J/other/RAA/24.E5005 Close major-merger pairs at z=0 (He+, 2024)
Close Major-merger Pairs at z = 0: Star-forming Galaxies with Pseudobulges.
He C., Xu C., Lisenfeld U., Dai Y.S., Fang T., Huang J., Wang W., Yu Q.
<Res. Astron. Astrophys., 24, 055005 (2024)>
=2024RAA....24e5005H 2024RAA....24e5005H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, interacting ; Galaxies, photometry ; Photometry, SDSS ;
Infrared
Keywords: galaxies: evolution - galaxies: interactions -
galaxies: star formation - galaxies: structure - galaxies: bulges -
galaxies: photometry
Abstract:
We present a study of star-forming galaxies (SFGs) with pseudobulges
(bulges with Sersic index n<2) in a local close major-merger galaxy
pair sample (H-KPAIR). With data from new aperture photometries in the
optical and near-infrared bands (aperture size of 7kpc) and from the
literature, we find that the mean Age of central stellar populations
in Spirals with pseudobulges is consistent with that of disky galaxies
and is nearly constant against the bulge-to-total ratio (B/T). Paired
Spirals have a slightly lower fraction of pure disk galaxies
(B/T≤0.1) than their counterparts in the control sample. Compared to
SFGs with classical bulges, those with pseudobulges have a higher
(>2σ) mean of specific star formation rate (sSFR) enhancement
(sSFRenh=0.33±0.07 versus sSFRenh=0.12±0.06) and broader scatter
(by ∼1dex). The eight SFGs that have the highest sSFRenh in the sample
all have pseudobulges. A majority (69%) of paired SFGs with strong
enhancement (having sSFR more than 5 times the median of the control
galaxies) have pseudobulges. The Spitzer data show that the
pseudobulges in these galaxies are tightly linked to
nuclear/circum-nuclear starbursts. Pseudobulge SFGs in S+S and in S+E
pairs have significantly (>3σ) different sSFR enhancement, with
the means of sSFRenh=0.45±0.08 and -0.04±0.11, respectively. We
find a decrease in the sSFR enhancements with the density of the
environment for SFGs with pseudobulges. Since a high fraction (5/11)
of pseudobulge SFGs in S+E pairs are in rich groups/clusters (local
density N1Mpc≥7), the dense environment might be the cause for their
low sSFRenh.
Description:
Here we present a study of SFGs with pseudobulges (bulges with Sersic
index n<2) in a local close major-merger galaxy pair sample (H-KPAIR).
The sample is taken from He et al. (2022ApJS..261...34H 2022ApJS..261...34H,
Cat. J/ApJS/261/34) who did 2-D galfit decompositions to study the B/T
dependence of the star formation enhancement of paired SFGs. New
aperture photometries in the SDSS u, r, i-bands and the 2MASS Ks -band
are carried out for the sample to investigate the stellar populations
in the central part (D=7kpc) of the galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 132 Spiral Galaxies in H-KPAIR
table2.dat 74 176 Aperture photometry and model fits of the
H-KPAIR Sample
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See also:
J/ApJS/261/34 : Bulge-disk decomposition of H-KPAIR sample (He+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Galaxy name (JHHMMSSss+DDMMSSs)
19- 24 F6.4 --- z Redshift
26- 27 A2 --- PairType [SS SE] Pair type (1)
29 A1 --- BulgeType [pc] Bulge type (2)
31 I1 --- isFSFG [0/1] is the galaxy an SFG,
1 for true and 0 for false
33- 37 F5.2 mag rmag Magnitude of SDSS r-band
39- 42 F4.2 --- B/T Bulge-to-Total ratio
44- 48 F5.2 [Msun] logM* Stellar mass
50- 54 F5.2 --- sSFRenh Specific star formation rate enhancement
56- 57 I2 --- N1Mpc Number of galaxies brighter than Mr=-19.7mag
within a D=1Mpc circle centered on the galaxy
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Note (1): Pair type as follows:
SS = Spiral+Spiral pair
SE = Spiral+Elliptical pair
Note (2): Bulge type as follows:
p = pseudobulge
c = classical-bulge
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Galaxy name (JHHMMSSss+DDMMSSs)
19 A1 --- Type [SE] Galaxy type: S = Spiral, E = Elliptical
21- 25 F5.2 mag umag Magnitude of SDSS u-band in 7 kpc aperture
27- 30 F4.2 mag e_umag Magnitude of SDSS u-band 7 kpc aperture error
32- 36 F5.2 mag rmag Magnitude of SDSS r-band in 7 kpc aperture
38- 41 F4.2 mag e_rmag Magnitude of SDSS r-band 7 kpc aperture error
43- 47 F5.2 mag imag Magnitude of SDSS i-band in 7 kpc aperture
49- 52 F4.2 mag e_imag Magnitude of SDSS i-band 7 kpc aperture error
54- 58 F5.2 mag Ksmag Magnitude of 2MASS Ks-band in 7 kpc aperture
60- 63 F4.2 mag e_Ksmag Magnitude of 2MASS Ks-band 7 kpc aperture error
65- 69 F5.2 Gyr Age Stellar age generated from u-r-i-Ks color
71- 74 F4.2 mag AV Attenuation of V-band generated
from u-r-i-Ks color
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 01-Aug-2025