J/ApJ/740/91 Lyα and OVI in galaxies around quasars (Prochaska+, 2011)
Probing the intergalactic medium/galaxy connection.
V. On the origin of Lyα and O VI absorption at z < 0.2.
Prochaska J.X., Weiner B., Chen H.-W., Mulchaey J., Cooksey K.
<Astrophys. J., 740, 91 (2011)>
=2011ApJ...740...91P 2011ApJ...740...91P
ADC_Keywords: Galaxies, spectra ; Spectra, ultraviolet ; QSOs ; Redshifts ;
Equivalent widths
Keywords: galaxies: structure - intergalactic medium -
large-scale structure of universe - quasars: absorption lines
Abstract:
We analyze the association of galaxies with Lyα and OVI
absorption, the most commonly detected transitions of the low-z
intergalactic medium (IGM), in the fields of 14 quasars with
zem=0.06-0.57. Confirming previous studies, we observe a high
covering fraction for Lyα absorption to impact parameter
ρ=300h-172kpc: 33/37 of our L>0.01L* galaxies show Lyα
equivalent width WLyα≥50 mÅ. Galaxies of all luminosity
L>0.01L* and spectral type are surrounded by a diffuse and ionized
circumgalactic medium (CGM), whose baryonic mass is estimated at
∼1010.5±0.3M☉ for a constant NH=1019cm-2. The
virialized halos and extended CGM of present-day galaxies are
responsible for most strong Lyα absorbers
(WLyα>300mÅ) but cannot reproduce the majority of observed
lines in the Lyα forest. We conclude that the majority of
Lyα absorption with WLyα=30-300mÅ occurs in the
cosmic web predicted by cosmological simulations and estimate a
characteristic width for these filaments of ∼400h-172kpc.
Regarding OVI, we observe a near unity covering fraction to
ρ=200h-172kpc for L>0.1L* galaxies and to
ρ=300h-172kpc for sub-L* (0.1 L*<L<L*) galaxies. Similar to
our Lyα results, stronger OVI systems (W1031>70mÅ) arise in
the virialized halos of L>0.1L* galaxies. Unlike Lyα, the weaker
OVI systems (W1031∼30mÅ) arise in the extended CGM of sub-L*
galaxies. The majority of OVI gas observed in the low-z IGM is
associated with a diffuse medium surrounding individual galaxies with
L∼0.3L* and rarely originates in the so-called warm-hot IGM (predicted
by cosmological simulations.
Description:
We have recently published a survey of galaxies in the fields of 20
quasars with bright UV fluxes (Paper IV, Cat. J/ApJS/193/28), the
majority of which have UV spectral data sets that yield precise
measurements of Lyα and/or OVI absorption. The galaxy survey was
performed with the WFCCD spectrometer on the 100" Dupont telescope and
was designed to achieve a high level of completeness to R≤19.5mag
galaxies in an ∼20'x20' field centered on each quasar.
In the following IGM/galaxy analysis, we leverage published surveys
for Lyα and OVI absorption in the quasar spectra of our fields.
This corresponds to 13 sight lines with UV spectra from the HST/GHRS,
HST/STIS, and/or FUSE instruments (Table 1).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 111 14 Fields analyzed from WFCCD spectrometer at
Las Campanas Observatory
table8.dat 100 134 Galaxies within 1Mpc of a QSO sightline
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See also:
J/ApJS/193/28 : Galaxy survey around 20 UV-bright quasars (Prochaska+, 2011)
J/ApJ/714/1521 : Spectroscopy of galaxies around distant QSOs (Chen+, 2010)
J/ApJ/701/1219 : Galaxy survey in 3 QSO fields (Chen+, 2009)
J/ApJS/177/39 : Survey of low-redshift OVI absorbers (Tripp+, 2008)
J/ApJ/679/194 : Low-z intergalactic medium. III. (Danforth+, 2008)
J/ApJ/676/262 : PKS1302-102 intergalactic absorption system (Cooksey+, 2008)
J/ApJ/643/680 : Imaging & spectroscopy around PKS 0405-123 (Prochaska+, 2006)
J/ApJ/617/718 : Atomic data and EW for PKS 0405-123 (Prochaska+, 2004)
J/ApJ/559/654 : Lyα absorption systems. V. (Chen+, 2001)
J/ApJ/498/77 : Lyα absorption systems. III. (Chen+, 1998)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Field Quasar name
13- 14 I2 h RAh Hour of right ascension (J2000)
16- 17 I2 min RAm Minute of right ascension (J2000)
19- 22 F4.1 s RAs Second of right ascension (J2000)
24 A1 --- DE- Sign of declination (J2000)
25- 26 I2 deg DEd Degree of declination (J2000)
28- 29 I2 arcmin DEm Arcminute of declination (J2000)
31- 32 I2 arcsec DEs Arcsecond of declination (J2000)
34- 38 F5.3 --- zem Emission redshift
40- 83 A44 --- Set HST UV spectroscopic data sets
85- 87 I3 ks FUSE ? Total FUSE integration time (Cat. VI/129)
89- 97 A9 --- Lya Lyα reference(s) (G1)
99-107 A9 --- OVI OVI reference(s) (G1)
109-111 I3 --- Nsp ? Number of spectroscopically determined galaxy
redshifts for objects with 0.005<z<zem
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Field Field identification
13- 14 I2 h RAh Hour of Right Ascension (J2000)
16- 17 I2 min RAm Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the Declination (J2000)
26- 27 I2 deg DEd Degree of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 35 F4.1 arcsec DEs Arcsecond of Declination (J2000)
37- 42 F6.4 --- zgal Galaxy redshift (1)
44- 46 I3 kpc rho Impact parameter (1)
48- 52 F5.3 --- L/L* Luminosity of the galaxy
54- 59 F6.4 --- zabsL ? The Lyα absorption redshift
62 A1 --- l_WLya Limit flag on WLya
63- 66 I4 10-13m WLya ? Equivalent width of Lyα (in mÅ)
68 A1 --- l_NHI Limit flag on NHI
70- 74 F5.2 [cm-2] NHI ? Log of H I column density
76 I1 --- r_NHI ? Reference for NHI (G1)
78- 83 F6.4 --- zabsO ? The O.VI absorption redshift
86 A1 --- l_WOVI Limit flag on WOVI
87- 90 I4 10-13m WOVI ? Equivalent width of O VI; milli-Angstroms
92 A1 --- l_NOVI Limit flag on NOVI
94- 98 F5.2 [cm-2] NOVI ? Log of O VI column density
100 I1 --- r_NOVI ? Reference for NOVI (G1)
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Note (1): Galaxies within ±400km/s in redshift were grouped together and
only the member with smallest impact parameter is tabulated here.
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Global notes:
Note (G1): Reference as follows:
1 = Tripp et al. (2008, Cat. J/ApJS/177/39);
2 = Thom & Chen (2008ApJ...683...22T 2008ApJ...683...22T);
3 = Danforth & Shull (2008, Cat. J/ApJ/679/194);
4 = Danforth et al. (2006ApJ...640..716D 2006ApJ...640..716D);
5 = Penton et al. (2004ApJS..152...29P 2004ApJS..152...29P);
6 = Chen & Mulchaey (2009, Cat. J/ApJ/701/1219);
9 = This paper.
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Nomenclature note:
In table 8, galaxies are <[PWC2011] JHHMMSS.s+DDMMSS> for Simbad.
History:
From electronic version of the journal
References:
Prochaska et al., Paper I 2004ApJ...617..718P 2004ApJ...617..718P, Cat. J/ApJ/617/718
Chen et al., Paper II 2005ApJ...629L..25C 2005ApJ...629L..25C
Prochaska et al., Paper III 2006ApJ...643..680P 2006ApJ...643..680P, Cat. J/ApJ/643/680
Prochaska et al., Paper IV 2011ApJS..193...28P 2011ApJS..193...28P, Cat. J/ApJS/193/28
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-Feb-2013