J/ApJ/935/121 2<zobs<4 quasars stacked spectrum (Yang+, 2022)
Metal Lines Associated with the Lya Forest from eBOSS Data.
Yang Li, Zheng Z., du Mas des Bourboux H., Dawson K., Pieri M.M.,
Rossi G., Schneider D.P., de la Macorra A., Gutierrez A.M.
<Astrophys. J., 935, 121 (2022)>
=2022ApJ...935..121Y 2022ApJ...935..121Y
ADC_Keywords: QSOs; Intergalactic medium; Spectra, ultraviolet
Keywords: Intergalactic medium ; Lyman alpha forest ; Metal line
absorbers
Abstract:
We investigate the metal species associated with the Lyα forest
in eBOSS quasar spectra. Metal absorption lines are revealed in
stacked spectra from cross-correlating the selected Lyα
absorbers in the forest and the flux fluctuation field. Up to 13 metal
species are identified as being associated with relatively strong
Lyα absorbers (those with flux fluctuations
-1.0<δLyα←0.6 and with a neutral hydrogen column density
of ∼1015-16/cm2) over the absorber redshift range of 2<zabs<4. The
column densities of these species decrease toward higher redshift and
for weaker Lyα absorbers. From modeling the column densities of
various species, we find that the column density pattern suggests
contributions from multiple gas components, both in the circumgalactic
medium (CGM) and the intergalactic medium (IGM). While the
low-ionization species (e.g., C II, Si II, and Mg II) can be explained
by high-density, cool gas (T∼104 K) from the CGM, the high-ionization
species may reside in low-density or high- temperature gas in the IGM.
The measurements provide inputs for modeling the metal contamination
in the Lyα forest baryon acoustic oscillation measurements.
Comparisons with metal absorptions in high-resolution quasar spectra
and hydrodynamic galaxy formation simulations can further elucidate
the physical conditions of these Lyα absorbers.
Description:
All quasar spectra used for this analysis were obtained using the
eBOSS spectrographs mounted on the 2.5m Sloan Foundation telescope at
the Apache Point Observatory, which are publicly available in the
sixteenth data release (DR16). The spectral resolution varies with
wavelength (3600-10400AA), from R=1800 to 2200; we adopt R=2000 in our
analysis, and this approximation has no effect on our results.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig3.dat 63 5051 *Illustration of the stacked spectrum
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Note on fig3.dat: By selecting -1.0<dLya←0.9 in the whole redshift
range of 2<zobs<4.
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
J/ApJ/596/768 : Optical depths in 19 QSOs (Schaye+, 2003)
J/MNRAS/456/3509 : Optically thin CIII absorbers at z∼2.5 (Kim+, 2016)
J/ApJ/833/283 : HIselected Lyman limit systems metallicities (Lehner+, 2016)
J/ApJ/887/5 : COS CGM compendium III. z≤1 Lyα syst. (Lehner+, 2019)
J/MNRAS/498/1951 : Lyman limit systems large quasar surveys (Fumagalli+, 2020)
J/ApJS/258/18 : Damped Lyα systems from SDSS DR16Q (Chabanier+, 2022)
Byte-by-byte Description of file: fig3.dat
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Bytes Format Units Label Explanations
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1- 20 E20.15 0.1nm Wave [900/2880] Vacuum wavelength
22- 42 E21.15 --- Flux [-0.96/0.05] Flux fluctuation field
44- 63 E20.15 --- e_Flux [0.0002/0.04] Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 02-Jul-2024