GeminiFocus October 2018 - Page 8

they correspond to ultraluminous infrared galaxies (ULIRGs). In the local Universe, the far-infrared emission from ULIRGs is typically powered by starbursts and AGN. To obtain redshift estimates, and to disentangle the contribution of these two power sources, we used multiwavelength data from surveys in the optical and infrared, as well as new ra- dio continuum data from the Australia Tele- scope Compact Array and Very Large Array. The ULIRGs we identify consist of a combi- nation of pure starburst galaxies and com- posite AGN/starburst objects. We find that the ULIRGS with strong AGN tend to reside in hosts with smaller scale sizes than purely star-forming galaxies of similar infrared lu- minosity. Like their local counterparts, the ULIRGs in this study seem to show signs of recent merger activity, such as highly disturbed morphologies. We also find a candidate tri- ple AGN system (Figure 3), which consists of three AGN with photometric redshifts of z = 1.4 (spectroscopic redshifts are required to confirm the triple AGN system): one is a radio-loud AGN, suggesting the presence of radio jets and lobes; one is a Type-2 AGN, showing both narrow and broadened op- tical spectral emission lines; and one is a Type-1 AGN, showing narrow emission lines only (though still wider than emission lines in normal galaxies). Both the Type-1 and Type-2 AGN have strong mid-infrared emis- sion that identifies them as probable AGN. This system was not identified as multiple in the standard photometry products from the VIDEO or SERVS surveys, raising the possibil- ity that many more such systems may exist unrecognized in current surveys. In the future, we believe that observations of extragalactic fields with MCAO will fulfill a valuable role supplementing deeper, but more resource intensive, observations with space-based platforms such as the James Webb Space Telescope (JWST) (Kalirai, 2018). 6 GeminiFocus For example, surveys of high-redshift ULIRGs with ground-based MCAO could be used to pick interesting individual targets for JWST. References: Jarvis, M. J., Bonfield, D. G., Bruce, V. A.,  et al., Monthly Notices of the Royal Astronomical Soci- ety, 428: 1281, 2013 Kalirai, J., Contemporary Physics, 59: 251, 2018 Lacy, M., Nyland, K., Mao, M., et al., The Astro- physical Journal, 864: 8, 2018 Lonsdale, C., Smith H. E., Rowan-Robinson, M., et al., Publications of the Astronomical Society of the Pacific, 115: 897, 2003 Mauduit, J.-C., Lacy, M., Farrah, D.,  et al., Publi- cations of the Astronomical Society of the Pacif- ic, 124: 1135, 2012 Rigaut, F., Neichel, B., Boccas, M., et al., Month- ly Notices of the Royal Astronomical Soci- ety, 437: 2361, 2014 Neichel, B., Rigaut, F., Vidal, F.,  et al., Month- ly Notices of the Royal Astronomical Soci- ety, 440: 1002, 2014 van der Wel, A., Franx, M., van Dokkum, P. G., et al., The Astrophysical Journal, 788: 28, 2014 Mark Lacy is a Staff Scientist at the National Radio Astronomy Observatory. He can be reached at: [email protected] Kristina Nyland is a Research Associate at the Na- tional Radio Astronomy Observatory. She can be reached at: [email protected] Susan Ridgway is an Associate Scientist at the Na- tional Optical Astronomy Observatory. She can be reached at: [email protected] October 2018