J/MNRAS/478/3447 SDSS post-merger galaxies HI data (Ellison+, 2018)
Enhanced atomic gas fractions in recently merged galaxies:
quenching is not a result of post-merger gas exhaustion.
Ellison S.L., Catinella B., Cortese L.
<Mon. Not. R. Astron. Soc., 478, 3447-3466 (2018)>
=2018MNRAS.478.3447E 2018MNRAS.478.3447E (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; H I data
Keywords: galaxies: interactions - galaxies: ISM - galaxies: peculiar
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 0.3-0.6dex; and (3) the
median atomic gas fraction enhancement (Δfgas), computed on a
galaxy-by-galaxy basis at fixed stellar mass, is 0.51dex. 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 H I
excess is reduced to Δfgas=0.2dex, 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.
Description:
We have compiled a sample of 107 visually classified post-merger
galaxies within a fixed right ascension and declination footprint
(10<RA<17h, 0<DE<37deg) with z<0.04 and logM*>9.0M☉.
Forty-seven of these post-mergers have existing measurements of MHI in
the literature. Arecibo observations of 51 of the remaining 60
post-mergers have been completed with an observing strategy identical
to the xGASS sample of ∼1200 representative galaxies from the SDSS
with logM*>9.0 (Catinella et al., 2018, Cat. J/MNRAS/476/875).
The Arecibo observations were carried out in six sessions, between
2017 January and April, with 32h allocated under program A3117 (PI
Ellison).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 51 Arecibo observations of post-mergers,
ordered by SDSS objID
table2.dat 94 107 Sample properties and atomic gas fractions of
the final post-merger sample,
ordered by SDSS objID
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See also:
VIII/77 : HI spectral properties of galaxies (Springob+, 2005)
J/AJ/142/170 : ALFALFA survey: the α.40 HI source catalog
(Haynes+, 2011)
J/MNRAS/476/875 : xGASS catalog (Catinella+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 I18 --- objID SDSS DR7 objID
20- 28 F9.5 deg RAdeg Right ascension (J2000)
30- 37 F8.5 deg DEdeg Declination (J2000)
39- 46 F8.6 --- zHI ?=- HI redshift
48- 49 I2 min Ton On-source integration time of the Arecibo
observation
51- 55 F5.1 km/s W50 ?=- Observed velocity width of the source
line profile, measured at the 50% level
of each peak
57- 60 F4.2 Jy.km/s Sobs ?=- Observed HI flux
62- 65 F4.2 Jy.km/s e_Sobs ?=- Observed HI flux error
67- 70 F4.2 mJy rms rms noise of the observation
72- 75 F4.1 --- S/N ?=- Signal-to-noise ratio
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 I18 --- objID SDSS DR7 objID
20- 28 F9.5 deg RAdeg Right ascension (J2000)
30- 37 F8.5 deg DEdeg Declination (J2000)
39- 44 F6.4 --- zSDSS SDSS redshift
46- 50 F5.2 [Msun] logM* Stellar mass
52 A1 --- l_logMHI Limit flag on logMHI
53- 57 F5.2 [Msun] logMHI ?=- HI mass
59 A1 --- l_logfgas Limit flag on logfgas
60- 64 F5.2 [-] logfgas ?=- Global atomic hydrogen gas fraction
(log[MHI/M*])
66 A1 --- l_Dfgas Limit flag on Dfgas
67- 71 F5.2 --- Dfgas ?=- Median atomic gas fraction enhancement,
{DELTA}fgas (1)
73- 94 A22 --- Ref HI reference (2)
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Note (1): Dfgas calculations include non-detections and are computed for
galaxies with log M*≤10.8M☉.
Note (2): HI references as follows:
ALFALFA = Haynes et al., 2011, Cat. J/AJ/142/170 and α70 data
release, http://egg.astro.cornell.edu/alfalfa/data/index.php
xGASS = Catinella et al., 2018, Cat. J/MNRAS/476/875
This work = This work
Ellison et al. (2015) = Ellison et al., 2015MNRAS.448..221E 2015MNRAS.448..221E
Springob et al. (2005) = Springob et al., 2005ApJS..160..149S 2005ApJS..160..149S, Cat. VIII/77
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Aug-2021