J/ApJ/818/113 HST observations of QSOs with medium spectra (Neeleman+, 2016)
The H I content of the Universe over the past 10 Gyrs.
Neeleman M., Prochaska J.X., Ribaudo J., Lehner N., Howk J.C., Rafelski M.,
Kanekar N.
<Astrophys. J., 818, 113 (2016)>
=2016ApJ...818..113N 2016ApJ...818..113N (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Spectra, ultraviolet
Keywords: evolution; galaxies: evolution; galaxies: ISM; intergalactic medium;
quasars: absorption lines
Abstract:
We use the Hubble Space Telescope (HST) archive of ultraviolet (UV)
quasar spectroscopy to conduct the first blind survey for damped
Lyα absorbers (DLAs) at low redshift (z<1.6). Our statistical
sample includes 463 quasars with spectral coverage spanning a total
redshift path Δz=123.3 or an absorption path ΔX=229.7.
Within this survey path, we identify 4 DLAs defined as absorbers with
HI column density NHI≥1020.3/cm2, which implies an incidence per
absorption length lDLA(X)=0.017-0.008+0.014 at a median survey
path redshift of z=0.623. While our estimate of lDLA(X) is lower
than earlier estimates at z∼0 from HI 21cm emission studies, the
results are consistent within the measurement uncertainties. Our data
set is too small to properly sample the NHI frequency distribution
function f(NHI,X), but the observed distribution agrees with
previous estimates at z>2. Adopting the z>2 shape of f(NHI, X), we
infer an HI mass density at z∼0.6 of ρHIDLA=0.25-0.12+0.20.
This is significantly lower than previous estimates from targeted DLA
surveys with the HST, but consistent with results from low-z HI 21cm
observations, and suggests that the neutral gas density of the
universe has been decreasing over the past 10Gyr.
Description:
To measure the amount of neutral hydrogen between z∼0.01 and z∼1.6, we
have assembled a large sample of quasars observed with medium
resolution spectrographs on the HST Space Telescope Imaging
Spectrograph (STIS), Faint Object Spectrograph (FOS) or Cosmic Origins
Spectrograph (COS).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 136 1017 QSO sample
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/MNRAS/452/217 : HI cosmological mass density at z=5 (Crighton+, 2015)
J/ApJ/779/161 : MgII absorbers in 0.4<z<2.3 SDSS QSOs (Seyffert+, 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/736/42 : HST QSO Catalog (Ribaudo+, 2011)
J/A+A/505/1087 : DLAs in SDSS-DR7 (Noterdaeme+, 2009)
J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/MNRAS/354/L31 : SDSS DR2 QSO and DLA properties (Murphy+, 2004)
J/ApJS/140/143 : HST FOS spectral atlas (Bechtold+, 2002)
Byte-by-byte Description of file:table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- QSO QSO identifier (JHHMM+DDMM)
13- 36 A24 --- AltQSO Alternate QSO identifier
38- 39 I2 h RAh Hour of Right Ascension (J2000)
41- 42 I2 min RAm Minute of Right Ascension (J2000)
44- 47 F4.1 s RAs Second of Right Ascension (J2000)
49 A1 --- DE- Sign of the Declination (J2000)
50- 51 I2 deg DEd Degree of Declination (J2000)
53- 54 I2 arcmin DEm Arcminute of Declination (J2000)
56- 59 F4.1 arcsec DEs Arcsecond of Declination (J2000)
61- 65 F5.3 --- zem [0/4.7] Emission redshift of the QSO
67- 70 A4 --- Inst Instrument used ("COS", "FOS", "STIS")
72- 88 A17 --- Grate Grating used
90 I1 --- FSrch ? Flag for search path (1)
92- 96 F5.3 --- zShmin [0.01/1.7]? Minimum Redshift of Search Path
98-102 F5.3 --- zShmax [0.09/1.7]? Maximum Redshift of Search Path
104 I1 --- FStat ? Flag for statistical path (2)
106-110 F5.3 --- zStmin [0.01/1.7]? Minimum Redshift of Statistical Path
112-116 F5.3 --- zStmax [0.01/1.7]? Maximum Redshift of Statistical Path
118-136 A19 --- Prop Proposal Identification Number
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Note (1): Flag for search path as follows:
0 = Low S/N or Bad Spectrum;
1 = Included;
2 = BAL Quasar.
Note (2): Flag for statistical path as follows:
0 = Non-Statistical;
1 = Statistical;
2 = Galaxy Sample.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-May-2016