A subarcsecond near-infrared view of massive galaxies at z > 1 with Gemini Multiconjugate Adaptive Optics

Astrophysical Journal Institute of Physics 864:1 (2018) 8

Authors:

M Lacy, K Nyland, M Mao, P Jagannathan, J Pforr, J Afonso, D Farrah, P Guarnieri, E Gonzales-Solares, Matthew J Jarvis, C Maraston, DM Nielsen, AO Petric, A Sajina, JA Surace, M Vaccari

Abstract:

We present images taken using the Gemini South Adaptive Optics Imager (GSAOI) with the Gemini Multiconjugate Adaptive Optics System (GeMS) in three 2 arcmin$^2$ fields in the Spitzer Extragalactic Representative Volume Survey. These GeMS/GSAOI observations are among the first $\approx 0.1^{''}$ resolution data in the near-infrared spanning extragalactic fields exceeding $1.5^{\prime}$ in size. We use these data to estimate galaxy sizes, obtaining results similar to those from studies with the Hubble Space Telescope, though we find a higher fraction of compact star forming galaxies at $z>2$. To disentangle the star-forming galaxies from active galactic nuclei (AGN), we use multiwavelength data from surveys in the optical and infrared, including far-infrared data from Herschel, as well as new radio continuum data from the Australia Telescope Compact Array and Very Large Array. We identify ultraluminous infrared galaxies (ULIRGs) at $z \sim 1-3$, which consist of a combination of pure starburst galaxies and Active Galactic Nuclei (AGN)/starburst composites. The ULIRGs show signs of recent merger activity, such as highly disturbed morphologies and include a rare candidate triple AGN. We find that AGN tend to reside in hosts with smaller scale sizes than purely star-forming galaxies of similar infrared luminosity. Our observations demonstrate the potential for MCAO to complement the deeper galaxy surveys to be made with the James Webb Space Telescope.

The origin of radio emission in broad absorption line quasars: Results from the LOFAR Two-metre Sky Survey

Astronomy and Astrophysics EDP Sciences 622 (2018) A15

Authors:

Leah Morabito, James Matthews, P Best, G Gurkan, Matthew Jarvis, I Prandoni, K Duncan, M Hardcastle, M Kunert-Bajraszewska, A Mechev, S Mooney, J Sabeter, H Rottgering, T Shimwell, D Smith, C Tasse, W Williams

Abstract:

We present a study of the low-frequency radio properties of broad absorption line quasars (BALQSOs) from the LOFAR Two-metre Sky-Survey Data Release 1 (LDR1). The value-added LDR1 catalogue contains Pan-STARRS counterparts, which we match with the Sloan Digital Sky Survey (SDSS) DR7 and DR12 quasar catalogues. We find that BALQSOs are twice as likely to be detected at 144 MHz than their non-BAL counterparts, and BALQSOs with low-ionisation species present in their spectra are three times more likely to be detected than those with only high-ionisation species. The BALQSO fraction at 144 MHz is constant with increasing radio luminosity, which is inconsistent with previous results at 1.4 GHz, indicating that observations at the different frequencies may be tracing different sources of radio emission. We cross-match radio sources between the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey and LDR1, which provides a bridge via the LDR1 Pan-STARRS counterparts to identify BALQSOs in SDSS. Consequently we expand the sample of BALQSOs detected in FIRST by a factor of three. The LDR1-detected BALQSOs in our sample are almost exclusively radio-quiet (log(R144 MHz) <2), with radio sizes at 144 MHz typically less than 200 kpc; these radio sizes tend to be larger than those at 1.4 GHz, suggesting more extended radio emission at low frequencies. We find that although the radio detection fraction increases with increasing balnicity index (BI), there is no correlation between BI and either low-frequency radio power or radio-loudness. This suggests that both radio emission and BI may be linked to the same underlying process, but are spatially distinct phenomena.

Identifying transient and variable sources in radio images

(2018)

Authors:

Antonia Rowlinson, Adam J Stewart, Jess W Broderick, John D Swinbank, Ralph AMJ Wijers, Dario Carbone, Yvette Cendes, Rob Fender, Alexander van der Horst, Gijs Molenaar, Bart Scheers, Tim Staley, Sean Farrell, Jean-Mathias Grießmeier, Martin Bell, Jochen Eislöffel, Casey J Law, Joeri van Leeuwen, Philippe Zarka

The far-infrared radio correlation at low radio frequency with LOFAR/H-ATLAS

Monthly Notices of the Royal Astronomical Society Oxford University Press 480:4 (2018) 5625-5644

Authors:

SC Read, DJB Smith, G Gürkan, MJ Hardcastle, WL Williams, PN Best, E Brinks, G Calistro-Rivera, KT Chyzy, K Duncan, L Dunne, Matthew Jarvis, Leah K Morabito, I Prandoni, HJA Röttgering, J Sabater, S Viaene

Abstract:

The radio and far-infrared luminosities of star-forming galaxies are tightly correlated over several orders of magnitude; this is known as the far-infrared radio correlation (FIRC). Previous studies have shown that a host of factors conspire to maintain a tight and linear FIRC, despite many models predicting deviation. This discrepancy between expectations and observations is concerning since a linear FIRC underpins the use of radio luminosity as a star-formation rate indicator. Using LOFAR 150MHz , FIRST 1.4GHz , and Herschel  infrared luminosities derived from the new LOFAR/H-ATLAS catalogue, we investigate possible variation in the monochromatic ( 250μm) FIRC at low and high radio frequencies. We use statistical techniques to probe the FIRC for an optically selected sample of 4082 emission-line classified star-forming galaxies as a function of redshift, effective dust temperature, stellar mass, specific star formation rate, and mid-infrared colour (an empirical proxy for specific star formation rate). Although the average FIRC at high radio frequency is consistent with expectations based on a standard power-law radio spectrum, the average correlation at 150MHz is not. We see evidence for redshift evolution of the FIRC at 150MHz⁠, and find that the FIRC varies with stellar mass, dust temperature, and specific star formation rate, whether the latter is probed using MAGPHYS fitting, or using mid-infrared colour as a proxy. We can explain the variation, to within 1σ, seen in the FIRC over mid-infrared colour by a combination of dust temperature, redshift, and stellar mass using a Bayesian partial correlation technique.

SPIRITS 16tn in NGC 3556: A Heavily Obscured and Low-luminosity Supernova at 8.8 Mpc

The Astrophysical Journal American Astronomical Society 863:1 (2018) 20

Authors:

Jacob E Jencson, Mansi M Kasliwal, Scott M Adams, Howard E Bond, Ryan M Lau, Joel Johansson, Assaf Horesh, Kunal P Mooley, Robert Fender, Kishalay De, Dónal O’Sullivan, Frank J Masci, Ann Marie Cody, Nadia Blagorodnova, Ori D Fox, Robert D Gehrz, Peter A Milne, Daniel A Perley, Nathan Smith, Schuyler D Van Dyk