J/ApJ/776/136 QPQ VI. HI absorption of z∼2 quasars (Prochaska+, 2013)
Quasars Probing Quasars.
VI. Excess H I absorption within one proper Mpc of z∼2 quasars.
Prochaska J.X., Hennawi J.F., Lee K.-G., Cantalupo S., Bovy J.,
Djorgovski S.G., Ellison S.L., Lau M.W., Martin C.L., Myers A.,
Rubin K.H.R., Simcoe R.A.
<Astrophys. J., 776, 136 (2013)>
=2013ApJ...776..136P 2013ApJ...776..136P
ADC_Keywords: QSOs ; Redshifts ; Spectroscopy ; Equivalent widths
Keywords: galaxies: halos; quasars: absorption lines
Abstract:
With close pairs of quasars at different redshifts, a background
quasar sightline can be used to study a foreground quasar's
environment in absorption. We use a sample of 650 projected quasar
pairs to study the HI Lyα absorption transverse to luminous, z∼2
quasars at proper separations of 30kpc<R⊥<1Mpc. In contrast to
measurements along the line-of-sight, regions transverse to quasars
exhibit enhanced HI Lyα absorption and a larger variance than
the ambient intergalactic medium, with increasing absorption and
variance toward smaller scales. Analysis of composite spectra reveals
excess absorption characterized by a Lyα equivalent width
profile W=2.3Å (R⊥/100kpc)-0.46. We also observe a high
(≃60%) covering factor of strong, optically thick HI absorbers (HI
column NHI>1017.3/cm2) at separations R⊥<200kpc, which
decreases to ∼20% at R⊥≃1Mpc, but still represents a
significant excess over the cosmic average. This excess of optically
thick absorption can be described by a quasar-absorber
cross-correlation function ξQA(r)=(r/r0)γ with a large
correlation length r0=12.5-1.4+2.7h-1Mpc (comoving) and
γ=1.68-0.30+0.14. The HI absorption measured around quasars
exceeds that of any previously studied population, consistent with
quasars being hosted by massive dark matter halos
Mhalo~1012.5M☉ at z∼2.5. The environments of these
massive halos are highly biased toward producing optically thick gas,
and may even dominate the cosmic abundance of Lyman limit systems and
hence the intergalactic opacity to ionizing photons at z∼2.5. The
anisotropic absorption around quasars implies the transverse direction
is much less likely to be illuminated by ionizing radiation than the
line-of-sight.
Description:
To better sample the gas surrounding quasars at small R⊥, we
have been conducting a comprehensive spectroscopic survey to discover
additional close quasar pairs and to follow-up the best examples for
our scientific interests. Close quasar pair candidates are selected
from a photometric quasar catalog (Bovy et al. 2011ApJ...729..141B 2011ApJ...729..141B,
2012ApJ...749...41B 2012ApJ...749...41B), and are confirmed via spectroscopy on 4m class
telescopes including: the 3.5m telescope at Apache Point Observatory
(APO), the Mayall 4m telescope at Kitt Peak National Observatory
(KPNO), the Multiple Mirror 6.5m Telescope, and the Calar Alto
Observatory (CAHA) 3.5m telescope.
Projected pair sightlines were then observed with 8m class telescopes
at the Keck, Gemini, MMT, Magellan, and LBT observatories to obtain
science-grade, absorption-line spectra (see table 2 for the journal of
observations).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 646 Quasars probing quasars VI (QPQ6) survey
table2.dat 51 105 Journal of observations
table3.dat 57 646 QPQ6 quasar redshifts
table4.dat 119 646 QPQ6 HI measurements
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See also:
VII/269 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004)
J/ApJ/775/78 : Lyman limit absorption systems in QSOs (Fumagalli+, 2013)
J/MNRAS/430/425 : VLT LBG Redshift Survey. III. (Bielby+, 2013)
J/ApJ/765/137 : HST survey for Lyman limit systems. II. (O'Meara+, 2013)
J/ApJ/763/37 : Metals in SDSS QSOs. I. 1.5<z<4.5 CIV abs. (Cooksey+, 2013)
J/ApJ/762/L19 : Quasar pairs spectroscopy (Prochaska+, 2013)
J/A+A/547/L1 : SDSS-III DR9 DLA catalogue (Noterdaeme+, 2012)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/740/91 : Lyα and OVI in galaxies around QSOs (Prochaska+, 2011)
J/ApJS/195/16 : HST survey for Lyman limit systems. I. (O'Meara+, 2011)
J/ApJ/736/42 : HST QSO Catalog (Ribaudo+, 2011)
J/MNRAS/414/28 : VLT Lyman-break gal. redshift survey. II. (Crighton+, 2011)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/719/1672 : SDSS binary quasars at high redshift. I. (Hennawi+, 2010)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/ApJ/718/392 : SDSS Lyman limit systems at z∼3.5 (Prochaska+, 2010)
J/MNRAS/392/1539 : Metal absorption systems in pairs of QSOs (Tytler+, 2009)
J/MNRAS/391/1457 : Lymanα forest in QSO pairs (Kirkman+, 2008)
J/ApJS/175/29 : Spectroscopy of QSO pairs (Marble+, 2008)
J/ApJ/675/1002 : Proximate DLA systems in SDSS-DR5 (Prochaska+, 2008)
J/AJ/133/2222 : Clustering of high-redshift QSOs from SDSS (Shen+, 2007)
J/ApJ/658/99 : Pairs of QSO in SDSS-DR4 (Myers+, 2007)
J/ApJ/651/61 : Opt. thick absorbers near luminous QSOs (Hennawi+, 2006)
J/ApJ/648/L97 : 2 QSOs supersolar super-Lyman limit syst. (Prochaska+ 2006)
J/AJ/131/1 : Binary quasars in the SDSS (Hennawi+, 2006)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/MNRAS/354/L25 : MgII absorbers in SDSS QSOs (Bouche+, 2004)
http://www.sdss.org/ : SDSS home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- f/g-Q Foreground quasar identifier
21- 26 F6.4 --- zfg [1.6/4.5] Foreground redshift (1)
28- 32 F5.2 [cW/m2/nm] L912 [28/32]? Log of 912Å luminosity;
erg/s/cm2/Å (2)
34- 38 F5.2 [mW/m2] Lbol [45/48]? Log of bolometric luminosity;
erg/s/cm2 (2)
40- 58 A19 --- b/g-Q Background quasar identifier
60- 64 F5.3 --- zbg [1.7/4.9] Background redshift
66- 68 I3 kpc b [31/999] Impact parameter R⊥
70- 74 I5 --- gUV [2/17964]? Enhancement in flux relative
to the extragalactic UV background (2)
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Note (1): As described in Section 2.3.2 and listed in Table 3.
Note (2): Pairs without a value do not have a reliable photometric measurement.
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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- 19 A19 --- b/g-Q Background quasar identifier (1)
21- 28 A8 --- Obs Observatory
30- 33 A4 --- Inst Instrument (2)
35- 45 A11 "YYYY/MMM/DD" Date Observation date (3)
47- 51 I5 s Exp [300/16800] Exposure time (4)
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Note (1): The majority of the f/g quasars were observed at the same time and
for the same exposure.
Note (2): Our quasars probing quasars (QPQ) survey has been gathering follow-up
optical spectra on large-aperture telescopes using spectrometers with
a diverse range of capabilities including instrument as follows:
ESI = Echellette Spectrometer and Imager (R∼5000)
LRIS = Low Resolution Imaging Spectrograph (wavelength coverage
∼3300-4200Å and FWHM resolution of 125km/s).
HIRES = High Resolution Echelle Spectrometer on the twin 10m Keck telescopes
(R∼35000; observations described in QPQ3: Prochaska & Hennawi,
2009ApJ...690.1558P 2009ApJ...690.1558P)
GMOS = Gemini Multi-Object Spectrograph on the 8m Gemini North and South
telescopes (FWHM∼125km/s)
MagE = Magellan Echellette Spectrograph (R=4000; λ∼3050-10300Å)
MIKE = Magellan Inamori Kyocera Echelle spectrometers on the 6m Magellan
telescopes (R=28000 (R=22000) for blue (red) side;
λ∼3300-9150Å)
MODS = Multi-Object Double Spectrograph on the Large Binocular Telescope
(LBT) (FWHM∼200km/s; λ∼3000-10000Å)
See section 2 for further details.
Note (3): UT date of the first night this object was observed by our program
with this instrument.
Note (4): Total exposure time for the spectrum covering Lyα using this
instrument.
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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- 19 A19 --- f/g-Q Foreground quasar identifier
21- 28 A8 --- Inst Source spectrum (G1)
31- 46 A16 --- Lines Emission lines used in zem
48- 53 F6.4 --- zfg [1.6/4.5] Emission line derived redshift
55- 57 I3 km/s e_zfg [272/794] Uncertainty in zfg
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- f/g-Q Foreground quasar identifier
21- 39 A19 --- b/g-Q Background quasar identifier
41- 43 I3 kpc b Impact parameter
45- 49 A5 --- Inst1 Source spectrum (G1)
51- 55 F5.3 --- zfg [1.6/4.5] Foreground redshift
57- 59 I3 --- S/N [6/205] Signal-to-noise per rest-frame Å (3)
61- 65 F5.2 --- [0/1.2] Average flux (4)
67- 71 F5.2 --- DelF [-0.5/1] Value defined in Equ. 4 (5)
73- 77 I5 km/s delv [-1733/1553]? Velocity offset (6)
79- 84 F6.1 0.1nm LWave [3204/6615]? Lower wavelength of Lyα
analysis (Å)
86- 91 F6.1 0.1nm UWave [3217/6634]? Upper wavelength of Lyα
analysis (Å)
93 A1 --- l_WLya Limit flag on WLya
94- 98 F5.2 0.1nm WLya [0.2/23.7]? Rest equivalent width (7)
100-103 F4.2 0.1nm e_WLya [0.01/0.3]? Uncertainty in WLya
105 A1 --- l_logNH Limit flag on logNH
107-111 F5.2 [cm-2] logNH [14.3/21.3]? Log of H I column density
113-116 F4.2 [cm-2] e_logNH [0.1/0.4]? Uncertainty in logNH
118-119 I2 --- OT [-1/1]? Optical thick flag (8)
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Note (3): At the position of Lyα, S/NLyα. This quantity
is measured from the original continuum.
Note (4): In a series of contiguous Δv=2000km/s windows.
Note (5): Equation 4 as:
δ_ = (IGM-Δν)/IGM
with IGM, the mean-flux at each redshift and Δν,
the average normalized flux. See section 3.
Note (6): zLyα to zfg. Note that absorption lines were assessed
only for data with S/NLyα>9.5.
Note (7): Of the strongest absorption system within 1500km/s of zfg.
Note (8): Indicates an assessment of whether the system is optically thick
at the Lyman limit (-1=Thin; 0=Ambiguous; 1=Thick).
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Global notes:
Note (G1): Sources are:
SDSS = Sloan Digital Sky Survey Quasar Catalog release 7
(Schneider et al. 2010, VII/260);
BOSS = Baryonic Oscillation Spectroscopic Survey data release 9
(Paris et al. 2009, VII/269);
LRIS600 = Keck/Low Resolution Imaging Spectrograph R600 grating;
LRIS300 = Keck/Low Resolution Imaging Spectrograph R300 grating;
LRISb = Keck/Low Resolution Imaging Spectrograph blue channel;
ESI = Keck/Echellette Spectrometer and Imager;
MagE = Magellan Echellette Spectrograph;
MODS = LBT/Multi-Object Double Spectrograph
GMOS = Gemini Multi-Object Spectrograph;
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History:
From electronic version of the journal
References:
Hennawi et al. Paper I. 2006ApJ...651...61H 2006ApJ...651...61H Cat. J/ApJ/651/61
Hennawi & Prochaska Paper II. 2007ApJ...655..735H 2007ApJ...655..735H
Prochaska & Hennawi Paper III. 2009ApJ...690.1558P 2009ApJ...690.1558P
Hennawi & Prochaska Paper IV. 2013ApJ...766...58H 2013ApJ...766...58H
Prochaska et al. Paper V. 2013ApJ...762L..19P 2013ApJ...762L..19P Cat. J/ApJ/762/L19
Prochaska et al. Paper VII. 2014ApJ...796..140P 2014ApJ...796..140P
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Mar-2015