J/MNRAS/467/3172 HI photoionization rate at z<0.5 for 79 QSOs (Gaikwad+, 2017)
VoIgt profile Parameter Estimation Routine (VIPER):
H I photoionization rate at z < 0.5.
Gaikwad P., Srianand R., Choudhury T.R., Khaire V.
<Mon. Not. R. Astron. Soc., 467, 3172-3187 (2017)>
=2017MNRAS.467.3172G 2017MNRAS.467.3172G (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; H I data
Keywords: intergalactic medium - quasars: absorption lines -
cosmological parameters - cosmology: observations -
ultraviolet: galaxies
Abstract:
We have developed a parallel code called the VoIgt profile Parameter
Estimation Routine (VIPER) for automatically fitting the HI Lyα
forest seen in the spectra of quasi-stellar objects (QSOs). We
obtained the HI column density distribution function (CDDF) and
linewidth (b) parameter distribution for z<0.45 using spectra of 82
QSOs obtained using the Cosmic Origins Spectrograph and VIPER. The
consistency of these with existing measurements in the literature
validates our code. By comparing this CDDF with those obtained from
hydrodynamical simulations, we constrain the H I photoionization rate
(ΓHI) at z<0.45 in four redshift bins. VIPER, together with
the Code for Ionization and Temperature Evolution (CITE), which we
developed for GADGET-2, allows us to explore parameter space and
perform χ2 minimization to obtain ΓHI. We notice that
the b parameters from the simulations are smaller than those derived
from observations. We show that the observed b parameter distribution
and b versus logNHI scatter can be reproduced in simulations by
introducing subgrid-scale turbulence. However, it has very little
influence on the derived ΓHI. The ΓHI(z) obtained
here, (3.9±0.1)x10-14(1+z)4.98±0.11s-1, is in good agreement
with the values derived by us using flux-based statistics in a
previous article. These values are consistent with the hydrogen
ionizing ultraviolet (UV) background being dominated mainly by QSOs,
without needing any contribution from non-standard sources of UV
photons.
Description:
In this work, we constrain the HI photoionization rate HI and
its redshift evolution at z<0.45 from a sample of 79 QSOs obtained
with the Cosmic Origins Spectrograph on board the Hubble
Space Telescope using the HI column density distribution function
(CDDF). To explore the full ΓHI range, we have developed a
code 'VoIgt profile Parameter Estimation Routine' (VIPER) to
automatically fit the Lyα absorption lines with a Voigt profile.
This code is parallel and is written in PYTHON.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 79 51 List of studied QSOs
tablea1.dat 62 1284 Fitted parameters from the VIPER line catalogue
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See also:
J/A+A/562/A23 : VIMOS Public Extragalactic Survey (VIPERS) DR1 (Garilli+, 2014)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- QSO QSO name
25- 30 F6.4 --- z Redshift
32- 33 I2 h RAh Simbad right ascension (J2000)
35- 36 I2 min RAm Simbad right ascension (J2000)
38- 42 F5.2 s RAs Simbad right ascension (J2000)
44 A1 --- DE- Simbad declination sign (J2000)
45- 46 I2 deg DEd Simbad declination (J2000)
48- 49 I2 arcmin DEm Simbad declination (J2000)
51- 54 F4.1 arcsec DEs Simbad declination (J2000)
56- 79 A24 --- SName Simbad name
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- QSO QSO name
25- 32 F8.3 0.1nm lambda Wavelength
34- 38 F5.3 0.1nm e_lambda rms uncertainty on lambda
40- 44 F5.2 [cm-2] log(NHI) log of HI Column Density
46- 49 F4.2 [cm-2] e_log(NHI) rms uncertainty on log(NHI)
51- 56 F6.2 km/s b b parameter (in km/s)
58- 62 F5.2 km/s e_b rms uncertainty on b
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Nov-2019