abstract

• 98 post-merger galaxies(47 archival,51 new observation)

• control sample: xGASS (same stellar mass range,observing strategy, detection threshold, data analysis procedure)

• result:
  (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.
  (3) The median atomic gas fraction enhancement (∆f_gas), computed on a galaxy-by-galaxy basis at fixed stellar mass, is 0.51 dex.

• demonstration:
  (1) Recently merged galaxies are typically a factor of ~ 3 more HI rich than control galaxies of the same M_*.
  (2) Enhanced atomic gas fractions in post-mergers are not purely a reflection of changes in star formation activity.

• conclusion
  Merger-induced starbursts and outflows do not lead to prompt quenching via exhaustion/expulsion of the galactic gas reservoirs. 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.

Survey strategy and sample selection

follow the procedures of the xGASS survey.

sources of post-mergers

• Galaxy Zoo,100
• based on the visual classifications of Nair & Abraham 113(removed the duplicates)
  redshift and declination cut: z<0.04, 0<δ<37 degree(213 to 37)
• asymmetry-selected (r-band asymmetries > 0.05,from Simard;same declination and redshift cut) 114

further cut

• check SDSS image for companions within 1 arcmin to avoid contamination
• logM_*>9M
• 10<α<17 hours(Arecibo observing limit and our observing time allocation)(remove 9)
  archival observation exists for 47