Building on New Worlds, New Horizons - New Science from Sub-Millimeter to Meter Wavelengths
Building on New Worlds, New Horizons: New Science from Sub-Millimeter to Meter Wavelengths
The New Worlds, New Horizons Decadal Survey
New Worlds, New Horizons
Lynne Hillenbrand (Caltech)
This talk will summarize the process and main results of the Astro2010 Decadal Survey including the overall context of federal funding for astronomy and astrophysics, the state of the profession, and the scientific motivation for and details of the recommended program.
The Astro2010 Science Frontiers
Martha Haynes (Cornell University)
As an integral part of the Astro2010 decadal survey process, five independent NRC committees, the "Science Frontier Panels" (SFPs), were tasked to identify and articulate the scientific themes that will define the frontier of research in the 2010--2010 decade in five separate sub-fields of astronomy and astrophysics. Each panel was asked to call out four central questions ripe for answering and one general area of unusual discovery potential. I will review the SFP process and summarize their principal conclusions.
New Worlds, New Horizons for RMS
Neal J. Evans II
I will review the context, activities, and recommendations of the RMS panel of the Decadal Survey. The fate of those recommendations once they reached the Main Survey committee will be discussed. I will conclude with my views on the outlook and the way forward for RMS projects.
Origins Science Theme
Keynote Talk: Cosmology with Cosmic Microwave Background Measurements
John Carlstrom (U. Chicago)
It is a remarkable time for cosmology. We now have an testable model for the origin and evolution of the universe from its first instants to the present day. The model contains some remarkable components about which we know very little. Baryonic matter accounts for only a few percent of the make-up of the universe, dark matter accounts for roughly a quarter, and the dominant component is the mysterious dark energy which is causing the expansion of the universe to accelerate. The model starts with a period of inflation from quantum fluctuations at extremely high energy and leads eventually to all the splendid structure around us today. Much of the model has been determined from measurements of the cosmic microwave background radiation (CMB). After a brief review of the field, this talk will focus on new measurements or primordial and secondary anteing pursued to test the model and to investigate the nature of dark energy and inflation.
Counting Giants: Cosmology from Massive Sunyaev-Zel'dovich Galaxy Clusters Detected with the Atacama Cosmology Telescope
Felipe Menanteau (Rutgers Univesity)
We have reached the era where microwave surveys such as
the Atacama Cosmology Telescope (ACT) and the South Pole
Telescope (SPT) are reporting the first samples of massive
galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect.
In this talk I will introduce the set of optically-confirmed
galaxy clusters discovered by ACT through the SZ effect as
well as our ambitious program to identify and characterize
the galaxy clusters for the first time. Using counts of
galaxy clusters as a function of mass and redshift in this
sample I will try to address the questions: "How do cosmic
structures form and evolve?" and "What are the connections
between dark and luminous matter?" as clusters provide a
powerful probe of structure growth and cosmology. I will
present the latest constraints on the matter power spectrum
amplitude, σ8, and dark energy equation of state,
w, from SZ cluster counts detected with ACT.
Using High Angular Resolution Sunyaev-Zel'dovich Effect Measurements to Understand the Formation and Evolution of Galaxy Clusters
Brian Mason (NRAO), M. Devlin (U. Penn.), C. Sarazin (U. Va.), S. Dicker (U. Penn.), A. Mroczkowski (U.Penn.)
Galaxy clusters are the largest known virialized objects in the universe, and have proven to be valuable probes of structure formation and cosmology. Until recently, projections of the cosmology that we would learn from cluster surveys were based on simplifying assumptions, such as that the cluster energetics are entirely governed by gravitational collapse. Precise measurements over the past decade, however, have revealed a much richer phenomenology. New instruments --- for instance, ACT, SPT, and PLANCK---are yielding a wealth of new, SZ-selected galaxy cluster samples extending out to high redshift. At the same time, current and planned instruments such as the GBT, ALMA, and CCAT will provide SZ imaging with an order of magnitude better angular resolution than current survey telescopes. These images will provide valuable insights into the physical processes at play in the intra-cluster medium and will help to quantify selection biases which could be inherent in the lower resolution SZ surveys. I will discuss this science in the context of other capabilities over the next decade, illustrating with results from on-going SZE observations being carried with MUSTANG on the GBT, and describe plans for MUSTANG-2, the proposed successor instrument to MUSTANG.
How will the James Webb Space Telescope measure First Light, Reionization, and Galaxy Assembly in the post-Hubble Wide Field Camera 3 Era?
Rogier Windhorst (Arizona State)
We review how the 6.5 meter James Webb Space Telescope (JWST) can measure First Light, Reionization, Galaxy Assembly, building on lessons learned from the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3). We show what combination of area, depth, and wavelength coverage are needed for JWST to detect a sufficient number of First Light objects, and to measure their evolving luminosity function (LF). After its launch, JWST will map the epoch of First Light through Pop III-star dominated objects at redshifts z = 8--20, and its transition to the first Pop II stars in dwarf galaxies at z < 9. JWST will measure the evolution of the steep faint-end of the dwarf galaxy LF at z = 6--12, which likely provided the UV-flux needed to start and finish cosmic Hydrogen reionization.
We will discuss 1) What deep JWST images will look like compared to the Hubble UltraDeep Field (HUDF), given JWST's expected PSF performance; (2) Simulations of what nearby galaxies observed in the restframe UV-optical by HST would look like to JWST at very high redshifts; (3) If ultradeep JWST images will run into the instrumental or natural confusion limits; and (4) To what extent gravitational lensing bias from foreground object halos will affect the search for First Light objects at redshifts z > 8--10. A new generation of algorithms will be needed to automatically detect, measure and classify objects in very crowded, ultradeep JWST fields.
This work was funded by NASA JWST Interdisciplinary Scientist grant NAG5-12460 from GSFC, and grant HST/DD-11359 from STScI, operated by AURA for NASA under contract NAS 5-26555.
The Structure and Evolution of Circumstellar Disks
John Carpenter (Caltech), Andrea Isella (Caltech), Laura Perez (Caltech)
Over the next decade, advances in millimeter and submillimeter astronomy promises to transform our understanding of how circumstellar disks evolve and form planetary systems. The Extended Very Large Array (EVLA) will soon increase its continuum sensitivity by an order of magnitude, the Atacama Large Millimeter Array (ALMA) will provide more than an order of magnitude increase in sensitivity and resolution compared to existing millimeter-wave interferometers, and CCAT will survey thousands of stars to trace the evolution of disks. In this talk, I will review recent observational results on circumstellar disks from CARMA, SMA, PdBI, and Spitzer, and show how the ELVA, ALMA, and CCAT will expand on these results.
Early Phases of Massive Star Formation
Sarah Ragan (MPIA), Edwin A. Bergin (Univ. Michigan), Fabian Heitsch (Univ. North Carolina), David Wilner (SAO)
Although massive stars play a major role in the energetics of the ISM, the conditions under which they form are relatively uncertain. I will present results from recent observational campaigns targeting infrared-dark clouds (IRDCs), which are believed to be the precursors of massive stars and clusters. I will focus on interferometric molecular line observations of dense gas tracers (e.g., ammonia and N2H+) that shed light on the kinematics in dense regions at the earliest evolutionary phases of massive star and cluster formation. Due to large distances to IRDCs, interferometers are needed to resolve individual core structures. These preliminary studies point to promising science for ALMA, with which the full star-forming laboratories can be mapped in much greater detail.
Studies of Starformation in the Early Universe with CCAT
Gordon Stacey (Cornell University)
I will discuss spectroscopic studies of galaxies in the early Universe that can be entertained with the exquisite sensitivity of the CCAT telescope in the submm telluric windows. CCAT is a proposed 25-m telescope designed to operate from 0.2 to 2 mm at the Cerro Chajnantor site in northern Chile. With regards to conference themes, my talk will specifically address the questions: (1) What is the fossil record of galaxy assembly and evolution from the first stars to the present, and (2) What were the first objects to light up the universe and when did they do it? I will focus on the bright far-IR fine-structure lines of abundant atoms and ions including C+ (158 µm), N+ (122 and 205 µm), N++ (57 µm), O (63 and 146 µm), and O++ (52 and 88 µm). Since these lines are collisionally excited, extinction free, and (usually) optically thin, they are important and even dominant coolants for major phases of the interstellar medium, excellent tracers of the physical conditions of the gas, and trace both the strength and hardness of the ambient interstellar UV radiation fields. At redshifts between 0 and 5, these lines are redshifted into the submm windows that are the primary CCAT science bands. Observing these lines from galaxies in this redshift range probes the history of star formation in the Universe from early times---within 1 Gyr of the Big Bang, through the peak of star formation at z ~ 2 to 3 and back down to the modest star formation rates seen in the local Universe. We have begun to sample these lines at high redshift using our ZEUS spectrometer on the CSO, so far detecting 16 sources at z ~ 1 to 2 in the [C II] line, two at z ~ 2.7 in 122 µm [N II] line, and two at z ~ 3 to 4 in the 88 µm [O III] line. The [C II] line predominantly traces dense photodissociation regions exposed to the ionizing starlight from nearby OB stars, but can also arise from the narrow-line region (NLR) enveloping AGN. Within the star formation paradigm, the [C II] line is used to trace the strength and spatial extent of the starburst. Within our redshift 1 to 2 sample, we find that unlike the localized starbursts found in the present day Universe, at the peak of star formation 8 to 10 Gyr ago, bursts of star formation enveloped galaxies, occurring at high rates over kilo-pc scales (Hailey-Dunsheath et al. 2010; Stacey et al. 2010). The [O III] lines trace the hardness of the local radiation fields, and can arise from diffuse H II regions formed by stars, or from the higher density NLR of AGN. In of itself, the [O II] 88 µm line is used to constrain the hardness of the local UV fields, hence most massive star on the main sequence, or the age of the starburst (Ferkinhoff et al. 2010). The [N II] lines together yield the H II region gas densities and mass. Separately, they are used to distinguish the origins of the [C II] line (H II regions or PDRs) and, when combined with [O III], better constrain the radiation field hardness (Ferkinhoff et al. 2011). With receivers similar to ZEUS on the CCAT telescope, one may probe more than a factor of 10 down the luminosity function at any given wavelength than with current facilities enabling studies of Milky-Way like galaxies in these lines to redshifts near 1. Furthermore, these lines are exceptionally bright so that they can be used to find source redshifts with broadband spectrometers on CCAT, enabling follow-up studies of source dynamics and morphology at high spatial resolution with ALMA.
21 cm Cosmology
Miguel Morales (University of Washington)
I will review 21 cm cosmology power spectrum measurements and their promise for Epoch of Reionization observations at high redshift and dark energy measurements at moderate redshifts. Drawing from our current ARAA article, I will review the instrumental and observational advances behind 21 cm cosmology measurements, the challenges they face, and the potential of medium size (or precursor) instruments to perform these observations.
Quasar Probes of Reionization
Ian McGreer (Steward Observatory), Andrei Mesinger (Princeton), Linhua Jiang (Arizona), Xiaohui Fan (Arizona)
Quasar spectra have been interpreted to argue that reionization ends by z = 6 but is ongoing at slightly higher redshifts. We re-examine Keck spectra of z ~ 6 quasars from SDSS using the simple, robust statistic of the covering fraction of dark pixels to derive an upper limit on the neutral fraction at z =5--6. Compared to previous measurements this method is nearly model-independent, and yet we find <xHI> < 0.5 at z = 6.1, comparable to existing constraints. We limit the neutral fraction to be < 20% at z ~ 5; thus without model assumptions, quasar spectra do not provide direct evidence for an end to reionization by z = 5.
I will also discuss ongoing searches for reionization-epoch quasars with bright radio emission, and their prospects for 21-cm absorption studies.
PAPER: Status and Recent Observations
Danny Jacobs (University of Pennsylvania) & Jonathan Pober (UCB)
The Precision Array for Probing the Epoch of Reionization (PAPER) is an experiment to detect the heating and reionization of the IGM through the 21-cm line of neutral hydrogen. Due to cosmological redshifting, the emission from this epoch will be located in a band around 150 MHz. In this two part talk we will discuss PAPER's progress to date as well as review progress towards a survey of the low-frequency sky from our two 32 element PAPER arrays in Green Bank, WV, and the Karoo, South Africa.
Observing Cosmic Dawn with the Long Wavelength Array
Jake Hartman, Judd Bowman (ASU), Greg Taylor (UNM)
The formation of the first stars, galaxies, and black holes---Cosmic Dawn---is the next frontier in observational cosmology. Neutral hydrogen gas dominates the universe during this epoch, and its redshifted 21 cm line encodes unique information about the first luminous objects. The first station of the Long Wavelength Array (LWA), which will be completed around the time of this conference, provides an unprecedented opportunity to detect or meaningfully constrain the sky-averaged 21 cm signature at 20--84 MHz. The station's 256 tied-dipole antennas are well-matched to the frequency range of the strongest predicted feature, an absorption trough at z ~ 20. The wide bandwidth of the LWA covers multiple inflection points in the expected 21 cm signature, which is critical for its identification and interpretation. Finally, the station's digital backend is capable of phasing the antennas to form multiple beams on the sky. By simultaneous forming a science beam that targets a relatively cold region of sky where the Galactic synchrotron foreground is greatly reduced, and a calibrator beam trained on a bright source with a smooth spectrum, we will achieve a lower foreground and a better spectral calibration than single-antenna experiments allow. This work will produce novel beamforming techniques and the precise calibration of the electromagnetic properties of our array, which will be directly applicable to the design and operation of future HERA projects.
The Dark Ages Radio Explorer (DARE)
Jack Burns, Joseph Lazio, Stuart Bale, Judd Bowman, Richard Bradley, Chris Carilli, Steve Furlanetto, Geraint Harker, Avi Leob, Johnathon Pritchard
"What were the first objects to light up the universe, and when did they do it?" (NRC, 2011). These are among the most fundamental questions in modern astrophysics and cosmology as articulated in the recent NRC report, New Worlds, New Horizons in Astronomy and Astrophysics. The Astro2010 Decadal Survey singles out this epoch as one of the top three science objectives for the coming decade. The birth of the first stars and black holes---the end of the Dark Ages or the "Cosmic Dawn"---is one of the truly transformative events in the history of the Universe. It provides the key connection between observations of the extraordinarily smooth Universe 400,000 years after the Big Bang seen via the Cosmic Microwave Background, and telescopic images that reveal the wealth of structures and galaxies seen today. Unfortunately, this epoch has remained tantalizingly out of reach for decades and its exploration requires fundamentally new techniques. With the Dark Ages Radio Explorer (DARE), we will investigate this early epoch of the Universe (~ 80--420 million years after the Big Bang) for the first time using the sky-averaged, redshifted 21-cm Background (z = 10--35) arising from the time when the first stars and black holes appeared in the Universe. DARE consists of a pair of tapered dipole antennas in lunar orbit operating in the RFI-quiet shielded zone above the farside at 40--120 MHz. This satellite takes advantage of significant heritage from ground-based EoR experiments (i.e., EDGES) and previously-flown antennas and receivers that operated at low frequencies. In this talk, we will discuss the science objectives, the instrument package, and the spacecraft that we propose for DARE.
Understanding the Cosmic Order Science Theme
Keynote Talk: A New Cosmic Order
Chris Carilli (NRAO)
One of the most remarkable advances of the previous decade in the study of galaxy evolution has been the detailed delineation of the star formation history of the Universe, and the stellar mass build-up, as a function of redshift, galaxy stellar mass, luminosity, and environment, back to first light and cosmic reionization (z > 6). However, these studies trace essentially the products of galaxy formation. The major goal for studies of galaxy formation in the next decade will be to delineate the "dense gas history of the Universe," i.e., the evolution of the molecular fuel for star formation in galaxies, using RMS facilities. Recent first results in the study of molecular gas in distant galaxies using existing telescopes such as the VLA, GBT, and PdBI, have led to a significant paradigm shift models for the dominant mechanism driving star formation in galaxies over cosmic time. While gas-rich mergers have long been hypothesized as a major driver of cosmic star formation over time, observations of typical z ~ 2 galaxies indicate that star formation is most likely driven by relatively steady, cold mode accretion over longer timescales. It has also been found that the baryonic mass in galaxies during these epochs is dominated by gas and not stars. This represents a fundamental change in galaxy properties during the dominant epoch of stellar mass build up. The coming years will see a revolution in the study of the "gas-dominated Universe," through the remarkable advances of the EVLA and ALMA. Together, these facilities represent an order of magnitude, or more improvement in observational capabilities from 1 GHz to 1 THz.
Exploring the Physics of Galaxy Cluster Mergers and AGN Feedback: Prospects with Emerging Centimeter to Meter Wavelength Instrumentation
Tracy Clarke (NRL)
Clusters of galaxies fill an exceptional role in astrophysics as both laboratories for plasma physical processes as well as key constituents in precision cosmology studies of dark energy.
Galaxy clusters evolve through merger events which drive shocks and turbulence into the intracluster medium. These processes lead to the acceleration or re-acceleration of relativistic particles, the compression of magnetic fields, and heating of the intracluster gas. Merging clusters receive transient boosts of the X-ray temperature and luminosity and are temporarily driven from hydrostatic equilibrium. Inclusion of these systems in precision cosmology studies of dark energy can increase the scatter in the relations. A common feature of these merging systems is the presence of large regions of diffuse synchrotron emission which is stimulated by the energy of the merger. Radio observations in the centimeter to meter wavelength regime can potentially be used to identify merging systems in cluster samples being used for cosmological studies.
Feedback from the active galactic nucleus at the heart of the cluster is thought to be a leading candidate for resolving the 'cooling flow problem' in astrophysics. This radio-mode feedback may also impact the evolution of the massive host elliptical galaxy through the suppression of star formation. The history of AGN energy input into the cluster atmosphere can be traced through low frequency radio studies which can probe multiple generations of outbursts.
We discuss the current and future prospects of using radio interferometers in the centimeter and meter wavelength regime to better understand AGN feedback and the physics of cluster mergers.
The ALFALFA Census of Gas-Rich Galaxies at z = 0
Martha Haynes (Cornell University)
Capitalizing on the huge collecting area of the Arecibo telescope and the survey capability of the Arecibo L-band Feed Array (ALFA), the Arecibo Legacy Fast ALFA (ALFALFA) extragalactic H I 21-cm line survey aims to produce a census of H I-bearing objects found over 7000 square degrees of the high Galactic latitude sky out to z < 0.06. The survey observations are 90% complete and a catalog is available for 40% of the final survey area. Mimicking an effect already known for luminosity functions based on optical catalogs, the low H I mass slope of the H I mass function (HIMF) is much shallower than the corresponding slope expected by ΛCDM for the low mass end of the halo mass function. Interestingly, the low mass slope of the HIMF becomes steeper in H I-rich moderate density environments. In surprising contrast, ALFALFA detects many more such objects than predicted by previous HIMF results, of particular importance since it directly impacts, in a positive sense, estimates of the expected H I detection rate at high z with the SKA and its pathfinders. With its completion, ALFALFA will provide the first robust census of gas-rich halos over a cosmologically significant volume. Our coordinated multiwavelength program will yield important insight into how some massive galaxies maintain huge gas reservoirs without converting their gas into stars and how isolated low mass halos are able to retain some H I gas despite their fragile thermal state and shallow potential wells.
H I Signatures of Galaxy Evolution
Thijs van der Hulst (Kapteyn Astronomical Institute)
Detailed imaging of H I in and around galaxies does provide unique information about the various processes shaping galaxies: merging, cold gas accretion, feedback. I will briefly discuss the evidence that exists from observations of H I in and around galaxies in the nearby universe and summarize the tremendous potential for the Square Kilometre Array and its pathfinders.
Diffuse H I and the Evolution of Galaxies
Felix J. Lockman (NRAO)
Our understanding of the formation, growth and evolution of galaxies is still primitive. In the local Universe, we see evidence in H I emission of galaxy collisions (the M81 group), accretion (the Magellanic Stream) and possibly infall of fresh gas (high-velocity clouds). But so far these phenomena have been studied only at relatively high column densities, typically > 1018 cm-2. A new generation of experiments pushing the NH limit to 1017 cm-2 is likely to give a very different view of the environment of galaxies and groups, and this forms one frontier of galactic research. I will present some preliminary work and discuss future prospects for deep H I emission studies of large areas.
The Atacama Large Millimeter/submillimeter Array
Carol Lonsdale (NRAO)
The Atacama Large Millimeter/submillimeter Array, ALMA, will begin Early Science observations in late 2011 with 16 12-m antennas, and when it is completed in 2013 it will boast a main array of 50 12-m antennas reaching baselines of up to 15 km, a total power array of 4 12-m antennas, and a smaller array of 12 7-m antennas, The Atacama Compact Array (ACA). A global partnership between North America, Europe and East Asia in cooperation with Chile, ALMA is sited at 5000 m in the Chilean Atacama desert. At completion, ALMA will exceed the capabilities of current arrays by orders of magnitude in resolution and sensitivity, and by factors of a few in wavelength coverage and bandwidth. Amongst the key science breakthroughs to be expected with ALMA are the ability to reveal disks and forming protoplanets around nearby stars, image gas and dust from high redshift galaxies, and undertake unparalleled spectral lines studies which will greatly expand the fields of astrochemistry and astrobiology.
Astrophysics with CCAT
Jason Glenn (Colorado), Riccardo Giovanelli (Cornell), Stephen Padin (Caltech), Simon Radford (Caltech), Gordon Stacey (Cornell), Jonas Zmuidzinas (Caltech)
CCAT is a 25-meter diameter submillimeter telescope that we plan to build on a mountain atop the Atacama plateau in Chile. It will have wavelength coverage from 200 µm to 2 mm, with wide-field imaging capability and spectroscopic capability. It will enable new observations over a broad range of astrophysics, from galaxy formation and evolution, to star formation and the interstellar medium in the Milky Way and nearby galaxies, to the solar system. This presentation will focus on the following questions posed by Astro2010 to be addressed by CCAT: (1) "How do baryons cycle in and out of galaxies and what do they do while they are there?" (2) "How do cosmic structures form and evolve?" and (3) "What were the first objects to light up the universe and when did they do it?" CCAT will address the first two of these questions by assessing the dust and molecular gas content of galaxies from the nearby universe to high redshift, bearing on the formation and evolution of galaxies. By measuring the thermodynamic state of the gas in galaxy clusters across a broad range of redshifts via the Sunyaev-Zel'dovich effect, CCAT will address the formation and evolution of galaxy clusters. Submillimeter/millimeter-wave colors and spectroscopy provide a potentially powerful method for selecting very high redshift galaxies, those forming during the epoch of reionization, which addresses the third question. The CCAT telescope and likely first-light instrumentation will be described briefly, followed by a description of the astrophysics to be probed with CCAT.
The CCAT partnership is comprised of Cornell University, the California Institute of Technology, the University of Cologne, the University of Colorado, the Universities of Waterloo and British Columbia, and AUI, Inc.
New Horizons for CARMA
Lee Mundy (University of Maryland); The CARMA Observatory
From the formation and evolution of cosmic structure to the formation of of stars and planetary systems in the local Milkyway, the Combined Array for Research in Millimeter-Wave Astronomy (CARMA) enables studies of the gas and dust content, physical state, kinematic, and evolution. The new 23-element mode for CARMA extends the array's capability for precision, widefield mapping. This opens new avenues for studying: the physics of the hot gas in galaxy clusters and the evolution of galaxy clusters, the global processes that control star formation in galaxies, and the transition to star formation in local galactic molecular clouds. The new full-polarization capability of the array brings a new focus onto the role of magnetic fields on star formation and in galaxies.
Studies of Molecular Gas and Star Formation with the Large Millimeter Telescope
F. Peter Schloerb (U. Massachusetts)
Large, single dish, millimeter-wave telescopes equipped with focal plane arrays for spectral line and continuum observations, can address key scientific questions posed by the New Worlds, New Horizons study. The ability of a large single dish to rapidly image low surface brightness features is especially critical since these are often the best diagnostics of physical conditions in the molecular interstellar medium. In this presentation we review some of the contributions that will be made by such a system in the coming decade.
MM-wave observations of the interstellar molecular gas and dust components in galaxies offer critical information on their structure and evolution. Detailed mapping of nearby (< 100 Mpc) galaxies, particularly through observations of low surface brightness, high density tracers, probes of the physical and chemical processes that link the interstellar medium to the recent and future production of stars as these systems continue to evolve. Within our own galaxy, a large millimeter-wave telescope can provide the sensitive wide field reconnaissance of dust and molecular line emission from giant molecular clouds needed to reveal the physical processes that regulate stellar production. For example, observational measures of the turbulent gas flows demand high spatial dynamic range and high spectral resolution measurements of molecular line emission in order to determine critical spatial scales (Jean's length; sonic scale) related to star formation. Millimeter wavelength bolometer arrays that fill the focal plane can image the dust continuum emission from core regions down to the brown dwarf limit for nearby GMCs that subtend 100 deg2.
EVLA Constraints on the Progenitors of Supernovae Type Ia
Laura Chomiuk (NRAO/CfA), A. M. Soderberg (Harvard), R. Chevalier (University of Virginia), C. Badenes (Tel Aviv University), C. Fransson (Stockholm University)
In response to the Astro2010 science frontier question "What are the progenitors of Type Ia supernovae and how do they explode?", we present our EVLA search for radio continuum emission from Type Ia SNe. In the favored model for these explosions, a white dwarf accretes material from a hydrogen-rich donor star (e.g., red giant). A necessary implication of this model is the production of weak radio emission as the SN blastwave plows through the wind of the donor star. Previous radio searches for this signal have been unsuccessful, largely attributed to the fact that the expected emission lay just beyond the VLA sensitivity. Here we present recent results from our EVLA program, which utilizes the increased sensitivity to search for the expected signal from SNe Ia. The non-detection of radio emission with the EVLA would indicate double-degenerate progenitor systems (binary white dwarf) or require serious modifications to the single-degenerate model.
The Evolution of Molecular Tracers in Galaxies
Juergen Ott
The upcoming decade will revolutionize the observations of molecular gas in galaxies. Molecular gas in the ultimate ingredient to form stars and it is therefore indispensable to fully understand the formation of molecular clouds as well as their collapse into stars if we are to describe galaxy evolution at large. One of the major problems are that cold molecular hydrogen is not observable. Tracer molecules or other methods are required to estimate the molecular structure of the interstellar medium. The upcoming generation of telescopes such as ALMA, EVLA, CCAT, and the SKA with their incredible sensitivities, spectral bandwidth and spatial resolution, will allow us to find, characterize, and map molecular tracers for physical quantities such as gas mass, gas density, temperature, shocks, ionization rates, and magnetic fields. The redshift space that these telescope open up will enable us to study the evolution of these quantities from the era of galaxy formation, via the peak of the star formation density, through the relaxation period, to today's nearby Universe. I will present an overview of the exciting possibilities that are opened up by the next generation facilities in this field.
Intermediate-Mass Black Holes in the Local Universe: Lessons from G1
Joan Wrobel (NRAO), J. E. Greene (University of Texas at Austin), L. C. Ho (Observatories of the Carnegie Institution for Science)
Intermediate-mass black holes (IMBHs) occupy the gap between stellar-mass BHs with masses of ~ 10 Msun and supermassive BHs with masses of ~ 106 Msun or more. Finding IMBHs has key implications for predictions of gravity wave signals, for understanding formation channels for seed BHs, and for testing simulations of gravitational wave recoil. Stellar dynamical searches for IMBHs within the Local Group are possible, but such searches are not free from controversy and have motivated searches for radiative signatures of accretion onto IMBHs. We summarize the lessons learned from dynamical and radiative studies of G1, a globular cluster in M31 that hosts a candidate IMBH with a mass of ~ 18,000 Msun. Beyond the Local Group, stellar dynamical searches for similar IMBHs will be impossible even with planned 30-meter class ground-based telescopes. We examine the prospects for using RMS and X-ray facilities to find a population of G1 analogs in the local Universe.
Tracing Molecular Material from Circumstellar Envelopes into the Diffuse ISM
Lucy Ziurys (Univ of Arizona, Steward Observatory), Jessica Dodd (University of Arizona), Lindsay Zack (University of Arizona), Nick Woolf (University of Arizona)
A series of millimeter-wave observations are being conducted that trace the history of molecular material from circumstellar envelopes of evolved, dying stars into planetary nebulae, and then into diffuse clouds using the telescopes of the Arizona Radio Observatory (ARO). The molecular inventory of both carbon and oxygen-rich circumstellar envelopes has been established through several on-going spectral line surveys of a number of carbon and oxygen-rich stars, including NML Cygnus. Key molecules found in these objects have subsequently been sought in planetary nebulae, the next stage of stellar evolution. Several molecules, such as H2CO, HCO+, C3H2, as well as CO and CS have been found in very old planetary nebulae including the Ring and the Helix; a similar set of molecules have been discovered in diffuse gas. These data suggest that gas-phase molecules formed in circumstellar envelopes survive the planetary nebula phase and consequent transport into the diffuse ISM, seeding the chemistry of dense clouds. Such molecules are also likely to be clues to the origin of the diffuse interstellar bands.
The Power of Radio Active Stars
Rachel Osten (STScI)
The decadal survey identified several questions which stellar radio observations can address (How do stars form? How do circumstellar disks evolve and form planetary systems? How do rotation and magnetic fields affect stars?), and stellar radio observations are relevant to two discovery areas as well (time-domain astronomy and astrometry). Due to the fact that a variety of mechanisms contribute to stellar radio emission, the entire gamut of radio wavelengths is useful for answering these questions, from long wavelengths (decimeter-meter wavelengths) to the shortest radio wavelengths (millimeter-sub-millimeter wavelengths). In the last several years there has been a revival of interest in stellar radio observations due partly to the development of new capabilities and partly to new discoveries. These discoveries range from detection of pulsating radio emission in ultracool dwarfs and the consequent implications for magnetic fields on such objects, to observations of mm variability by energetic particles in young stars which has implications for disk chemistry and ionization. I will discuss a multiwavelength observing program of stars in the cool half of the HR diagram which can address these questions.
Solar Physics with the Frequency Agile Solar Radiotelescope (FASR)
Tim Bastian (NRAO), D. E. Gary (NJIT), G. J. Hurford (U.C., Berkeley), S. M. White (USAF), & FASR team
Solar activity represents a uniquely accessible example of the ubiquitous processes of energy release and particle acceleration that occur in a wide range of contexts, from the magnetosphere to the galaxy. Radio observations provide both a unifying perspective on solar activity and a unique sensitivity to solar magnetic fields, the energy source for solar activity. In addition, radio emission is unsurpassed in its sensitivity to accelerated particles. As a result, radio emission provides a powerful source of diagnostic information with the potential for transformational insights into solar activity and its terrestrial impacts. The same processes that convert magnetic energy to accelerated particles during solar activity occur in many other astrophysical contexts, and what we learn of these processes from solar radio studies is directly applicable to them.
The Frequency Agile Solar Telescope (FASR) is an innovative radioheliograph designed to fully exploit radio diagnostics of physical processes on the Sun. In particular, FASR will perform dynamic, broadband, imaging spectroscopy. In doing so, it will address a number of pressing science objectives include, but not restricted to: coronal magnetic fields, magnetic energy release and particle acceleration, drivers of space weather, and the quiet solar atmosphere.
This talk will briefly introduce the instrument and review the main science objectives. Time permitting, the operational model of this facility will be also be discussed.
Frontiers of Knowledge Science Theme
Keynote Talk:
Sarah Church (Stanford)
Probing Inflation and Neutrinos by measuring the CMB polarization with ABS, ACTPol, and SPTPol
Michael Niemack (NIST)
Upcoming measurements of the cosmic microwave background (CMB) polarization anisotropies will probe the physics of inflation by searching for the signature of inflationary gravitational waves and measuring the tilt of the polarization anisotropy power spectrum. This is a direct probe of physics near the grand unification energy ~ 1016 GeV. In addition, measurements of the gravitational lensing of the CMB as well as the high-multipole polarization power spectrum have the potential to constrain the sum of the neutrino masses with 0.05 eV precision through the effects of neutrinos on large-scale structure and the helium abundance at recombination. The neutrino mass-splitting observed by atmospheric neutrino oscillation experiments is 0.05 eV, so this precision should provide a measurement of the sum of the neutrino masses and could allow differentiation between normal and inverted neutrino mass hierarchies. Measurements of the CMB lensing deflection field will also allow characterization of the matter power spectrum at z ~ 3, and thereby improve dark energy constraints from lower redshift surveys.
We are developing feedhorn-coupled transition-edge-sensor polarimeter arrays that will be deployed in three upcoming CMB polarization experiments: the Atacama B-mode Search (ABS), the South Pole Telescope Polarimeter (SPTPol), and the Atacama Cosmology Telescope Polarimeter (ACTPol). We describe the large- and small-angular-scale CMB polarization science goals and highlight some of the differences among these experiments.
First Results from the Q/U Imaging ExperimenT (QUIET)
Jonathan Zwart (Columbia University)
The Q/U Imaging ExperimenT (QUIET) is a large-angular-scale telescope designed to measure the polarization of the cosmic microwave background from the Atacama Desert, Chile, and to place direct, competitive limits on the tensor-to-scalar ratio (which parameterizes primordial inflationary B modes) using solely polarization information.
We have used QUIET to observe ~ 1000 deg2 of low-foreground sky at 43 (Q band) and 95 GHz (W band) between October 2008 and December 2010, collecting some 10,000 hours of data in that time. The integrity of the Q-band data analysis has been verified with an extensive suite of jackknife tests for nullity, and by comparing results from two independent (and blind) analysis pipelines.
I shall give an overview of QUIET and present the first power-spectrum results from the Q-band data set, including the E-mode power spectrum, a limit on the tensor-to-scalar ratio, and the detection of polarized Galactic synchroton emission away from the Galactic plane. I shall also outline prospects for the use of coherent technology in future projects.
Cosmological Galaxy Surveys: The Molecular Perspective
Steven Myers (NRAO)
Cosmological galaxy surveys in the radio to submillimeter wavebands have traditionally focused on neutral hydrogen surveys using the redshifted 21 cm line below 1.4 GHz, or millimeter and submillimeter observations of dust and molecular tracers. The advent of the EVLA has now enabled wide-band centimeter wave observations of redshifted CO and other lines in the 1--50 GHz range. Observations this decade will complement H I observations by the SKA precursors such as ASKAP and MeerKAT, and in particular those by ALMA---the centimeter-wave band probes regions of high density and obscuration as well as high redshift. A centimeter-wave galaxy redshift survey at z > 1 is within reach of current instruments due to the strength of the molecular transitions compared to the weak H I line, as demonstrated by detections of CO out to z > 6. A future large survey (and detailed follow-up thereof) would enable a wealth of science touching on many of the key questions posed at this meeting including: How do cosmic structures form and evolve? What is the fossil record of galaxy assembly and evolution from the first stars to the present? How do baryons cycle in and out of galaxies and what do they do while they are there? Why is the universe accelerating? This survey would supplement optical/IR galaxy surveys probing cosmology through baryon oscillations, while also giving us a window into the molecular and stellar processes characterizing the gastrophysical Universe. In order to fully exploit the future science potential of such a survey, further development and enhancement of these capabilities is planned through expansions of our EVLA and VLBA network of telescopes under the North America Array program, which is targeted for Astro2020 and beyond.
A Pulsar Trifecta for the Galactic Center: Gravity, Dark Matter, and Populations
Jim Cordes (Cornell), Julia Deneva (NAIC), Michael Kramer (MPIfR), Joseph Lazio (JPL, SPDO), Norbert Wex (MPIfR)
The Galactic center (GC) provides unique opportunities for addressing questions raised in New Worlds, New Horizons. Timing of pulsars around Sgr A* is a particularly powerful means for probing matter and magnetic fields around the supermassive black hole and testing theories of gravity in the strong-field regime. While no pulsars are known yet that are within a few parsecs of Sgr A*, the existence of a large number of circum-BH pulsars can be inferred from the presence of NS progenitors, from the supernova rate, and from the handful of pulsars found nearby. We discuss the challenges for periodicity and single-pulse surveys of the GC, including plasma scattering and dynamical effects, which guide the choices of search frequencies and search algorithms. Follow-up timing on even canonical one-second pulsars can determine masses through measurement of post-Keplerian effects, including apsidal advance, the Shapiro delay and gravitational redshift in binary pulsars, and frame dragging from the spin of Sgr A*. Measurement of the spin and quadrupole moment can aid a precision test of the "no-hair" theorem for black holes (BHs). Fast geodetic precession for orbits < 100 hr will induce some objects to appear intermittent on time scales less than a year. Newtonian contributions to apsidal motion and stochastic orbital perturbations constrain the distribution of smoothly-distributed dark matter and the population of other compact objects, respectively. We compare the efficacy of pulsar timing with that of astrometry and spectroscopy of infrared stars for describing the GC. We describe a program that entails an imaging survey followed by a periodicity and transient search of appropriate targets. Relevant telescopes include the GBT, the EVLA, MeerKAT, and the SKA.
The Event Horizon Telescope: (sub)mm VLBI of Sgr A* and M87
Sheperd Doeleman (MIT Haystack Observatory)
Recent technical and scientific progress in Very Long Baseline Interferometry (VLBI) at mm/submm wavelengths now makes it very likely that we will be able to observe and resolve a black hole event horizon within this decade. Over the next few years, new facilities, including ALMA, will join current (sub)mm VLBI arrays, creating a high sensitivity "Event Horizon Telescope" (EHT) capable of angular resolutions approaching 20 µas. For Sgr A*, the super massive black hole at the Galactic Center, and M87, the black hole powered core of a giant elliptical galaxy, these angular resolutions correspond to the Schwarzschild radius. Achieving this goal would open a new window on the study of General Relativity (GR) in the strong field regime, accretion and outflow processes at the edge of a black hole, relativistic jet genesis, and fundamental black hole physics. Recent 1.3 mm wavelength VLBI observations of both these sources confirm the existence of structure on event horizon scales, and for Sgr A*, time variability of emission on these scales has now been detected. Enhancing the current (sub)mm VLBI array to enable imaging of these objects and time resolution of flaring structures will require technical development, but the needed improvements are modest in scope and relatively straightforward, making this a very tractable project. The work includes continued improvement in the bandwidth of VLBI backend systems, development of phased array systems to combine the collecting area of connected element arrays, deployment of modern ALMA-quality receivers, development of new (sub)mm VLBI sites, and migration to wideband software VLBI correlators.
X-ray--Radio Connections
D. Schwartz (CfA)
X-ray and radio radiation are intimately connected via their common origin from relativistic electrons. I will discuss how Chandra X-ray observations, surprisingly, have synergized with radio data to reveal interactions and energetics within cluster of galaxies, and to estimate the properties of relativistic jets emitted from powerful radio galaxies and quasars. Both topics relate to the physics of supermassive black holes, and to their formation and evolution in the early universe. Chandra will continue these studies; however, with the large area of the IXO observatory as recommended by the decadal panel, discovery space opens for the detailed physics of feedback and for cosmological studies using the Sunyaev-Zel'dovich effect.
Early NWNH Science with Pan-STARRS and the outlook for the Decade
Kenneth Chambers (UH Inst for Astronomy, Pan-STARRS)
PS1, the Pan-STARRS Telescope No. 1 has been taking science quality data for more than a year, and the PS1 Science Mission began formally on May 13, 2010. The operations of the PS1 System, including the Observatory, Telescope, 1.4 Gigapixel Camera, Image Processing Pipeline, PSPS relational database and science specific software clients are presently funded through 2012. We are proposing for request NSF support for operations for 2013 to be followed by support for serving the images and database to the community.
The PS1 Surveys include (1) A 3π Steradian Survey, (2) A
Medium Deep survey of 11 PS1 footprints spaced around the
sky; (3) A solar system survey optimized for Near Earth
Objects, (4) a Stellar Transit Survey; and (5) a Deep Survey
of M31. As of February 2011, the 3π Survey has obtained 2 to
4 images × 5 bands (grizy) over the entire sky
north of δ = -30 or 30,000 deg2, consisting of
nearly a petabyte of imaging data.
The coverage, cadence, and data quality of the surveys and the current and expected future performance of the Pan-STARS System will be presented together with Early Science results from PS1 to address how PS1 and Pan-STARRS will contribute to the science described in New Worlds, New Horizons over the coming decade. In particular the synergy with Radio, Millimeter, and Sub-millimeter astronomy will be discussed.
PS1 operations are funded by the PS1 Science Consortium consists of The Institute for Astronomy at the University of Hawai'i in Manoa; the Max Planck Institute for Astronomy, Heidelberg, and the Max Planck Institute for Extraterrestrial Physics, Garching; The Johns Hopkins University; the University of Durham; the University of Edinburgh; the Queen's University Belfast; the Harvard-Smithsonian Center for Astrophysics; the Los Cumbres Observatory Global Telescope Network Incorporated; the National Central University of Taiwan; and the NASA NEOO program.
A Brief Overview of LSST
Zeljko Ivezic (University of Washington/LSST)
The Large Synoptic Survey Telescope (LSST), the top ground-based priority in Astro2010 Decadal Survey report, will carry out an imaging survey covering the sky that is visible from Cerro Pachon in Northern Chile. The LSST design, with an 8.4 m (6.7 m effective) primary mirror, a 9.6 deg2 field of view, and a 3.2 Gigapixel camera, will allow about 10,000 square degrees of sky to be covered using pairs of 15-second exposures twice per night, every three to four nights on average, with typical 5σ depth for point sources of r ~ 24.5 (AB). With about 1000 observations in ugrizy bands over a 10-year period, these data will enable a deep stack reaching r ~ 27.5 (5σ, point source) and faint time-domain astronomy. The measured properties of newly discovered and known astrometric and photometric transients will be publicly reported within 60 seconds after closing the shutter. The resulting hundreds of petabytes of imaging data will be made available to the U.S. and Chilean communities for scientific investigations ranging from the properties of near-Earth asteroids, to characterizations of dark energy from strong and weak lensing, galaxy clustering, and distant supernovae. These data will represent a treasure trove for follow-up programs using other ground and space-based telescopes, such as fast-response fast-cadence photometric observations, spectroscopy and polarimetry, as well as for facilities operating at non-optical wavelengths and for gravitational wave programs.
Discovery Science Theme
Keynote Talk: Data Discovery and Access for the Next Decade
Robert Hanisch (STScI/VAO)
The telescopes and instrumentation planned for the coming decade are diverse in wavelength coverage and types of instrumentation, but are common in producing data volumes that will dwarf our discipline's current holdings. The potential for new discoveries is high in the intersections between multi-wavelength observations and in the comparisons between simulations and observations. Because the data collections of the next decade will be too large to download and manipulate for individual scientists, distributed data management, intelligent visualization, and server-side deployment of filtering, analysis, and cross-matching algorithms will be essential. I will describe the current capabilities for data discovery and access as provided by the Virtual Observatory, and discuss how the challenges of "big data" might be addressed in the coming years.
Wide Field Radio Transient Surveys
Geoffrey Bower (UC Berkeley)
The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, serendipitous discovery and results from limited surveys indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenonmena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The new generation of centimeter-wave radio telescopes such as the ATA, EVLA, ASKAP, and MeerKAT will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the Square Kilometre Array. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars. While probing the variable sky, these surveys will also provide unprecedented information on the static radio sky. I will present results from three large ATA surveys (the Fly's Eye survey, the ATA Twenty CM Survey (ATATS), and the Pi GHz Survey (PiGSS)) and several small ATA transient searches. Finally, I will discuss the landscape and opportunities for future instruments at centimeter wavelengths.
Low Frequency Time Domain Astronomy with the LWA
Steven E. Tremblay (U. New Mexico), Gregory B. Taylor (U. New Mexico), Jacob M. Hartman (Eureka Scientific), the LWA Collaboration
Traditional radio telescopes use dishes with high forward gain and consequently have little sensitivity outside the "primary beam," which covers a small fraction of the sky. The transient Universe has therefore been largely unexplored at radio frequencies. Since low-frequency instruments, such as the Long Wavelength Array, instead utilize dipole antennas the entire sky becomes simultaneously observable to these telescopes. The implementation of this radio transient surveying capability is well timed to give contemporaneous observations with other recent and forthcoming astronomical survey instruments (e.g., Fermi, LSST, Pan-STARRS, LIGO). Radio transient detection and analysis will commence using our first station (LWA1) equipped with a prototype all-sky imager (PASI) "back end," which will be capable of correlating and imaging all 256 dual-polarization dipoles within the station in real time. The variety of time-varying sources we expect to detect is large and includes high impact science target such as extra-solar planets (i.e., hot Jupiters), rotating radio transients (RRATs), prompt emission from gamma-ray bursts, and pulsar giant bursts. Additionally, the all-sky monitoring capability will allow discovery of currently unknown sources of time-variable low frequency radio emission.
Astrometry: What Does RMS Have to Offer?
Mark Reid (Harvard-Smithsonian CfA)
Recent advances in astrometry with VLBI have resulted in near micro-arcsecond accurate trigonometric parallax and proper motion measurements for compact sources throughout the Milky Way. We are now poised to directly measure the full 3-dimensional locations and motions of massive star forming region in the Milky Way and, for the first time, to map its spiral structure. This will also yield the fundamental parameters of the Milky Way, R0 and Θ0, which are key to determining the mass of the Galaxy and the fate of Magellanic Clouds. Also, accurate distances to X-ray binaries can now be measured, providing the key to unlock details of the physical parameters of the binary members, including measurement of black hole spin and the neutron star equation of state.
Galaxy Motions with Radio Astrometry
Andreas Brunthaler (MPIfR), Mark Reid (CfA), Karl Menten (MPIfR), Geoff Bower (UC Berkeley), Jeremy Darling (Colorado), Heino Falcke, Michael Garrett, Christian Henkel, Abraham Loeb, Laurent Loinard, Tom Oosterloo, Elke Roediger, Lorant Sjouwerman, Andrea Tarchi, Jacqueline van Gorkom
Most galaxies in the universe are not isolated objects, but are found in groups or clusters. Thus, large scale structure formation and galaxy formation are closely connected topics. In the concordance ΛCDM cosmological model, galaxies grow hierarchical in mass by accreting smaller galaxies, and the flow of galaxy groups and clusters is strongly connected to the distribution of (dark) matter in large scale structures. High precision astrometry, identified as one of the discovery areas in the Decadal Survey, can significantly contribute to this field by measuring the 3 dimensional space motions of galaxies in the local volume. With current instrumentation (i.e., the Very Long Baseline Array, VLBA) we can already measure motions of galaxies with accuracies of a few microarcseconds per year, as shown by our measurements of M33 and IC 10. These studies are currently extended to measure the proper motion of M31, M81, and M82 in the M81 group of galaxies, and even galaxies in the Virgo galaxy cluster. The VLBA sensitivity upgrade, and eventually the Square Kilometer Array with enough sensitivity on long baselines, will dramatically improve this work by (i) increasing the number of target sources (e.g., weak radio cores and methanol masers), and (ii) improving the astrometric accuracy due to the availability of more and closer reference sources.
The Proper Motion of the Andromeda Galaxy: The Keystone of Local Group Dynamics
Jeremy Darling (University of Colorado)
Astrometry in the Galactic neighborhood was identified as one area of unusual discovery potential by the 2010 decadal survey committee. To address this topic, I will present the recent discovery of water masers in the Andromeda Galaxy (M31) and discuss the future plans for precise astrometry using these masers to measure the proper motion M31. The proper motions of maser complexes will indicate (1) the transverse velocity of M31 on the sky, providing its full three-dimensional velocity, and (2) the geometric distance to M31 via proper rotation, limited primarily by uncertainties in the rotation profile of M31 and peculiar maser motions. These measurements will jointly address the future evolution of the Local Group, whether or not the Local Group forms a bound system, and the total mass of the system (which in turn constrains the dark matter component and its distribution).
Laser Interferometer Space Antenna
Joan Centrella (NASA/GSFC)
The Laser Interferometer Space Antenna (LISA) is a space-borne observatory that will open the low frequency (~ 0.1--100 mHz) gravitational wave window on the Universe. LISA will observe a rich variety of gravitational wave sources, including mergers of massive black holes, captures of stellar-mass black holes by massive black holes in the centers of galaxies, and compact Galactic binaries. These sources are generally long-lived, providing unprecedented opportunities for multi-messenger astronomy in the transient sky. This talk will present an overview of these scientific arenas, highlighting how LISA will enable stunning discoveries in origins, understanding the cosmic order, and the frontiers of knowledge.
A Pulsar Timing Array for Gravitational Wave Detection
Paul Demorest (NRAO); NANOGrav collaboration
Gravitational wave (GW) astronomy was chosen as one of five key discovery areas for the next decade by the Astro2010 decadal survey. High-precision pulsar timing experiments are sensitive to GW in the nanohertz frequency regime, a concept known as a pulsar timing array. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has been pursuing this goal for the past five years using existing large US radio telescopes (the GBT and Arecibo). In this talk I will give an overview of the NANOGrav project, and present our current results. I will also discuss potential improvements over the next decade, including how existing, soon-to-exist, and proposed new radio facilities might best benefit pulsar timing array projects such as NANOGrav.
Implementing the Program
The View from the National Science Foundation
James Ulvestad (NSF)
Up the (Radio) Decade: RMS in the First 50 Years of Decadal Reviews
Virginia Trimble (UC Irvine & LCOGT)
Starting in 1962, the American astronomical community has attempted, at the request of the NAS and at 10-year intervals, to prioritize the observational (etc.) facilities they feel will be necessary to carry out the most important science in the next decade. A book editor asked me a few months ago to find out what had happened to all the requests and predictions of the past. The talk will report what I learned in the RMS sector. There have, of course, been some spectacular successes (especially the VLA), some territories long ceded to Europe and private observatories, and at least one major failure (no one asked for COBE!). Each decadal report except the first has suggested more money should go on the ground (mostly NSF), meaning less into space (NASA mostly), and that more federal funding should go to optical astronony, and so less to radio astronomy. These things haven't really happened. Many predictions about the community have been wildly optimistic.
Science Opportunities with EoR Arrays
Colin Lonsdale (MIT Haystack Observatory)
The proposed HERA program involves the design, construction and use of low frequency arrays to study the redshifted 21 cm line of neutral hydrogen during the cosmological epoch of reionization (EoR). Such arrays will operate at meter wavelengths and longer, and will be based on large numbers of simple broadband antennas. The arrays will be designed for excellent imaging properties, high precision calibration, and flexible data processing.
These same properties will make HERA arrays potentially powerful for a wide range of non-EoR scientific investigations, either as-is, or at modest incremental cost. In this contribution, these potential applications are reviewed in the context of the likely characteristics of forthcoming HERA array designs.
Roadmap to Discoveries in the New World
Sander Weinreb (Caltech)
This week you have heard of many exciting opportunities for observations in the radio range. Will there be sufficient radio instruments for US astronomers to implement these opportunities? I think not and want to provide a skeleton plan of how to do so in the cm wave range.
I believe we need to start with a two year phase of development and prototyping of an array which is of order of 256 × 6 m antennas operating in the 0.3 to 10 GHz range with all these parameters subject to extension or reduction as part of this first phase. The array should be cost capped at $75M which we expect can be funded by a combination of private and government funds. I believe this design phase will cost $4M and can be immediately be funded by not building SKA Dish Verification Antenna #1 (DVA-1) at this time, by a 1/3 gift from the Allen Foundation, and by in-kind contributions, mainly from NRAO.
Let me address some of the controversial points:
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Not building DVA-1 at this time---I do not see the point of building an offset 15-m antenna very similar to what is planned 36-fold for Meerkat. We and the Canadians should pool our efforts to insuring success of the Meerkat antenna.
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All observation that can be made with this array could be performed with existing instruments---This may be true but is the observing time available? I see that 40,000 hours of Meerkat time have already been allocated and most to this time is to non-US astronomers. We need a world-class survey instrument which is available to US astronomers.
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Cm wave technology is old-hat and the US does not need to continue technology development. I believe that we can ride the crest of cm wave developments in the vast wireless communication arena and produce large arrays at a fraction of cost of old technology. In recent months I have heard of correlator technology which consumes 30 times less power per operation than ALMA and EVLA correlators. In the front end area by using wide bandwidth and not requiring cooling below 2 GHz we can build receivers at a tenth of the cost of the EVLA receivers.
New Worlds, New Horizons, New Capabilities, and New Discoveries
Kenneth Kellermann (NRAO)
While the Astro-2010 report lays out Discovery Areas and Frontier Science Questions, the historical advances in astronomy, especially in radio astronomy, have been the result of using new instruments with better sensitivity, angular, spectral, or time resolution, and the utilization of these new capabilities by scientists willing and able to distinguish new phenomena from instrumental effects. Experience suggests the excitement of new facilities is not only in the old questions that they may answer but in the new questions raised by the new observations. Cosmic radio emission itself, the evolving universe, radio galaxies, quasars, pulsars, Jupiter and solar radio bursts, Jupiter's radiation belts, the rotation of Mercury, gravitational lensing, GRBs, Dark Matter, the CMB, etc. were all discovered as a result of observations that were motivated by other goals, including military and communications research. Yet, these unanticipated and unplanned discoveries today define the climate of modern astrophysical research.
I will discuss what opportunities may exist for new
discoveries in radio astronomy with only moderate investments
in new construction and operational expenses.
Posters
Probing Cosmic Structures using the LMT
Min Yun (U. Massachusetts)
The large collecting area of the Large Millimeter Telescope (LMT) and its suite of powerful instruments are designed specifically to address the formation and evolution of massive galaxies over the cosmic history. We will discuss how the high resolution continuum surveys at mm/smm wavelengths using the AzTEC and the next generation bolometer cameras and the Redshift Search Receiver systems can lead to a precise determination of the formation and evolution of cosmic structure during the first few billion years to the present epoch, including the formation of the first massive galaxies and the connection between dark and luminous matter. We will also discuss the role of the LMT as the premier survey facility and target finder for the new powerful imaging facilities such as ALMA and EVLA during the next decade.
ALMA in the Decade: A Development Program for the Future
Al Wootten (NRAO), Todd Hunter (NRAO)
ALMA will transform astronomy beginning with Early Science results later this year. It will reach full operation by 2013 and will eclipse any current millimeter or submillimeter array in its sensitivity and resolution by nearly two orders of magnitude. ALMA will operate from 3 mm to 0.3 mm across a decade of nearly complete frequency access as enabled by its broad bandwidth receivers and spectacular site. Having invested ~$1.3B to realize the biggest historical advance in ground-based astronomy, it is vital to plan how to maintain and expand its capabilities. For example, ALMA's design allows for expanding the number of antennas in the 12-m Array from 50 to a full complement of 64 which would maximize imaging speed. Also, ALMA's wavelength coverage could be extended to cover from 1 cm to 200 µm and thereby encompass additional unique spectral features and important scientific topics. The ALMA Operations Plan envisaged an ongoing program of development and upgrades. With a modest investment of less than 1% of capital cost per year divided among the three funding executives, ALMA will lead astronomical research through the 2011--2020 decade and beyond. Several programs which spearhead a development plan have been identified by the scientific community. We provide the scientific motivation for a suite of key science goals driving possible development projects, along with the relevant technical details.
FASR and Solar/Stellar Magnetic Fields
Stephen White (USAF)
A primary science objective of FASR is to measure magnetic fields in the solar atmosphere, and to use those measurements to further our understanding of the energy releases that produce flares, mass ejections and particle acceleration. There is a surprising number of ways in which radio data can be used to measure magnetic fields on the Sun. This talk will describe those techniques, and then discuss how the solar measurements contrast with radio evidence for the structure of magnetic fields in the atmospheres of other active stars.
CARMA Technical Developments on the Horizon
Nikolaus Volgenau (Caltech), John Carpenter (Caltech), David Woody (Caltech), John Carlstrom (U. Chicago), David Hawkins (Caltech), Lee Mundy (University of Maryland)
The Combined Array for Research in Millimeter-wave Astronomy (CARMA) is pursuing a number of significant technical developments over the next three years. The backend electronics will be restructured to allow the entire 8 GHz IF bandwidth to be processed. The current (analog) downconverters will be replaced with commercially-available ADCs, which will digitize the 1--9 GHz IF bandwidth at a rate of 20 Gsps. A bandformer will then break-up the IF into 8 independently tunable sub-bands, allowing the simultaneous observation of molecular lines in narrow bands with continuum emission in wide bands. In addition, all of CARMA's antennas will be equipped with 1 cm (26--36 GHz) receivers.
These developments are ongoing. Their completion will enable CARMA to operate as a 23-element interferometer in both the 1 cm and 3 mm wavebands with a maximum bandwidth of 8 GHz. By expanding from 15 to 23 elements, the number of CARMA's baselines wil increase from 105 to 253. CARMA will be able to thoroughly sample the sky in a wide range of angular scales, from 9.8 arcminutes to 1.2 arcseconds at 1 cm and from 3.3 arcminutes to 0.4 arcseconds at 3 mm. The benefits to CARMA's sensitivity and imaging speed and fidelity will significantly enhance its ability to pursue scientific projects that address the Astro2010 Decadel Survey's "science frontier" questions.
A Prototype 150 GHz Heterodyne Receiver Module for Large-Scale Astronomical Instruments
Patricia Voll (Stanford University), Lorene Samoska, Todd Gaier, Pekka Kangaslahti, Mary Soria (Jet Propulsion Laboratory), Sarah Church, Judy Lau, Matthew Sieth (Stanford University), Sami Tantawi, Dan Van Winkle (SLAC National Accelerator Laboratory)
The atmospheric window centered around 150 GHz is an important frequency band for many astronomical measurements using ground-based instruments. ience applications include spectral line studies, separating the cosmic microwave background (CMB) radiation from foregrounds, and detecting the hot gas around galaxy clusters using the Sunyaev-Zel'dovich effect. Receiver arrays utilizing High Electron Mobility Transistor (HEMT) technology with excellent noise and scalability have been manufactured up to around 100 GHz. Due to recent improvements in bandwidth and noise temperature, it is now feasible to consider higher frequency receivers with this technology. A compact, wide-band, heterodyne receiver module has been designed to operate in the 140--180 GHz band using HEMT Monolithic Microwave Integrated Circuit (MMIC) InP Low Noise Amplifiers. These amplifiers, along with a second harmonic mixer, bias circuitry, filter, and connectors, are integrated into a single, split-block housing approximately one inch cubed in size. Preliminary cryogenic tests have measured an average system noise temperature of 87 K and average gain of 22 dB over a band from 140 to 180 GHz. A spot noise temperature of 58 K has been measured at 166 GHz. Development of a 4-element array to demonstrate the scalability of these receivers is currently underway, and will serve as a proof-of-concept for much larger arrays with hundreds of elements for astrophysical applications.
Technology Developments for a W-band Spectrometer Array
Matthew Sieth, Sarah Church, Judy M. Lau, Patricia Voll (Stanford University), Todd Gaier, Pekka Kangaslahti, Lorene Samoska, Mary Soria (Jet Propulsion Laboratory, California Institute of Technology), Kieran Cleary, Anthony C. S. Readhead, Rodrigo Reeves (California Institute of Technology), Andrew Harris (University of Maryland), Jeffrey Neilson, Sami Tantawi, Dan Van Winkle (SLAC National Accelerator Laboratory)
We are developing an 8-pixel spectrometer that could be deployed at the Green Bank Telescope. The instrument is designed to map gas-tracing spectral lines in the 85--100 GHz band including HCN, HCO+, CS, and their rarer isotopomers. These maps will be utilized for exploring the physics of star formation in dense molecular clouds in nearby galaxies such as M33 as well as in the Galaxy. The receiver components for each pixel are integrated into miniature MMIC (Monolithic Microwave Integrated Circuit) amplifier-based multichip modules and multilayer PCBs route signals to and from the modules. The array is designed to be mass-producible and compact so that it would be straightforward to scale to hundreds of pixels for a future instrument.
Advanced Multibeam Spectrometer for the Green Bank Telescope
Anish Roshi (NRAO), Marty Bloss (NRAO), Patrick Brandt (NRAO), Srikanth Bussa (NRAO, U. Akron), Hong Chen (U.C., Berkeley), Paul Demorest (NRAO), Gregory Desvignes (U.C., Berkeley), Terry Filiba (U.C., Berkeley), Richard J. Fisher (NRAO), John Ford (NRAO), David Frayer (NRAO), Robert Garwood (NRAO), Suraj Gowda (U.C., Berkeley), Glenn Jones (NRAO, Caltech), Billy Mallard (U.C., Berkeley), Joseph Masters (NRAO), Randy McCullough (NRAO), Guifre Molera (U.C., Berkeley), Karen O'Neil (NRAO), Jason Ray (NRAO), Simon Scott (U.C., Berkeley), Amy Shelton (NRAO), Andrew Siemion (U.C., Berkeley), Mark Wagner (U.C., Berkeley), Galen Watts (NRAO), Dan Werthimer (U.C., Berkeley), Mark Whitehead (NRAO)
The National Science Foundation Advanced Technologies and Instrumentation (NSF-ATI) program is funding a new spectrometer backend for the Green Bank Telescope (GBT). This spectrometer is being built by the CICADA collaboration---a collaboration between the National Radio Astronomy Observatory (NRAO) and the Center for Astronomy Signal Processing and Electronics Research (CASPER) at the University of California, Berkeley.
The new backend will replace capabilities of the existing spectrometers and will support data processing from focal plane array systems. The spectrometer will be capable of processing up to 1.25 GHz bandwidth from 8 dual polarized beams or a bandwidth up to 10 GHz from a dual polarized beam. The spectrometer will be using 8 bit analog to digital converters (ADC), which give better dynamic range than existing GBT spectrometers. There will be 8 tunable digital sub-bands within the 1.25 GHz bandwidth, which will enhance the capability of simultaneous observation of multiple spectral transitions. The maximum spectral dump rate to disk will be about 0.5 ms. The vastly enhanced backend capabilities will support several new science projects with the GBT. These projects include mapping temperature and density structure of molecular clouds; searches for organic molecules in the interstellar medium; determination of the fundamental constants of our evolving Universe; redshifted spectral features from galaxies across cosmic time and survey for pulsars in the extreme gravitational environment of the Galactic Center.
Direct Measurement of the Expansion of Galactic UCHII regions
D. Anish Roshi & Dana S. Balser (NRAO)
Massive stars (> 10 Msun) are fundamental to the evolution of galaxies, but their formation and early evolution are not well understood. During the early stages of massive star formation significant amounts of UV radiation is produced, ionizing surrounding material and giving rise to ultra-compact H II regions (UCHII regions). These UCHII regions have lifetimes (few × 105 yr) significantly larger than their expansion time scale (few × 103 yr). This discrepancy has been called the "UCHII region lifetime problem." We have developed a new method to directly measure the expansion of UCHII regions and thus resolve the lifetime problem. The method utilizes measurement of carbon recombination line (CRL) emission from photo-dissociation regions (PDRs) in the vicinity of the UCHII regions. Models of these regions suggest that it is possible to detect emission from PDR material in the front and back of the UCHII region at frequencies > 20 GHz. The velocity difference between the line emission from these two components provides a direct measure of the UCHII region expansion. We have used the Green Bank Telescope (GBT) to observe CRL emission at 33 GHz toward 8 UCHII regions. Double line profiles are detected only toward 2 sources. We discuss the implication of these measurements and possible resolutions to the lifetime problem.
The Context of Star Formation
Karen O'Neil (NRAO), David Frayer (NRAO)
Stars form on the scale of a solar system, but their formation can be triggered by events on much larger scales, up to the size of a galaxy, such as density waves, tidal encounters, AGN activity, feedback from previous star formation, cloud collisions, and so on. Advances in our understanding of star formation will require observations on all angular scales. This includes understanding the star formation rates and processes in both our own and other galaxies to determine the overall formation and evolution of all stellar systems. The dense gas traces of HCN, HCO+, and HNC are key in studying the material associated with the ongoing star-formation and AGN activity. The amount dense gas traced by HCN compared to the total gas mass is a proxy for the star-formation efficiency. The nuclear regions of galaxies and ultraluminous infrared galaxies show enhanced star-formation efficiencies and much higher HCN/CO ratios in comparison to the disks of spiral galaxies. Looking at the other extreme, the molecular gas content in the low surface density regimes in the outer reaches of galaxies and in low surface brightness galaxies also provide valuable insight into star formation processes, and only a theory which can explain all ends of the density spectra can truly be considered complete.
From Comets to Clusters: The Next Decade with the Green Bank Telescope
Karen O'Neil, D. Balser, D. Frayer, F. Ghigo, T. Hunter, G. Langston, J. Lockman, R. Maddalena, B. Mason, T. Minter, R. Prestage, P. Ries, S. Ransom, A. Roshi (NRAO)
The Robert C. Byrd Green Bank Telescope, or GBT, is the world's premiere single-dish radio telescope operating at centimeter-millimeter wavelengths. The enormous collecting area, unblocked aperture, and excellent surface provide unprecedented sensitivity across the telescope's full 0.1 - 100 GHz range, a larger frequency coverage than any other telescope. As the telescope is fully steerable, 85% of the celestial sphere is accessible to the GBT. In partnership with the astronomical community, the GBT enables transformational science across a wide range of research areas. Over the next decade a number of instrumentation upgrades are planned for the GBT which will enable it to remain at the forefront of astronomy while providing key insights into many of the questions of concern to the astronomical community.
Deep Neutral Hydrogen Surveys with the Arecibo 305-m Telescope
Robert Minchin (NAIC Arecibo Observatory)
Neutral hydrogen surveys provide the potential to investigate how cosmic structures form and evolve, and how baryons cycle in and out of galaxies. Using the Arecibo L-band Feed Array (ALFA), the Arecibo Galaxy Environment Survey (AGES) and the ALFA Zone of Avoidance Survey (ALFA-ZOA) are two deep surveys, reaching noise levels (with a 10 km/s velocity resolution) of better than 1 mJy/beam/channel. AGES is targeting structures in the nearby universe, covering the full gamut from the Local Void to the Virgo Cluster while ALFA-ZOA is surveying the sky behind our galaxy. This extends what New Worlds, New Horizons called the "precision map of the cosmic cartography of the present-day local universe" to this unmapped region of space. I will describe the results of these surveys to date and what we expect to learn as they advance towards completion. I will also give an overview of the expected capabilities of the proposed AO40 phased-array feed for Arecibo and some of its potential uses for neutral hydrogen surveys.
Cosmic Microwave Background Polarimetry with Feedhorns: Coupled Superconducting Polarimeters
Johannes Hubmayr (NIST); TRUCE collaboration
Cosmic microwave background polarimetry provides a means to detect signals from the inflationary epoch, study fundamental physics at 1016 GeV energy scales, constrain dark energy and measure the sum of the neutrino masses. These science deliverables address three out of the four inquiry themes of the 2010 Decadal Survey of Astronomy & and Astrophysics: "Discovery," "Origins," and "Frontiers of Knowledge." Probing these themes requires instruments with ever increasing focal plane sensitivity together with low systematic error levels. To this end, we are developing scalable, all silicon focal planes that consist of micro-machined, silicon platelet feedhorn arrays coupled to arrays of superconducting polarimeters. We describe this focal plane architecture and present recent laboratory measurements of a 6-cm, 84 feed array. Single pixel polarimeters are currently being fielded in the Atacama B-mode Search (ABS). Monolithic polarimeter arrays with micro-machined silicon feedhorns are scheduled for deployment in both the South Pole Telescope Polarimeter (SPTpol) and the Atacama Cosmology Telescope Polarimeter (ACTpol) in 2012.
A Confusion-Limited Millimeter/Submillimeter Survey of the Giant Molecular Cloud Sgr B2(N)
DeWayne T. Halfen (Arizona)
Understanding the physical and chemical properties of giant molecular clouds is fundamental in evaluating the formation of solar systems and planets. Another important aspect is the connection between the organic content of such clouds and solar system bodies, including meteorites that can deliver prebiotic material to planet surfaces, a possible step in the origin of life. One of the most massive and chemically complex giant molecular clouds in the Galaxy is Sgr B2(N), found in the Galactic center. Of the over 145 chemical species detected in interstellar gas, approximately half have been discovered in Sgr B2(N), which contains many complex organic molecules. These species are typically asymmetric tops often with internal rotation and/or inversion, which can cause their rotational spectra to be quite complicated. Therefore, a wide range of favorable transitions over a sufficiently large frequency range must be observed to reliably confirm the presence of individual species in this source. For that reason, we have conducted a continuous spectral-line survey of Sgr B2(N) at the confusion limit using the Arizona Radio Observatory (ARO) 12-m telescope on Kitt Peak and Submillimeter Telescope (SMT) on Mt. Graham. The survey covers the 1, 2, and 3 mm atmospheric windows in the range 65--280 GHz. Over 10,000 lines have been observed in this survey. The high density of spectral lines means that chance coincidences with other interstellar features are extremely likely. The purpose of this study is to accurately establish the presence and relative abundances of the organic compounds in this molecular cloud, determine the degree of chemical complexity, and compare such results with molecular content of carbonaceous chondrites. The observations are almost complete and an analysis is underway. The data and preliminary results will be presented.
MMIC Array Technology for CMB Polarization
Todd Gaier (JPL/Caltech)
MMIC technology has enabled highly integrated cryogenic receivers operating between 20 and 200 GHz. The technology naturally lends itself to array techniques including focal plane imaging arrays, interferometric arrays and spectroscopic imagers. The first of these large arrays for CMB polarization, QUIET, recently completed observations in Chile. The array sensitivity approached 50 µK-\sqrt{s} at both 40 and 90 GHz. In preparation for larger arrays such as QUIET Phase II, significant work has been carried out to further improve the array performance. Improvements have been made in device technologies, module design, and component performance. These developments will be discussed along with future plans for array receivers.
Physical and Chemical Properties of the Envelopes of Supermassive Stars
Jessica Dodd (University of Arizona), Lucy Ziurys (University of Arizona), Nick Woolf (University of Arizona)
Supermassive stars such as VY Canis Majoris (VY CMa) undergo substantial mass loss during the late stages of evolution. The circumstellar enevelopes that form as a result of this mass loss can provide important clues about the final fate of these objects. In order to further our understanding of such stars, millimeter-wave molecular line observations of supergiant envelopes are being conducted using the telescopes of the Arizona Radio Observatory (ARO). A 1 mm molecular line survey of VY CMa has already been conducted. This study showed that the envelope of this star has a complex velocity structure in dense, molecular material, resulting from apparently random mass loss events. This object was also found to have greater chemical complexity than previously thought existed for oxygen-rich supergiants, based on usual oxise and hydroxide species. A similar survey at 1 mm using the ARO Sub-millimeter Telescope is currently being conducted for another supermassive star, NML Cygnus. The envelope of this supergiant appears to be as chemically rich in molecular content, but is less complicated kinematically than that of VY CMa. Current results of these observations will be presented.
The LABOCA/ACT Survey of Clusters at All Redshifts
Andrew Baker
Exploiting the Sunyaev-Zel'dovich (SZ) effect, the Atacama Cosmology Telescope (ACT) has selected new samples of massive galaxy clusters out to z ~ 1, many of which had not been previously known. Multiwavelength followup of these clusters includes 870 µm mappping with the LABOCA camera on the APEX telescope, which allows higher-resolution imaging of the clusters' SZ increments and detection of gravitationally lensed submillimeter galaxies ideal for detailed study with ALMA. This work prefigures surveys that will be done with CCAT and addresses two of the key science questions from the Astro2010 report: How do cosmic structures form and evolve, and how do baryons cycle in and out of galaxies (and what do they do while they are there)?
The View from the NSFJ
Jim Ulvestad
The recommended ground-based program from "New Worlds, New Horizons" (NWNH) assumed a budget whose purchasing power increases by 4 percent per year over the decade. However, the most recent budget requests, and the large uncertainties in the U.S. federal budget, appear to make it unlikely that this rate of increase will be achieved for NSF-funded astronomy. If the budget is closer to being flat in purchasing power, the NWNH report states (page 188) that "the only way there can be any significant new initiative is through very large reductions in the funding for existing facilities and budget lines." In this talk, I will review the FY 2012 budget request, show the impact of different future budget scenarios, and examine the consequences for existing facilities and the NWNH initiatives.
Testing Fundamental Physics with Cosmic Microwave Background Polarization and other RMS Measurements in the Next Decade
Sarah Church
In past decade we learned a great deal about the origin and contents of the universe. The so-called "standard cosmological model" which describes a universe that began with an inflationary epoch and that is today dominated by dark energy and dark matter has passed a range of observational tests. Widely different techniques including radio and millimeter wavelength measurements of anisotropies in the Cosmic Microwave Background radiation, optical and infrared measurements of supernovae and gravitational lensing, and X-ray and optical measurements of galaxy clusters display remarkable agreement on the proportions of dark matter and dark energy in the universe. However, fundamental mysteries remain. What is the physics underlying inflation and dark energy? What are the properties of the particles that constitute dark matter, and what is the mass of the neutrino? The quest for the answers in the next decade requires new instruments is likely to involve close cooperation between the particle physics and astrophysics communities. I will discuss the particular example of measurements of CMB polarization to probe the details of the inflaton potential, the neutrino mass and more speculative areas of inflation physics, and I will touch upon the relationship of RMS observations to other large experiments that will probe the details of dark energy and dark matter.
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