2022MNRAS.516.2947S -
Mon. Not. R. Astron. Soc., 516, 2947-2970 (2022/October-3)
FLASH pilot survey: detections of associated 21 cm H I absorption in GAMA galaxies at 0.42 < z < 1.00.
SU R., SADLER E.M., ALLISON J.R., MAHONY E.K., MOSS V.A., WHITING M.T., YOON H., ADITYA J.N.H.S., BELLSTEDT S., ROBOTHAM A.S.G., GARRATT-SMITHSON L., GU M., KORIBALSKI B.S., SORIA R. and WENG S.
Abstract (from CDS):
We present the results of a search for associated 21 cm H I absorption at redshift 0.42 < z < 1.00 in radio-loud galaxies from three Galaxy And Mass Assembly (GAMA) survey fields. These observations were carried out as part of a pilot survey for the Australian SKA Pathfinder (ASKAP) First Large Absorption Survey in H I (FLASH). From a sample of 326 radio sources with 855.5 MHz peak flux density above 10 mJy, we detected two associated H I absorption systems, in SDSS J090331+010847 at z = 0.522 and SDSS J113622+004852 at z = 0.563. Both galaxies are massive (stellar mass $\gt 10^{11}\, \mathrm{M}_\odot$) and have optical spectra characteristic of luminous red galaxies, though spectral energy distribution fitting implies that SDSS J113622+004852 contains a dust-obscured starburst with star formation rate ∼69 M⊙ yr–1. The H I absorption lines have a high optical depth, with τpk of 1.77 ± 0.16 for SDSS J090331+010847 (the highest value for any z > 0.1 associated system found to date) and 0.14 ± 0.01 for SDSS J113622+004852. In the redshift range probed by our ASKAP observations, the detection rate for associated H I absorption lines (with τpk > 0.1 and at least 3σ significance) is $2.9_{-2.6}^{+9.7}$ per cent. Although the current sample is small, this rate is consistent with a trend seen in other studies for a lower detection rate of associated 21 cm H I absorption systems at higher redshift. We also searched for OH absorption lines at 0.67 < z < 1.34, but no detection was made in the 145 radio sources searched.
Abstract Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
methods: observational - galaxies: active - galaxies: ISM - galaxies: nuclei - radio lines: ISM
VizieR on-line data:
<Available at CDS (J/MNRAS/516/2947): table4.dat table5.dat tablea1.dat>
Simbad objects:
330
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