Details

Autor(en) / Beteiligte

• Su, Renzhi
• Sadler, Elaine M
• Allison, James R
• Mahony, Elizabeth K
• Moss, Vanessa A
• Whiting, Matthew T
• Yoon, Hyein
• Aditya, J N H S
• Bellstedt, Sabine
• Robotham, Aaron S G
• Garratt-Smithson, Lilian
• Gu, Minfeng
• Koribalski, Bärbel S
• Soria, Roberto
• Weng, Simon

Titel

FLASH pilot survey: detections of associated 21 cm H i absorption in GAMA galaxies at 0.42 < z < 1.00

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2022-09, Vol.516 (2), p.2947-2970

Ort / Verlag

United Kingdom: Oxford University Press

Erscheinungsjahr

2022

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• ABSTRACT 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.