J/ApJ/853/95 Galaxies probing galaxies in PRIMUS. I. (Rubin+, 2018)
Galaxies probing galaxies in PRIMUS.
I. Sample, spectroscopy, and characteristics of the MgII-absorbing
circumgalactic medium.
Rubin K.H.R., Diamond-Stanic A.M., Coil A.L., Crighton N.H.M., Moustakas J.
<Astrophys. J., 853, 95 (2018)>
=2018ApJ...853...95R 2018ApJ...853...95R
ADC_Keywords: Galaxies, spectra; Intergalactic medium; Redshifts;
Equivalent widths; Magnitudes, absolute; Active gal. nuclei
Keywords: galaxies: evolution ; galaxies: halos ; quasars: absorption lines
Abstract:
The spectroscopy of background QSO sightlines passing close to
foreground galaxies is a potent technique for studying the
circumgalactic medium (CGM). However, QSOs are effectively point
sources, limiting their potential to constrain the size of
circumgalactic gaseous structures. Here we present the first large
Keck/Low-resolution Imaging Spectrometer (LRIS) and Very Large
Telescope (VLT)/Focal Reducer/Low-dispersion Spectrograph 2 (FORS2)
spectroscopic survey of bright (BAB<22.3) background galaxies whose
lines of sight probe MgIIλλ2796,2803 absorption from the
CGM around close projected foreground galaxies at transverse distances
10kpc<R⊥<150kpc. Our sample of 72 projected pairs, drawn from
the PRIsm MUlti-object Survey, includes 48 background galaxies that do
not host bright active galactic nuclei, and both star-forming and
quiescent foreground galaxies with stellar masses of
9.0<logM*/M☉<11.2 at redshifts of 0.35<zf/g<0.8. We detect
MgII absorption associated with these foreground galaxies with
equivalent widths of 0.25Å<W2796<2.6Å at >2σ
significance in 20 individual background sightlines passing within
R⊥<50kpc and place 2σ upper limits on W2796 of
≲0.5Å in an additional 11 close sightlines. Within
R⊥<50kpc, W2796 is anticorrelated with R⊥, consistent
with analyses of Mg ii absorption detected along background QSO
sightlines. Subsamples of these foreground hosts divided at
logM*/M☉=9.9 exhibit statistically inconsistent W2796
distributions at 30kpc<R⊥<50kpc, with the higher-M* galaxies
yielding a larger median W2796 by 0.9Å. Finally, we demonstrate
that foreground galaxies with similar stellar masses exhibit the same
median W2796 at a given R⊥ to within <0.2Å toward both
background galaxies and toward QSO sightlines drawn from the
literature. Analysis of these data sets constraining the spatial
coherence scale of circumgalactic MgII absorption is presented in a
companion paper.
Description:
Our galaxy pair sample is drawn from the PRIsm MUlti-object Survey
(PRIMUS), a spectroscopic survey of galaxies with redshifts in the
range 0<z<1.2 (Coil+ 2011ApJ...741....8C 2011ApJ...741....8C ; Cool+ 2013ApJ...767..118C 2013ApJ...767..118C).
Using the IMACS instrument on the Magellan Baade Telescope, PRIMUS
obtained redshifts for ∼120000 galaxies over 9.1deg2 to a magnitude
limit of i∼23.
Our follow-up spectroscopy was carried out with two instruments: the
LRIS on Keck I and the FORS2 on VLT-UT1.
Keck/LRIS observations were carried out during three observing runs on
2011 October 1 UT, 2012 January 20-21 UT, and 2012 December 13-15 UT.
Our VLT/FORS2 program (with ESO program IDs 088.A-0529A and
090.A-0485A) was carried out in visitor mode over three nights on 2011
November 25 UT and 2012 November 14-15 UT.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 91 Galaxy pair targets
table4.dat 83 72 Foreground galaxy properties and circumgalactic
medium (CGM) absorption line measurements
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See also:
II/261 : GOODS initial results (Giavalisco+, 2004)
J/AJ/127/3121 : TKRS catalog of GOODS-North Field (Wirth+, 2004)
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/ApJ/689/687 : GOODS-N spectroscopic survey (Barger+, 2008)
J/ApJ/679/194 : Low-z intergalactic medium. III. (Danforth+, 2008)
J/ApJ/690/1236 : COSMOS photometric redshift catalog (Ilbert+, 2009)
J/ApJ/714/1521 : Spectroscopy of galaxies around distant QSOs (Chen+, 2010)
J/ApJ/724/L176 : MgII absorbing gas around galaxies (Chen+, 2010)
J/ApJ/779/87 : MAGIICAT. III. Virial masses (Churchill+, 2013)
J/ApJ/770/138 : Metallicities of Lyman limit systems and DLA (Lehner+, 2013)
J/ApJ/776/136 : QPQ VI. HI absorption of z∼2 quasars (Prochaska+, 2013)
J/ApJ/762/L19 : Quasar pairs spectroscopy (Prochaska+, 2013)
J/ApJ/796/140 : Circumgalactic medium surrounding z∼2 QSOs (Prochaska+, 2014)
J/ApJ/794/156 : MgII/FeII absorption profile for 0.3<z<1.4 gal. (Rubin+, 2014)
J/ApJ/815/91 : z<0.16 CIV absorbers from HST/COS QSOs sp. (Burchett+, 2015)
J/MNRAS/452/2553 : Foreground-background quasar pairs (Johnson+, 2015)
J/ApJ/812/147 : Slug analysis of star clusters (Krumholz+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Pair [101/1613] Pair identification number
5 A1 --- f_Pair [*] Flag on Pair (G1)
7- 8 I2 h RAh Background galaxy hour of right ascension (J2000)
10- 11 I2 min RAm Background galaxy minute of RA (J2000)
13- 17 F5.2 s RAs Background galaxy second of RA (J2000)
19 A1 --- DE- Background galaxy sign of declination (J2000)
20- 21 I2 deg DEd Background galaxy degree of declination (J2000)
23- 24 I2 arcmin DEm Background galaxy arcminute of declination (J2000)
26- 29 F4.1 arcsec DEs Background galaxy arcsecond of declination (J2000)
31- 32 I2 h RAFh Foreground galaxy hour of right ascension (J2000)
34- 35 I2 min RAFm Foreground galaxy minute of RA (J2000)
37- 41 F5.2 s RAFs Foreground galaxy second of RA (J2000)
43 A1 --- DEF- Foreground galaxy sign of declination (J2000)
44- 45 I2 deg DEFd Foreground galaxy degree of declination (J2000)
47- 48 I2 arcmin DEFm Foreground galaxy arcminute of declination (J2000)
50- 53 F4.1 arcsec DEFs Foreground galaxy arcsecond of declination (J2000)
55- 58 F4.2 --- zb/g1 [0.3/3.1] Background galaxy redshift determined
from low-dispersion PRIMUS prism spectroscopy
60- 63 F4.2 --- zf/g1 [0.3/1.3] Foreground galaxy redshift determined
from low-dispersion PRIMUS prism spectroscopy
65- 71 F7.5 --- zb/g2 [0.07/3.1]? Background galaxy redshift determined
from our Keck/LRIS or VLT/FORS2 follow-up
spectroscopy
72 A1 --- f_zb/g2 Flag on zb/g2 (1)
74- 80 F7.5 --- zf/g2 [0.2/1.3]? Foreground galaxy redshift determined
from our Keck/LRIS or VLT/FORS2 follow-up
spectroscopy
81 A1 --- f_zf/g2 Flag on zf/g2 (1)
83- 86 F4.1 mag B(b/g) [19.8/22.8] Apparent B-band AB magnitude of
the background object
88- 91 F4.1 mag B(f/g) [21.1/23.6] Apparent B-band AB magnitude of
the foreground object
93- 97 F5.2 arcsec Sep [1.4/25.2] Angular separation
99 A1 --- n_Pair [l] l=longslit observation; column added by CDS
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Note (1): Flag as follows:
s = star
f = We failed to obtain spectra with a S/N sufficient to constrain the
redshift for those targets.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Pair [101/1613] Pair identifier
5 A1 --- f_Pair [*] Flag on Pair (G1)
7- 12 F6.4 --- zf/g [0.2/1.3] Foreground galaxy spectroscopic
redshift
14- 19 F6.2 mag BMag [-22.6/-18.8]? Absolute B band magnitude (1)
21- 24 F4.2 mag U-B [0.1/1.4]? The (U-B) color index (1)
26- 30 F5.2 [Msun] logM* [9/11.5] log stellar mass
32- 35 F4.1 Msun/yr SFR [0/19.2] Star Formation Rate
37- 41 F5.1 kpc Rperp [10.6/137] Projected separation
43- 46 F4.1 0.1/nm S/N-MgII [0.6/77] Median Signal-to-Noise within
±500km/s of the MgII2796Å line
48- 53 F6.3 0.1nm W2796 [-1.8/2.6] Equivalent width of MgII2796Å
line (2)
55- 59 F5.3 0.1nm e_W2796 [0.03/4.5] Uncertainty in W2796 (2)
61 A1 --- f_W2796 [b] Flag on W2796 (3)
63- 68 F6.3 0.1nm W2803 [-1.4/2.6] Equivalent width of MgII2803Å
line (2)
70- 74 F5.3 0.1nm e_W2803 [0.03/4.6] Uncertainty in W2803 (2)
76 A1 --- f_W2803 [b] Flag on W2803 (3)
78- 83 F6.1 km/s delv2796 [-605/258] Velocity offset between
flux-weighted centroid of 2796Å line and
zf/g
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Note (1): Rest-frame photometric measurements are not available from
Moustakas+ (2013ApJ...767...50M 2013ApJ...767...50M) for the objects with
blank entries in this column.
Note (2): In units of Angstroms.
Note (3):
b = transition affected by blending with Fe II absorption associated with
the background galaxy, or with the Lyα forest.
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Global note:
Note (G1):
* = a pair with a broad-line AGN in the background.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 29-Oct-2018