Projects per year
Abstract
We present a detailed assessment of the global atomic hydrogen gas fraction (fgas = log[MHI/M*]) in a sample of post-merger galaxies identified in the Sloan Digital Sky Survey (SDSS). Archival HI measurements of 47 targets are combined with new Arecibo observations of a further 51 galaxies. The stellar mass range of the post-merger sample, our observing strategy, detection thresholds and data analysis procedures replicate those of the extended GALEX Arecibo SDSS Survey (xGASS) which can therefore be used as a control sample. Our principal results are (1) the post-merger sample shows a ~50 per cent higher HI detection fraction compared with xGASS; (2) accounting for non-detections, the median atomic gas fraction of the post-merger sample is larger than the control sample by 0.3-0.6 dex; and (3) the median atomic gas fraction enhancement (Δfgas), computed on a galaxy-by-galaxy basis at fixed stellar mass, is 0.51 dex. Our results demonstrate that recently merged galaxies are typically a factor of ~3 more HI rich than control galaxies of the same M*. If the control sample is additionally matched in star formation rate, the median HI excess is reduced to Δfgas = 0.2 dex, showing that the enhanced atomic gas fractions in post-mergers are not purely a reflection of changes in star formation activity. We conclude that merger-induced starbursts and outflows do not lead to prompt quenching via exhaustion/expulsion of the galactic gas reservoirs. Instead, we propose that if star formation ceases after a merger, it is more likely due to an enhanced turbulence which renders the galaxy unable to effectively form new stars.
Original language | English |
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Pages (from-to) | 3447-3466 |
Number of pages | 20 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 478 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1 Aug 2018 |
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ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions
Kewley, L., Wyithe, S., Sadler, E., Staveley-Smith, L., Glazebrook, K., Jackson, C., Bland-Hawthorn, J., Asplund, M., Power, C. & Driver, S.
1/01/17 → 31/12/23
Project: Research
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Using Australia's Next-generation Radio Telescopes to Unveil the Gas Cycle in Galaxies
1/01/15 → 31/12/17
Project: Research