The Morphology of Dust-Obscured Starbursts: the e-MERLIN SuperCLASS Legacy Survey

University Of Texas At Austin, Austin TX

Investigators

Abstract

Galaxies -- collections of hundreds of billions of stars all bound by gravity -- are a fundamental building block in the evolution of our Universe. Our own Milky Way galaxy is regarded as 'normal' in the Universe today, stretching 100,000 light years across and forming stars at a rate of 1-2 new suns per year. But, as we look farther out into the Universe, it seems that galaxies in the distant past (10 billion years ago) were dramatically different. Extreme "starbursting" galaxies that produced 100 to 2,000 stars per year were much more typical, and most stars formed at that time came from such starbursts. The awarded team is trying to determine why these galaxies were so important in the Universe's history and why they are so extreme, for example whether or not they are caused by the catastrophic collision of two smaller galaxies, or whether the gas (the fuel needed to power star formation) was more dense and efficient when the Universe was much younger. These extreme starbursts are also heavily obscured by dust, making them hard to see in optical light visible to our eyes. Cutting edge radio-wavelength data from the e-MERLIN telescope will be used to peer through the dust and determine the powering mechanism for the Universe's most extreme starbursting galaxies. This project will support the retention of under-represented students in astrophysics research through participation in the TAURUS program at UT Austin, where undergraduate students spend nine weeks of the summer on a research project. The awardee will be proactive in engaging and supporting under-represented students in communities like TAURUS. With a unique data set of high-resolution (0."1) deep (4 uJy) radio 1.4 GHz continuum data from e-MERLIN covering 1.77 deg^2 in the SuperCLASS field, the awardees will assess the evolutionary origins of highly-obscured radio galaxies in a statistically large sample (few x 100) out to z~3. The objectives are to answer the following questions: (1) Are the high-SFRs in dusty starbursts primarily driven by galaxy interactions or not? (2) Does feedback from Active Galactic Nuclei (AGN) in obscured starbursts play a role in suppressing star-formation? Or is there no discernible difference in star formation seen in starbursts with or without radio-luminous AGN (and what is the dependence on the AGN luminosity)? (3) What do galaxies' star-formation surface densities tell us about the intensity of star formation and relative obscuration geometries (when compared to optical imaging)? (4) Can one learn about the physical origins of the mysterious far-infrared/radio correlation by analyzing galaxies' radio synchrotron slope and radio morphologies? Answering these questions through direct morphological analysis of the e-MERLIN SuperCLASS data products will have significant impact on galaxy evolution studies.