J/ApJS/261/34 Bulge-disk decomposition of H-KPAIR sample (He+, 2022)
Close major-merger pairs at z=0: bulge-to-total ratio and star formation
enhancement.
He C., Xu C.K., Domingue D., Cao C., Huang J.-S.
<Astrophys. J. Suppl. Ser., 261, 34 (2022)>
=2022ApJS..261...34H 2022ApJS..261...34H
ADC_Keywords: Galaxies, IR; Models; Morphology; Photometry; Optical; Redshifts
Keywords: Galaxy evolution ; Galaxy interactions ; Galaxy structure ;
Star formation
Abstract:
We present a study of the bulge-to-total ratio (B/T) of a
Ks-band-selected sample of 88 close major-merger pairs of galaxies
(H-KPAIR), based on two-dimensional decompositions of SDSS r-band
images with GALFIT. We investigate the dependence of the
interaction-induced specific star formation rate enhancement
(sSFRenh) on the B/T ratio, and the effects of this dependence on
the differences between star-forming galaxies (SFGs) in spiral+spiral
(S+S) and spiral+elliptical (S+E) pairs. Of all the 132 spiral
galaxies in H-KPAIR, the 44 in S+E pairs show higher B/T than those in
the 44 S+S pairs, with means of B/T=0.35±0.05 and B/T=0.26±0.03,
respectively. There is a strong negative dependence of sSFRenh on the
B/T ratio, and only paired SFGs with B/T<0.3 show significant
(>5σ) enhancement. Paired SFGs in S+S pairs show a similar
trend, and many disky SFGs (B/T<0.1) in S+S pairs have strong sSFR
enhancements (sSFRenh>0.7dex). For SFGs in S+E pairs, the sSFR has
no clear B/T dependence, nor any significant enhancement in any B/T
bin. Disky SFGs in S+S pairs show significant (>4σ) enhancement
in molecular gas content (MH2/Mstar), while SFGs in S+E pairs have
no such enhancement in any B/T bin. No significant enhancement of the
total gas content (Mgas/Mstar) is found in any B/T bin for paired
galaxies. The star formation efficiency of either the total gas
(SFEgas=SFR/Mgas) or molecular gas (SFEH2=SFR/MH2) does not
depend on the B/T ratio. The only significant (>4σ) SFE
enhancement found for paired SFGs is the SFEgas for disky SFGs in S+S
pairs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 176 GALFIT results of 2MASX Ks-band-selected close
major-merger galaxy pair sample (H-KPAIR)
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/ApJS/142/1 : DEEP Groth Strip Survey. II. (Simard+, 2002)
J/ApJ/713/330 : Spitzer observations of major-merger galaxies (Xu+, 2010)
J/MNRAS/415/32 : COLD GASS survey (Saintonge+, 2011)
J/ApJS/196/11 : Bulge+disk decompositions of SDSS galaxies (Simard+, 2011)
J/MNRAS/446/3943 : galaxies 2D phot. decompositions in SDSS-DR7 (Meert+, 2015)
J/ApJS/222/16 : Major-merger pairs of z<0.1 gal. with Herschel (Cao+, 2016)
J/ApJ/829/78 : Dust properties of major-merger gal. pairs (Domingue+, 2016)
J/MNRAS/455/2440 : Gal. 2D phot. decompositions in r, g & i (Meert+, 2016)
J/A+A/627/A107 : CO obs. of major merger pairs at z=0 (Lisenfeld+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- GIDp Galaxy name (JHHMMSSss+DDMMSSs)
from Cao+ 2016, J/ApJS/222/16
19- 24 F6.4 --- z [0.0065/0.091] Redshift (after the correction
for Virgocentric flow)
26- 28 A3 --- Morph Galaxy morphology (1)
30- 34 F5.2 mag mISO [11.85/16.55] Magnitude from SExtractor
25mag/arcsec2 isophot or polygon aperture
36- 40 F5.2 mag mGAL [11.47/16.69] Model magnitude from GALFIT (2)
42- 45 F4.2 --- B/T [0/1] Bulge-to-total ratio
47- 51 F5.2 mag mB [12.57/22.31] Bulge magnitude
53- 56 F4.2 --- nB [1/8] bulge Sersic index
58- 61 F4.1 arcsec re [0/34.4] Bulge effective radius (3)
63- 66 F4.2 --- b/aB [0.02/0.98] Bulge axis ratio
68- 72 F5.1 deg PAB [-89.8/89.8] Bulge position angle (4)
74- 78 F5.2 mag mD [11.9/]?=99 Disk magnitude
80- 83 F4.1 arcsec rs [0/38.5]? Disk scale length (3)
85- 88 F4.2 --- b/aD [0.05/1]? Disk axis ratio
90- 94 F5.1 deg PAD [-89.8/88.5]? Disk position angle
96- 99 F4.2 --- Chi2 [1/1.9]? Reduced chi-square
101 I1 --- Flag [0/9] binary flag in decimal number (5)
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Note (1): Morphology and interaction type (Cao+ 2016, J/ApJS/222/16) as follows:
S = spiral
E = elliptical
J = "JUS": without clear interacting signs, "just" pair
I = "INT": with interaction signs (e.g., morphological distortions, tidal
tails and bridges, plumes etc.
M = "MER": merger
Note (2): Model magnitude, taken from GALFIT, except for distorted galaxies
(with Flag bit 2), for which this is exactly the same as the observed
magnitude.
Note (3): Bulge effective radius, noting that all radii (re or rs) less than
0.05 are recorded as 0.0.
Note (4): Bulge position angle (the counterclockwise angle between the major
axis of the ellipse and north, and the same for the disk position angle).
Note (5): Binary flag in decimal number:
Bit 0 (0, 0x0) = galaxy fitted separately;
Bit 1 (1, 0x1) = galaxy fitted in a pair;
Bit 2 (2, 0x10) = distorted galaxy with the bulge fitted by the model
and the total flux measured by photometry;
Bit 3 (4, 0x100) = the fitted bulge is brighter than the total flux of the
galaxy obtained in aperture photometry; and
Bit 4 (8, 0x1000) = the magnitude difference between the model and isophot
is significant.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 29-Sep-2022