Colloq Abstract - Johnson

July 25

4pm Mountain

 

Megan Johnson

CSIRO

 

Evolution of Dwarf Irregular Galaxies

Abstract

In this talk, I present two projects that reflect my current areas of dwarf galaxy research.  The first part of my talk presents the recent work on a dwarf irregular galaxy called ESO 324-G024, which resides in the Centaurus A (Cen A) Galaxy Group. It is at nearly the same distance as NGC 5128, which is the S0 host galaxy of the radio source, Cen A. ESO 324-G024 has a striking HI morphology with a long, ~2.5 kpc extension that stretches away from the center of NGC 5128 and lies in projection against the northern radio lobe of Cen A.  Because of its proximity and HI morphology, ESO 324-G024 appears to reside *inside* the northern radio lobe of Cen A.  However, we see no signs of depolarization in 20 cm or 6 cm radio continuum observations of Cen A at the location of ESO 324-G024 and conclude that it is most likely behind the northern radio lobe.  In addition, we determine that ram pressure is the most probable mechanism responsible for creating the HI tail in ESO 324-G024.  If situations such as this are common to all radio galaxies, then ESO 324-G024 may offer insights into galaxy assembly and growth and provide a glimpse of what may be possible with the VLA Sky Survey project.

            The second part of my talk focuses on a survey aimed at understanding the radio continuum -- far-infrared correlation in low mass galaxies and is called Continuum Halos In Local LVHIS Irregular Nearby Galaxies (CHILLING).  The CHILLING project uses the Australia Telescope Compact Array (ATCA) to map a sample of 15 dwarf irregular and blue compact dwarf galaxies at two frequency bands, the 16 cm band and the 3/6 cm band, in order to study the radio continuum and polarization properties of each target.  We observe each object in three array configurations at each frequency in order to probe a variety of spatial scales.  In this way, we plan to connect star formation regions, as identified by ancillary data, to any continuum emission regions detected.  The wide bandwidth capabilities of the ATCA make observations of faint, low surface brightness dwarf galaxies possible and expanding this project to the northern hemisphere with the JVLA would provide a statistically significant sample of continuum and polarization studies of dwarfs for the first time.

 

 

 

 

 

 

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