J/ApJS/240/15 HST/COS UV obs. of low-z SDSS galaxy groups (Stocke+, 2019)
The ultraviolet detection of diffuse gas in galaxy groups.
Stocke J.T., Keeney B.A., Danforth C.W., Oppenheimer B.D., Pratt C.T.,
Berlind A.A., Impey C., Jannuzi B.
<Astrophys. J. Suppl. Ser., 240, 15 (2019)>
=2019ApJS..240...15S 2019ApJS..240...15S
ADC_Keywords: Active gal. nuclei; Spectra, ultraviolet; Velocity dispersion;
Redshifts; Galaxies, spectra; Optical
Keywords: galaxies: evolution ; galaxies: groups: general ; galaxies: halos ;
intergalactic medium ; quasars: absorption lines
Abstract:
A small survey of the UV-absorbing gas in 12 low-z galaxy groups has
been conducted using the Cosmic Origins Spectrograph on board the
Hubble Space Telescope. Targets were selected from a large,
homogeneously selected sample of groups found in the Sloan Digital Sky
Survey. A critical selection criterion excluded sight lines that pass
close (<1.5 virial radii) to a group galaxy, to ensure absorber
association with the group as a whole. Deeper galaxy redshift
observations are used both to search for closer galaxies and also to
characterize these 1013.5-1014.5M☉ groups, the most massive
of which are highly virialized with numerous early-type galaxies
(ETGs). This sample also includes two spiral-rich groups, not yet
fully virialized. At group-centric impact parameters of 0.3-2Mpc,
these signal-to-noise ratios = 15-30 spectra detected HI absorption in
7 of 12 groups; high (OVI) and low (SiIII) ion metal lines are present
in two-thirds of the absorption components. None of the three most
highly virialized, ETG-dominated groups are detected in absorption.
Covering fractions ≳50% are seen at all impact parameters probed, but
do not require large filling factors despite an enormous extent.
Unlike halo clouds in individual galaxies, group absorbers have radial
velocities that are too low to escape the group potential well without
doubt. This suggests that these groups are "closed boxes" for galactic
evolution in the current epoch. Evidence is presented that the cool
and warm group absorbers are not a pervasive intra-group medium
(IGrM), requiring a hotter (T∼106-107K) IGrM to be present to
close the baryon accounting.
Description:
For each of the nine sight lines in our HST observing program (#14277:
Stocke, PI), a single COS G130M spectrum was obtained over several
orbits in HST Cycle 23 (see Table 1 for details). The G130M spectrum
of CSO 1022 was taken by program #13444 in the previous HST cycle.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 12 HST/COS observations
table2.dat 87 12 Group properties from SDSS analysis of Paper III
(Berlind+, 2006, J/ApJS/167/1)
table3.dat 84 12 Detections/non-detections in group sight lines
table7.dat 80 629 Members of all 12 galaxy groups
table8.dat 75 12 Adopted group properties
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJ/559/654 : Lyα absorption systems. V. (Chen+, 2001)
J/ApJS/167/1 : Galaxy groups and clusters from SDSS (Berlind+, 2006)
J/ApJ/679/194 : Low-z intergalactic medium. III. (Danforth+, 2008)
J/ApJ/740/91 : Lyα and OVI in galaxies around quasars (Prochaska+, 2011)
J/ApJ/788/119 : Properties of the highly ionized gas of quasars (Lehner+, 2014)
J/ApJ/791/128 : Basic galaxy data for spiral-rich group members (Stocke+, 2014)
J/MNRAS/449/3263 : Extended galaxy halo gas through HI and OVI (Johnson+, 2015)
J/ApJ/804/79 : HST/COS obs. of QSOs within 600kpc of M31 (Lehner+, 2015)
J/MNRAS/449/2345 : Mass & luminosity of maxBCG galaxies groups (Proctor+, 2015)
J/ApJ/814/40 : Nearby galaxy filaments with UV obs. (Wakker+, 2015)
J/ApJ/817/111 : HST/COS survey of z<0.9 AGNs. I. (Danforth+, 2016)
J/ApJS/230/6 : HST -COS & -STIS absorption-line spectrosc. II. (Keeney+, 2017)
J/ApJS/237/11 : Galaxy z survey near HST/COS AGN sight lines (Keeney+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GID [12833/50433] Group ID
7- 21 A15 --- AGN AGN target abbreviated name
23 A1 --- f_AGN Flag on AGN (1)
25- 29 F5.3 --- zAGN [0.1/0.6] AGN redshift
31- 37 A7 "M/D/Y" Date UT date of observation
39- 45 A7 "M/D/Y" Coadd Date of the coadded visit
47- 50 F4.1 ks Exp [4.8/25.4] Exposure time
52 A1 --- l_Ffuv Limit flag on Ffuv
53- 54 I2 10-17W/m2/nm Ffuv [1/12] HST/COS FUV flux
in 10-15erg/s/cm2/Å
55 A1 --- f_Ffuv Flag on Ffuv (1)
57- 58 I2 --- S/N [11/29] Signal-to-noise ratio
60- 71 A12 --- Notes Notes (observing program(s))
72 A1 --- f_Notes Flag on Notes (1)
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Note (1): Flag as follows:
a = Partial LLS at source redshift mostly eliminates OVI sensitivity.
c = Two groups are probed by the CSO 1022 sight line.
d = Archival data set from Program 13444 (PI: Wakker).
e = Two groups are probed by the FBQS J1519+2838 sight line.
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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- 5 I5 --- GID [12833/50433] Group ID
7- 8 I2 --- N0 [3/10] Number of group members
from SDSS analysis
10- 16 F7.3 deg RAdeg [129.4/243.6] Group centroid right ascension
in decimal degrees (J2000)
18- 22 F5.3 deg e_RAdeg [0.01/0.07] RAdeg uncertainty
24- 29 F6.3 deg DEdeg [-2.1/50.8] Group centroid declination
in decimal degrees (J2000)
31- 35 F5.3 deg e_DEdeg [0.009/0.06] DEdeg uncertainty
37- 43 F7.5 --- z0 [0.1/0.2] Group redshift from SDSS analysis
45- 51 F7.5 --- e_z0 [0.0002/0.001] z0 uncertainty
53- 57 F5.2 [Msun] logM0 [13.7/14.7] log of group mass
from SDSS analysis
59- 62 F4.2 [Msun] e_logM0 [0.2/0.4] logM0 uncertainty
64- 66 I3 km/s Sig0 [322/632] Group velocity dispersion
from SDSS analysis
68- 77 F10.6 deg RAsdeg QSO sight line right ascension (J2000)
79- 87 F9.6 deg DEsdeg QSO sight line declination (J2000)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GID [12833/50433] Group ID
7- 9 F3.1 --- rho/R0 [0.3/1.4] Impact parameter (2)
11- 25 A15 --- AGN AGN abbreviated name (as in Table 1)
27- 84 A58 --- Abs Absorption component notes
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Note (2): Impact parameter between the SDSS group barycenter and the QSO sight
line, normalized by the group virial radius.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GID [12833/50433] Group identification number
7- 25 A19 --- Name Member name (1)
27- 36 F10.6 deg RAdeg [129/243.7] Right ascension (J2000)
38- 46 F9.6 deg DEdeg [-2.3/51] Declination (J2000)
48- 54 F7.5 --- zgal [0.1/0.2] Galaxy spectroscopic redshift
56- 61 F6.3 Lsun Lum [0.1/16.6] Galaxy luminosity
63- 63 A1 --- Type Galaxy's spectral type (2)
65- 68 I4 kpc drho [13/2912] Projected spatial displacement (3)
70- 74 I5 km/s dv [-1956/1537] Velocity displacement (3)
76- 80 F5.1 % fmem [21.2/100] Probability of group membership (4)
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Note (1): A galaxy identifier, which is either a SDSS "ObjID" or, for galaxies
without SDSS redshifts, a string in the style of
Keeney+ (2018, J/ApJS/237/11).
Note (2): Type as follows:
E = emission-line galaxies,
A = absorption-line galaxies, and
C = composite galaxies that show both emission and absorption.
Note (3): Displacement as measured from the original SDSS group center
(Table 2).
Note (4): fmem is the percentage of the Monte Carlo trials in which a galaxy
was identified as a group member.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- GID [12833/50433] Group ID
7- 13 F7.3 deg RAGdeg [129.4/243.6] Adopted right ascension (J2000)
15- 20 F6.3 deg DEGdeg [-2.1/50.8] Adopted declination (J2000)
22- 28 F7.5 --- zgrp [0.1/0.2] Adopted group redshift
30- 32 I3 --- Ngrp [6/116] Number of group galaxies
34- 38 F5.2 [Msun] logMgrp [13.5/14.7] log of total group mass (3)
40- 43 I4 kpc Rgrp [667/1553] Group virial radius
45- 47 I3 km/s Siggrp [270/628] Group velocity dispersion
49- 52 I4 kpc Robs [178/1546] Observed group radius
54- 56 I3 km/s Sigobs [170/569] Observed velocity dispersion
58- 61 F4.2 --- rho*/Rgrp [0.3/2.1] Impact parameter from the group
centroid as a fraction of Rgrp
ρ*/Rgrp (4)
63- 65 I3 --- Delrho [128/704] Δρ value (5)
67- 70 I4 --- Delnu [-823/271] Δν value (5)
72- 75 F4.1 --- fsp [31.3/68] Group's spiral fraction (6)
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Note (3): Mgrp is calculated assuming Υgrp=2.5
Note (4): ρ* is the impact parameter between the adopted group center and
the COS sight line in kpc.
Note (5): Δρ and Δν are offsets from the SDSS group
centroids (RAdeg and DEdeg in Table 2).
Note (6): An estimate of the group's spiral fraction derived from the spectral
types of the adopted group members (see text for details).
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History:
From electronic version of the journal
Referencs:
Savage et al. Paper I. 2014ApJS..212....8S 2014ApJS..212....8S
Stocke et al. Paper II. 2014ApJ...791..128S 2014ApJ...791..128S Cat. J/ApJ/791/128
Berlind et al. Paper III. 2006ApJS..167....1B 2006ApJS..167....1B Cat. J/ApJS/167/1
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-May-2019