2019A&A...627A.107L


Query : 2019A&A...627A.107L

2019A&A...627A.107L - Astronomy and Astrophysics, volume 627A, 107-107 (2019/7-1)

CO observations of major merger pairs at z = 0: molecular gas mass and star formation.

LISENFELD U., XU C.K., GAO Y., DOMINGUE D.L., CAO C., YUN M.S. and ZUO P.

Abstract (from CDS):

We present CO observations of 78 spiral galaxies in local merger pairs. These galaxies represent a subsample of a Ks-band-selected sample consisting of 88 close major-merger pairs (HKPAIRs), 44 spiral-spiral (S+S) pairs, and 44 spiral-elliptical (S+E) pairs, with separation <20h–1kpc and mass ratio <2.5. For all objects, the star formation rate (SFR) and dust mass were derived from Herschel PACS and SPIRE data, and the atomic gas mass, MHI, from the Green Bank Telescope HI observations. The complete data set allows us to study the relation between gas (atomic and molecular) mass, dust mass, and SFR in merger galaxies. We derive the molecular gas fraction (MH2/M*), molecular-to-atomic gas mass ratio (MH2/MHI), gas-to-dust mass ratio and SFE (= SFR/MH2) and study their dependences on pair type (S+S compared to S+E), stellar mass, and the presence of morphological interaction signs. We find an overall moderate enhancement (∼2x) in both molecular gas fraction (MH2/M*) and molecular-to-atomic gas ratio (MH2/MHI) for star-forming galaxies in major-merger pairs compared to non-interacting comparison samples, whereas no enhancement was found for the SFE nor for the total gas mass fraction ((MHI+MH2)/M*). When divided into S+S and S+E, low mass and high mass, and with and without interaction signs, there is a small difference in SFE, a moderate difference in MH2/M*, and a strong difference in MH2/MHI between subsamples. For the molecular-to-atomic gas ratio MH2/MHI, the difference between S+S and S+E subsamples is 0.55±0.18dex and between pairs with and without interaction sign 0.65±0.16dex. Together, our results suggest that (1) star formation enhancement in close major-merger pairs occurs mainly in S+S pairs after the first close encounter (indicated by interaction signs) because the HI gas is compressed into star-forming molecular gas by the tidal torque; and (2) this effect is much weakened in the S+E pairs.

Abstract Copyright: © ESO 2019

Journal keyword(s): galaxies: evolution - galaxies: general - galaxies: interactions - galaxies: starburst - ISM: molecules

VizieR on-line data: <Available at CDS (J/A+A/627/A107): table1.dat table2.dat listco10.dat spco10.fits listco21.dat spco21.fits>

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 KPAIR J0020+0049 PaG 00 20 26.6 +00 49 48           ~ 4 0
2 MCG+00-04-074 EmG 01 18 34.1439907008 -00 13 41.783267388   15.5       ~ 20 1
3 MCG+00-04-075 H2G 01 18 35.603 -00 13 59.13   16.5       ~ 12 1
4 KPAIR J0211-0039 PaG 02 11 07.36 -00 39 18.2           ~ 6 0
5 KPAIR J0338+0109 PaG 03 38 12.6 +01 09 55           ~ 3 0
6 KPAIR J1211+4039 PaG 12 11 55.8 +40 39 18           ~ 2 0
7 UGC 8327 PaG 13 15 15.73 +44 24 27.0           ~ 16 0
8 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2838 4

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2022.08.18-01:49:49

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