using ALMA to make more accurate measurements of the pre-stellar core mass function.

The Physical Properties of High-Mass Star-forming Clumps: A Systematic Comparison of Molecular Tracers

Megan Reiter (University of Arizona)

Yancy Shirley (University of Arizona)
Jingwen Wu (Harvard-Smithsonian Center for Astrophysics)
Crystal Brogan (National Radio Astronomy Observatory)
Alwyn Wootten (National Radio Astronomy Observatory)
Ken'ichi Tatematsu (National Astronomical Observatory of Japan)

We present observations of HCO+ and H13CO+, N2H+, HCS+, HNC and HN13C, SO and 34SO, CCH, SO2, and CH3OH-E towards a sample of 27 high-mass clumps coincident with water maser emission. All transitions are observed with or convolved to nearly identical resolution (30"), allowing for inter-comparison of the clump properties derived from the mapped transitions. We find N2H+ emission is spatially differentiated towards a few very luminous cores (10 of 27) and the N2H+ integrated intensity does not correlate well with dust continuum flux. We calculate the effective excitation density, neff, the density required to excite a 1 K line in Tkin=20 K gas for each molecular tracer. Molecular tracers with larger effective excitation densities (neff >~ 105 cm-3) appear to correlate more strongly with the submillimeter dust continuum intensity. The median sizes of the clumps are anti-correlated with the neff of the tracers (which span more than three orders of magnitude). Virial mass is not correlated with neff, especially where the lines are optically thick as the linewidths may be broadened significantly by non-virial motions. Median mass surface densities of the clumps are correlated with neff, consistent with mass estimates that are independent of neff and sizes that decrease with increasing neff. Volume density is also correlated with neff indicating the importance of understanding the excitation conditions of the molecular tracer when deriving the average properties of an ensemble of cores.

CO Line Ratios in Nearby Galaxies

Erik Rosolowsky (University of British Columbia Okanagan)

The HERACLES Survey Team
The JCMT Nearby Galaxy Legacy Survey Team

In this contribution, we present the preliminary results of surveying CO line ratios across galactic populations. The past decade has seen a surge in the number of surveys of nearby galaxies observed in the low J rotational lines of 12CO. Several previous studies have used these lines to deduce the properties of the molecular ISM in one or a few galaxies. Our current effort is to combine observations of the largest nearby galaxy surveys to present a comprehensive study of line ratios across galactic environment. We are combining (J=3-2) data from the JCMT Nearby Galaxies Legacy survey with (J=2-1) data from the HERACLES survey at the IRAM 30 m. To obtain a complete sampling of the low-J CO ladder, we are combining with archival (J=1-0) data from previous surveys with the BIMA and OVRO millimetre interferometers and the Nobeyama Radio Observatory 45-m. Our sample includes 17 galaxies which are completely sampled over their inner disks with angular resolution of ~15".

Exploring Core Formation in Perseus B1-E

Sarah Sadavoy (University of Victoria)

James Di Francesco (HIA-NRC)
Stefano Pezzuto (IFSI-Rome)
Philippe André (CEA-Saclay)

A key problem in star formation is understanding how mass is distributed from a large molecular cloud to small dense cores and stars. While gravity plays a key role in the evolution of small structures, the relative contributions from other processes (e.g., turbulence, ambipolar diffusion) remain unknown. To study the processes that form cores, we need to explore a core-forming region. Here, we introduce Perseus B1-E, an anomalous clump in the Perseus Molecular Cloud. Perseus B1-E has high extinction (Av>5) but no visible dense cores or young stellar objects. Recent Herschel maps, however, have shown that Perseus B1-E contains (~1 Jy/beam) substructures at 160 - 500 microns. Thus, Perseus B1-E is an excellent candidate for core-formation in a pristine environment.

Future instruments on SOFIA: exploring synergies with ALMA

Ravi Sankrit (SOFIA/USRA)

B-G Andersson (SOFIA Science Center)
SOFIA Science Team ()

A key aspect of the Stratospheric Observatory for Infrared Astronomy (SOFIA) mission is the plan to update its suite of instruments periodically. These updates would avail of the latest technology and respond to the evolution of scientific questions. It is expected that a proposal call for new instrumentation will be issued by NASA every three years, and that the first of these will be released in early 2011.

There are several areas of scientific interest common to ALMA and SOFIA. A careful consideration of these areas, and the expected contribution of ALMA to each of them could motivate the need for specific instruments on SOFIA, and place requirements on their performance. We present an overview of the science vision for SOFIA and its technical capabilities and we highlight the opportunity to propose for new instruments.

Molecular Chemistry in the Nucleus of NGC6946

Eva Schinnerer (MPIA)

David S. Meier (NMT)
Torsten Boeker (ESA)
Eric Emsellem (ESO)

Multi-transition studies of molecules are routinely used for Galactic objects, however, they have not been feasible for many nearby galaxies before ALMA. Thus the predictive power of chemical tracers in nearby galaxies has not been thoroughly tested yet. In order to start improving on this situation we imaged the central 500pc at 1.6'' (45pc) resolution in the nearby star forming late-type spiral galaxy NGC6946 in over 15 molecular transitions using the IRAM PdB interferometer. As the properties of NGC6946's center are well characterized, it offers the unique opportunity to test and verify the predictive power of chemical tracers in nearby galaxies. The center exhibits a fairly complex but regular geometry: a small 300pc long stellar bar dominates the gas motion and morphology while heavily obscured star formation is present in the central 60pc. This enables us to basically probe embedded star formation, Photon Dominated Regions, and (galactic) shocks all at once. We define a set of useful chemical probes for use in the extragalactic context.

Chemistry, Kinematics and Temperature of the Starless Core TMC-1C

Scott Schnee (NRAO)

Rachel Friesen (NRAO)

TMC-1C is a starless core in the Taurus molecular cloud. We have obtained maps of the gas and dust emission from TMC-1C, from which we can constrain many core properties. GBT NH3 (1,1) and (2,2) maps yield the gas temperature, and when paired with IRAM 30m NH2D data we study deuteration as a function of temperature and density within TMC-1C. We calculate the rotation and infall rates using NH2D and N2H+ maps, and we derive accurate dust properties (mass, temperature, and spectral index) from emission maps spanning the range 1160μm < lamda < 2mm.

Redshift Determination and 12CO Line Excitation Modeling for the Multiply-Lensed Galaxy SMM 10571+5730

Kimberly Scott (University of Pennsylvania)

Z-Spec team
HerMES consortium

We report a redshift of z=2.956 for SMM 10571+5730, a multiply-lensed submillimeter galaxy detected with Herschel/SPIRE in the HerMES Lockman-SWIRE field. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify the redshift of this source from the simultaneous detection of four 12CO emission lines (J = 7-6, J = 8-7, J = 9-8, and J = 10-9). Combining the measured line fluxes for these high-J transitions with the J = 1-0, J = 3-2, and J = 5-4 line fluxes measured with the Green Bank Telescope (GBT) Zpectrometer, the Combined Array for Research in Millimeter Astronomy (CARMA), and the Institut de Radioastronomie Millimetrique (IRAM) Plateau de Bure Interferometer (PdBI), respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full 12CO spectral line energy distribution is well described by warm, low-density gas with T(kin) = 200 K and n(H2) = 1.3x103 cm-3. However, it is possible that the highest J-transitions are radiatively excited by warm gas (potentially close to an AGN), or alternatively are tracing a small fraction of very dense gas in molecular cloud cores, which in either case a single gas component model would not describe the full SLED.

Understanding Galaxy Evolution using Nearby Galaxies from the S4G Survey

Kartik Sheth (National Radio Astronomy Observatory)

Juan Carlos Munoz-Mateos (National Radio Astronomy Observatory)
Taehyun Kim (National Radio Astronomy Observatory)
Mike Regan (Space Telescope Science Institute)
Eva Schinnerer (MPIA)
The S4G team

The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest, homogenous survey of mass and stellar structure in the nearby Universe. The survey is a volume (vradio < 3000 km/s, magnitude (mg < 15.5) and size (D25 > 1') limited sample which consists of over 2300 galaxies of all types and masses, observed at 3.6 and 4.5 microns. The mid-infrared emission traces the old stellar light and contains the fossil evidence of the evolutionary processes that have created the variety of galaxies we see today. In the next decade, ALMA and CCAT will be powerful instruments to study the molecular gas distribution and kinematics in these galaxies. While CCAT will allow us to map the gas and dust in a large number of galaxies, targeted spectroscopic observations with ALMA will provide us with an opportunity to study in detail the gas kinematics within galaxies in a host of environments. I present possible investigations that can be undertaken with ALMA in Early and Full Science to better understand galaxy evolution.

Infrared Spectroscopy in the Nearby Universe       

JD Smith  (University of Toledo)

One half of all the non-primordial radiation produced over the history of the universe has been reprocessed by dust and gas in galaxies into the infrared. Yet we are only beginning to exploit the information encoded in this ;SPMquot;other half;SPMquot; of the energy output of galaxies. Resolved infrared spectroscopy of nearby galaxies -- on physical scales well matched to the processes governing galaxy evolution -- is yielding new insight into the flow of energy between stars, gas, and dust, the process of star formation, and the impact of black hole accretion on the interstellar medium. I will review results from a group of coordinated space surveys targeting a wide range of local galaxies on sub-kpc scales with mid- and far-infrared spectroscopy, and highlight the surprising diversity of dust and gas emission being found across all phases of the ISM.

Hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI*

Paule Sonnentrucker (Space Telescope Science Institute)

D.A. Neufeld (JHU)
T.G. Phillips (California Institute of Technology)
M. Gerin (LERMA)
the PRISMAS consortium

Fluorine exhibits a unique thermochemistry, F being the only atom in the periodic table that can react exothermically with H2 to form a hydride. An implication of this is that HF will be the dominant reservoir of fluorine wherever the interstellar H2/atomic H ratio exceeds ~1 (Neufeld, Wolfire Schilke 2005; Neufeld Wolfire 2009). The recent detections of strong HF absorption along the sight lines to G10.6-0.4, the Orion hot core, and G29.96-0.02, W31C, W49N and W51 indicate that HF may serve as a valuable surrogate tracer for molecular hydrogen within the diffuse interstellar medium, both in the Milky Way and other galaxies. In this work we present Herschel/HIFI observations of HF toward 2 new sources of the PRISMAS (PRobing InterStellar Molecules with Absorption line Studies) Key Program: G34+0.1 and DR21OH.

*Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

A study at millimeter wavelengths of the PDR associated with the GGD14 region

Sandra Treviño-Morales (Centro de Radioastronomía y Astrofísica (CRyA))

Yolanda Gómez (CRyA - UNAM (Mexico))
Álvaro Sánchez-Monge (Universitat de Barcelona (Spain))
Gido Garay (Universidad de Chile (Chile))

Using the Very Large Array We have observed hydrogen and carbon radio recombination lines toward the massive star forming complex GGD14. The GGD14 complex, with a luminosity of 10000 Lsol is embedded in the Monoceros molecular cloud at a distance of 1 kpc. The region is dominated by a cometary ultracompact HII region, ionized by a B0.5 zero-age main sequence star, which appears to be surrounded by a photodissociated region (PDR) clearly seen in carbon recombination lines (CRL) and HI 21-cm emission. The CRL and the 21-cm emission regions associated with GGD 14 appear spatially and kinematically separated. In particular the CRL is located in front of the head of the cometary ionized gas tracing a dense PDR. We consider that this object will allow a detailed study of the PDR in the millimeter wavelengths giving information about the interaction of a recent star formation and its surroundings.

Radio galaxies at 90 GHz

Dharam Vir Lal (Harvard-Smithsonian CfA)

Ralph P. Kraft (Harvard-Smithsonian CfA, USA)
William R. Forman (Harvard-Smithsonian CfA, USA)
William Cotton (National Radio Astronomy Observatory, USA)
Martin J. Hardcastle (University of Hertfordshire, UK)
Christine Jones (Harvard-Smithsonian CfA, USA)

Multi-frequency observations of Fanaroff-Riley (FR) class I and class II radio galaxies demonstrate that the relativistic electron populations have very different energy distributions. In low-power FRIs, low-frequency radio images show morphologies that are dis-similar to the morphologies at high frequencies, consistent with the picture of spectral aging; but in more powerful FRIIs show similar morphologies at low and high frequencies. We will present our preliminary results, in particular the basic radio properties of FRII radio galaxies obtained using the Greenbank Telescope at 90 GHz.

H alpha P delta Lines of Hydrogen in Cool Luminous Stars

George Wallerstein (University of Washington)

Wenjin Huang (University of Washington)

We have been assembling Halpha/Pdelta (P for Paschen) line profiles for a wide range of spectral types. The lines are at 6563 and 10049 Å. The data have been obtained with the Coude spectrograph of the 1.2-m telescope of the Dominion Astrophysical Observatory (DAO). In this presentation we concentrate on stars of type F, G, K, and M. The advantage of using Pdelta to verify models of stellar atmosphere is that departures from LTE are mainly due to the meta-stability of the 2s level. Stars of high luminosity illustrate the differences between LTE and NLTE since collisional effects are reduced as compared with main sequence stars. Profile difference between the Pdelta and Halpha lines and the synthesized LTE line profiles are shown.

Empirical Constraints on Turbulence in Protoplanetary Accretion Disks from High Resolution Spectroscopy

David Wilner (Harvard-Smithsonian CfA)

Meredith Hughes (U.C. Berkeley)
Sean Andrews (Harvard-Smithsonian Center for Astrophysics)
Charlie Qi (Harvard-Smithsonian Center for Astrophysics)
Michiel Hogerheijde (Leiden University)

ALMA's high sensitivity will enable investigations of millimeter lines at much higher spectral resolutions than typically considered today, which provides access to information subtly encoded in line profiles. As an example of this new direction, we present arcsecond-scale Submillimeter Array observations of the CO J=3--2 line from the disks around the young stars HD 163296 and TW Hya at 44 m/s resolution. These observations allow us to place constraints on the turbulent linewidth in the disk atmospheres. We reproduce the observed CO J=3--2 emission using two physical models of disk structure: (1) a power-law temperature distribution with a tapered density distribution following a simple functional form for an evolving accretion disk, and (2) the radiative transfer models developed by D'Alessio et al. that reproduce the spectral energy distribution. Both types of models yield a low upper limit of 40 m/s on the turbulent linewidth (Doppler b-parameter) in the TW Hya system, and a tentative (3-sigma) detection of about 300 m/s in the upper layers of the HD 163296 disk. These correspond to roughly <10% and 40% of the sound speed at size scales commensurate with the resolution. The derived linewidths imply a turbulent viscosity coefficient, alpha, of order 0.01 and provide observational support for theoretical predictions of subsonic turbulence in protoplanetary accretion disks.

Observational tests of methanol formation

Eva Wirström (NASA Goddard Space Flight Center)

Wolf D. Geppert (Physics Department, Stockholm University)
Carina M. Persson (Onsala Space Observatory)
John H. Black (Onsala Space Observatory)
Mathias Hamberg (Physics Department, Stockholm University)
Erik Vigren (Physics Department, Stockholm University)

It has been established that the classical gas-phase production of interstellar methanol (CH3OH) cannot be efficient enough to alone explain observed abundances. According to both theoretical models and laboratory experiments, successive hydrogenation of solid CO on interstellar grain surfaces however, can produce the required quantities of methanol. We have observed emission from the 12C and 13C isotopologues of methanol and C18O towards a sample of massive Young Stellar Objects (YSOs) at different stages of evolution, and demonstrate how the observed 12C/13C ratios and the nuclear spin type ratio in methanol (A/E ratio) have been used as independent observational tests to discriminate between a gas-phase and grain-surface origin of interstellar methanol.

Near-infrared and CARMA Observations of the Confirmed Massive Pre-ZAMS Object Mol 160A

Grace Wolf-Chase (Adler Planetarium)

Michael Smutko (Adler Planetarium)
Reid Sherman (University of Chicago)
Doyal A. Harper (University of Chicago)
Michael Medford (Northwestern University)

We present near-infrared narrow-band and broad-band images of Mol 160 (IRAS 23385+6053) that include a young stellar cluster, two HII regions, and a confirmed massive pre-ZAMS object (Mol 160 A). In addition to diffuse H2 2.12 μm and 2.25 μm line emission that we attribute to fluorescence from Photo-Dissociation Regions (PDRs) surrounding the HII regions, we identify ten H2 2.12 μm Molecular Hydrogen Emission-Line Objects (MHOs) that have no detected H2 2.25 μm counterparts. A comparison of the H2 2.12 μm fluxes with upper limits derived from the H2 2.25 μm observations suggests that the MHOs are due to shocked gas, presumably associated with outflows in this region. Despite the high extinction toward Mol 160 A, we detect two MHOs with apparent separation of ~4" in bipolar orientation about this object. We have also acquired CS, HCO+, CH3OH, and 3 mm continuum observations of Mol 160 A with CARMA. The MHOs are associated with Class I CH3OH masers and high-velocity HCO+ outflow emission, although one MHO is offset about 0.75" from the blueshifted methanol and HCO+ peaks. We detect two MHOs at distances of ~46" and ~49" from Mol 160 A that are oriented along the axis of the large-scale CO outflow, which is distinctly different from the compact HCO+ outflow and CH3OH masers.

Gravitational collapse in high-mass star formation regions: absorption of mm and submm lines

Yuefang Wu (Department of Astronomy, Peking University)

Our understanding about high-mass star formation is still less than that of their low-mass counterparts. Theoretical study shows that the radiation pressure of a forming star can halt spherical infall, preventing its further growth when the forming star reaches 8 Msol. This problem has caused two major theoretical models to be proposed on the further growth of massive stars. One model suggests the mergence of less massive stellar objects, and the other is still through accretion but with the help of disk or outflow. Inflow motions are the key evidence of how forming stars further grow.

To detect collapse signature is more difficult than to detect outflow because collapes occur in internal regions. For high-mass star formation, the environment also adds much complexity to the observation. Absorption spectral lines may facilitate the exploration of gas states in such regions. However it is also difficult to detect absorption line at mm and sub-mm wavelenth bands. Recent technological developments have boosted the search of inflow motion. A number of high-mass collapse candidates were obtained with single dish observations, mostly shown in "blue profile"-red-shifted absorption. An appearance evolution were found for high-mass star formation regions, which shows that the infalling signatures seem more common in regions with developed radiation than in younger cores. It opposes the theoretical prediction and also shows that high and low mass star form may have some fundamental difference. Several cases studied with interferometer confirm such evolutionary tendency. Results seem to favor the accretion model. However, the detailed properties of the infall motions need to be explored. Future work is also needed to further resolve cores and to distinguish among infall, rotation and outflow regions. ALMA is expected to benefit these higher sensitivity and higher spatial resolution studies.

Orion KL: The hot core that is not a "Hot Core"

Luis Zapata (CRyA-UNAM)

Johannes Schmid-Burgk (MPIfR)
Karl Menten (MPIfR)

In this talk I will present the results of recent sensitive molecular line observations at millimeter and sub-millimeter wavelengths made with the Submillimter Array (SMA) towards the famous massive star-forming region Orion BN/KL. These observations plus recent SMA CO J=3-2 and J=2-1 imaging of the explosive flow originating in this region, which is related to the non-hierarchical disintegration of a massive young stellar system, suggest that the molecular Orion "Hot Core" is a pre-existing density enhancement heated from the outside by the explosive event -- unlike in other hot cores we do not find any self-luminous submillimeter, radio or infrared source embedded in the hot molecular gas. The hot molecular gas is either found to form a shell around the strongest submillimeter continuum source. I will discuss briefly more the possibility of having some other hot molecular cores externally heated as in Orion KL.

Early Phases of Massive Star Formation

Qizhou Zhang (Harvard-Smithsonian CfA)

Recent studies suggest that massive stars form in cold cores embedded in massive molecular clumps with typical masses of 1000 Msol and temperatures of 15K. As a protostar gains mass, heating from the star creates a hot molecular core with temperatures exceeding 100K, and an enhanced abundance of complex molecules. While a significant progress has been made toward the understanding of hot molecular cores in which a high-mass protostellar object has already emerged, our knowledge on initial phases of massive star formation remain sketchy. We obtained high resolution observations of a sample of massive molecular clumps with the SMA and VLA, aiming at revealing physical and chemical evolution during the earliest phases of massive star formation. I will present results from these observations and discuss implications to current theoretical ideas of massive star and cluster formation. Unlike hot molecular cores, these cold cores are faint. ALMA will help addressing some of the outstanding questions that begin to unravel with observations using the current generation of (sub)mm interferometers.

 Page last updated 22 February 2011 by GHMS