J/MNRAS/502/4743 Census of circumgalactic MgII at redshift z=<0.5 (Huang+, 2021)
A complete census of circumgalactic Mg II at redshift z=<0.5.
Huang Y.-H., Chen H.-W., Shectman S.A., Johnson S.D., Zahedy F.S.,
Helsby J.E., Gauthier J.-R., Thompson I.B.
<Mon. Not. R. Astron. Soc., 502, 4743-4761 (2021)>
=2021MNRAS.502.4743H 2021MNRAS.502.4743H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; QSOs ; Redshifts ; Equivalent widths ; Spectroscopy ;
Ultraviolet ; Optical
Keywords: surveys - galaxies: formation - galaxies: haloes -
intergalactic medium - quasars: absorption lines
Abstract:
This paper presents a survey of MgII absorbing gas in the vicinity of
380 random galaxies, using 156 background quasi-stellar objects (QSOs)
as absorption-line probes. The sample comprises 211 isolated (73
quiescent and 138 star-forming galaxies) and 43 non-isolated galaxies
with sensitive constraints for both MgII absorption and Hα
emission. The projected distances span a range from d=9 to 497kpc,
redshifts of the galaxies range from z=0.10 to 0.48, and rest-frame
absolute B-band magnitudes range from MB=-16.7 to -22.8. Our
analysis shows that the rest-frame equivalent width of MgII,
Wr(2796), depends on halo radius (Rh), B-band luminosity(LB),
and stellar mass (Mstar) of the host galaxies, and declines steeply
with increasing d for isolated, star-forming galaxies. At the same
time, Wr(2796) exhibits no clear trend for either isolated,
quiescent galaxies or non-isolated galaxies. In addition, the covering
fraction of MgII absorbing gas <κ> is high with <κ≫=60
per cent at <40kpc for isolated galaxies and declines rapidly to
<κ≳0 at d≥100 kpc. Within the gaseous radius, the incidence of
MgII gas depends sensitively on both Mstar and the specific star
formation rate inferred from Hα. Different from what is known
for massive quiescent haloes, the observed velocity dispersion of MgII
absorbing gas around star-forming galaxies is consistent with
expectations from virial motion, which constrains individual clump
mass to mcl≳105M☉ and cool gas accretion rate of
∼0.7-2M☉/yr. Finally, we find no strong azimuthal dependence of
MgII absorption for either star-forming or quiescent galaxies. Our
results demonstrate that multiple parameters affect the properties of
gaseous haloes around galaxies and highlight the need of a
homogeneous, absorption-blind sample for establishing a holistic
description of chemically enriched gas in the circumgalactic space.
Description:
To investigate the correlation between galaxy properties and MgII
absorbing gas at small projected distances, we need to obtain
spectroscopic data of both galaxies and QSO absorbers along common
sightlines. We utilize the MagE (Marshall et al. 2008SPIE.7014E..54M 2008SPIE.7014E..54M)
on the Magellan Clay Telescope to conduct a survey of MgII absorbers
at z<0.4. The high UV throughput of MagE from λ=3100Å
enables searches of MgII absorbers at redshift as low as 0.11.
Briefly, the QSO and galaxy pairs are selected from the SDSS DR6
catalogues (Adelman-McCarthy et al. 2008ApJS..175..297A 2008ApJS..175..297A, Cat. II/282).
To maximize the efficiency of searching MgII absorbers, we consider
galaxies at photometric redshifts of zphot=<0.4 that have background
QSOs in close projected distance d<Rgas. Rgas=130kpc is the
distinct boundary found by Chen & Tinker (2008ApJ...687..745C 2008ApJ...687..745C) using
23 galaxy-QSO pairs at intermediate redshifts of z∼0.4, beyond which
no MgII absorbers are found.
To establish a physical connection between galaxies and MgII absorbing
systems along nearby QSO sightlines, it is essential to have medium to
high resolution spectra to obtain precise and accurate redshift
measurements of these galaxies. We have obtained optical spectra of
218 galaxies that satisfy the criteria described above using the MagE
Spectrograph (Marshall et al. 2008SPIE.7014E..54M 2008SPIE.7014E..54M) at the Las Campanas
Observatory and the Double Imaging Spectrograph (DIS; Lupton 1995) on
the 3.5-m telescope at the Apache Point Observatory. Details about the
spectroscopic observation setups and data reduction are presented in
Chen et al. (2010ApJ...714.1521C 2010ApJ...714.1521C, Cat. J/ApJ/714/1521).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 380 Summary of Faint Galaxy Spectroscopy
table2.dat 82 156 Summary of the MagE spectroscopic observations
of SDSS QSOs
table3a.dat 106 211 Isolated galaxies and absorption systems
table3b.dat 106 71 Non-isolated galaxies and absorption systems
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 A24 --- Name Galaxy name (SDSSJHHMMSS.ss+DDMMSS.ss)
26- 27 I2 h RAh Right ascension (J2000)
29- 30 I2 min RAm Right ascension (J2000)
32- 36 F5.2 s RAs Right ascension (J2000)
38 A1 --- DE- Declination sign (J2000)
39- 40 I2 deg DEd Declination (J2000)
42- 43 I2 arcmin DEm Declination (J2000)
45- 49 F5.2 arcsec DEs Declination (J2000)
51- 54 F4.2 --- zphot ? Photometric redshift
56- 59 F4.2 --- e_zphot ? Error on zphot
61- 64 F4.1 mag rmag r-band magnitude
66- 69 A4 --- Inst Instrument used for the observations (1)
71- 81 A11 s ExpTime Exposure time
83- 91 A9 "Y:M:D" Date UT observation date
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Note (1): Instrument as follows:
DIS = Double Imaging Spectrograph (DIS; Lupton 1995) on the 3.5-m telescope
at the Apache Point Observatory
MagE = MagE Spectrograph (Marshall et al. 2008SPIE.7014E..54M 2008SPIE.7014E..54M) at the Las
Campanas Observatory
SDSS = SDSS DR14 (Abolfathi et al. 2018ApJS..235...42A 2018ApJS..235...42A)
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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- 24 A24 --- Name QSO name (SDSSJHHMMSS.ss+DDMMSS.ss)
26- 27 I2 h RAh Right ascension (J2000)
29- 30 I2 min RAm Right ascension (J2000)
32- 36 F5.2 s RAs Right ascension (J2000)
38 A1 --- DE- Declination sign (J2000)
39- 40 I2 deg DEd Declination (J2000)
42- 43 I2 arcmin DEm Declination (J2000)
45- 49 F5.2 arcsec DEs Declination (J2000)
51- 54 F4.2 --- zQSO Spectroscopic redshift of the QSO
56- 60 F5.2 mag umag u-band magnitude
62- 72 A11 s ExpTime Exposure time
74- 82 A9 --- Date UT observation date
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Byte-by-byte Description of file: table3[ab].dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- Name Galaxy name (SDSSJHHMMSS.ss+DDMMSS.ss)
26- 31 F6.1 arcsec dRA Offset in right ascension of the MgII
absorber
33- 38 F6.1 arcsec dDE Offset in declination of the MgII absorber
40- 45 F6.4 --- zgal Galaxy redshift
47- 51 F5.1 kpc Dist Distance
53- 57 F5.2 mag rmag r-band magnitude
59- 64 F6.2 mag BMAG Rest-frame absolute B-band magnitude
66- 69 F4.1 [Msun] logMass Logarithm of the stellar mass
71- 75 F5.1 kpc Rh Halo radius
77 A1 --- l_EWHa Limit flag on EWHa
79- 83 F5.1 0.1nm EWHa ? Hα equivalent width
85- 87 F3.1 0.1nm e_EWHa ? Error on EWHa
89- 94 F6.4 --- zabs ? Redshift of the MgII absorber
96 A1 --- l_W2796 Limit flag on W2796
98-101 F4.2 0.1nm W2796 ? MgII λ2796 equivalent width
103-106 F4.2 0.1nm e_W2796 ? Error on W2796
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 31-Oct-2023