J/MNRAS/462/4197 HI 21-cm absorption in redshifted galaxies (Curran+, 2016)
A comparative study of intervening and associated H I 21-cm absorption
profiles in redshifted galaxies.
Curran S.J., Duchesne S.W., Divoli A., Allison J.R.
<Mon. Not. R. Astron. Soc., 462, 4197-4207 (2016)>
=2016MNRAS.462.4197C 2016MNRAS.462.4197C (SIMBAD/NED BibCode)
ADC_Keywords: H I data ; QSOs ; Redshifts ; Radio lines ; Redshifts
Keywords: methods: data analysis - galaxies: active - galaxies: high redshift -
galaxies: ISM - quasars: absorption lines - radio lines: galaxies
Abstract:
The star-forming reservoir in the distant Universe can be detected
through HI 21-cm absorption arising from either cool gas associated
with a radio source or from within a galaxy intervening the sightline
to the continuum source. In order to test whether the nature of the
absorber can be predicted from the profile shape, we have compiled and
analysed all of the known redshifted (z≥0.1) HI 21-cm absorption
profiles. Although between individual spectra there is too much
variation to assign a typical spectral profile, we confirm that
associated absorption profiles are, on average, wider than their
intervening counterparts. It is widely hypothesized that this is due
to high-velocity nuclear gas feeding the central engine, absent in the
more quiescent intervening absorbers. Modelling the column density
distribution of the mean associated and intervening spectra, we
confirm that the additional low optical depth, wide dispersion
component, typical of associated absorbers, arises from gas within the
inner parsec. With regard to the potential of predicting the absorber
type in the absence of optical spectroscopy, we have implemented
machine learning techniques to the 55 associated and 43 intervening
spectra, with each of the tested models giving a ≥80 per cent
accuracy in the prediction of the absorber type. Given the
impracticability of follow-up optical spectroscopy of the large number
of 21-cm detections expected from the next generation of large radio
telescopes, this could provide a powerful new technique with which to
determine the nature of the absorbing galaxy.
Description:
Unlike at lower redshifts, most of the z≥0.1 detections are already
compiled (in Tables 1 and 2, which are updated from Curran & Whiting,
2010ApJ...712..303C 2010ApJ...712..303C and Curran, 2010MNRAS.402.2657C 2010MNRAS.402.2657C, respectively).
However, the raw data were generally unavailable and so the spectra
were acquired from the literature by digitizing the available figures.
For this, we used the GetData Graph Digitizer2 package for all the
spectra, except those in Srianand et al. (2015MNRAS.451..917S 2015MNRAS.451..917S) and Yan
et al. (2016AJ....151...74Y 2016AJ....151...74Y), which were constructed from Gaussian
parameters presented.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 137 57 The features of the z≥0.1 associated 21-cm absorbers
table2.dat 137 49 The features of the z≥0.1 intervening 21-cm absorbers
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Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- IAU IAU name
14- 21 F8.6 --- zweight ? Mean-weighted absorption redshift
24 I1 --- ng ? Number of Gaussian components required to
fit the spectrum
26- 29 I4 --- FWZI ? Full width at zero intensity
31- 38 F8.6 --- taupeak ? Peak observed optical depth
40- 47 F8.6 --- B_taupeak ? Maximum peak observed optical depth
49- 56 F8.6 --- b_taupeak ? Minimum peak observed optical depth
57- 63 F7.1 km/s Dv ? Average offset of the components
from zweight
65- 71 F7.4 km/s Dv/FWZI ? Average offset of the components
from zweight and full width at zero intensity
75- 77 I3 km/s FWHM ? Average full width at half-maxima
79- 81 I3 km/s B_FWHM ? Average full width at half-maxima
83- 87 F5.1 km/s b_FWHM ? Average full width at half-maxima
89- 92 A4 --- Ref Reference for the 21-cm absorption (1)
93-137 A45 --- Com Comments
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Note (1): References as follows:
B01 = Briggs, de Bruyn & Vermeulen (2001A&A...373..113B 2001A&A...373..113B)
B83 = Briggs & Wolfe (1983ApJ...268...76B 1983ApJ...268...76B)
C92 = Carilli, Perlman & Stocke (1992ApJ...400L..13C 1992ApJ...400L..13C)
C93 = Carilli, Rupen & Yanny (1993ApJ...412L..59C 1993ApJ...412L..59C)
C98 = Carilli et al. (1998ApJ...494..175C 1998ApJ...494..175C)
C11 = Chandola, Sirothia & Saikia (2011MNRAS.418.1787C 2011MNRAS.418.1787C)
C99 = Chengalur, de Bruyn & Narasimha (1999A&A...343L..79C 1999A&A...343L..79C)
C07a = Curran et al. (2007MNRAS.382L..11C 2007MNRAS.382L..11C)
C07b = Curran et al. (2007MNRAS.382.1331C 2007MNRAS.382.1331C)
C11a = Curran et al. (2011MNRAS.413.1165C 2011MNRAS.413.1165C)
C11b = Curran et al. (2011MNRAS.414L..26C 2011MNRAS.414L..26C)
C13 = Curran et al. (2013MNRAS.429.3402C 2013MNRAS.429.3402C)
D04 = Darling et al. (2004ApJ...613L.101D 2004ApJ...613L.101D)
D78 = Davis & May (1978ApJ...219....1D 1978ApJ...219....1D)
E12 = Ellison et al. (2012MNRAS.424..293E 2012MNRAS.424..293E)
G15 = Gereb et al. (2015A&A...575A..44G 2015A&A...575A..44G. Cat. J/A+A/575/A44)
G06 = Gupta et al. (2006MNRAS.373..972G 2006MNRAS.373..972G)
G09a = Gupta et al. (2009, ASP Conf. Ser. Vol. 407, 67)
G09b = Gupta et al. (2009MNRAS.398..201G 2009MNRAS.398..201G)
G12 = Gupta et al. (2012A&A...544A..21G 2012A&A...544A..21G)
G13 = Gupta et al. (2013A&A...558A..84G 2013A&A...558A..84G)
I03 = Ishwara-Chandra, Dwarakanath, & Anantharamaiah (2003, JA&A, 24, 37)
K01a = Kanekar & Chengalur (2001MNRAS.325..631K 2001MNRAS.325..631K)
K01b = Kanekar, Ghosh & Chengalur (2001A&A...373..394K 2001A&A...373..394K)
K03a = Kanekar & Briggs (2003A&A...412L..29K 2003A&A...412L..29K)
K03b = Kanekar & Chengalur (2003A&A...399..857K 2003A&A...399..857K)
K09 = Kanekar et al. (2009MNRAS.396..385K 2009MNRAS.396..385K)
K12 = Kanekar et al. (2013MNRAS.428..532K 2013MNRAS.428..532K)
K14a = Kanekar et al. (2014MNRAS.438.2131K 2014MNRAS.438.2131K)
K14b = Kanekar (2014ApJ...797L..20K 2014ApJ...797L..20K)
L01 = Lane & Briggs (2001ApJ...561L..27L 2001ApJ...561L..27L)
L96 = Lovell et al. (1996ApJ...472L...5L 1996ApJ...472L...5L)
M89 = Mirabel (1989ApJ...340L..13M 1989ApJ...340L..13M)
M99 = Moore, Carilli & Menten (1999ApJ...510L..87M 1999ApJ...510L..87M)
M01 = Morganti et al. (2001MNRAS.323..331M 2001MNRAS.323..331M)
O06 = Orienti, Morganti & Dallacasa (2006A&A...457..531O 2006A&A...457..531O)
P00 = Peck et al. (2000ApJ...534..104P 2000ApJ...534..104P)
P99 = Peck, Taylor & Conway (1999ApJ...521..103P 1999ApJ...521..103P)
R76 = Roberts et al. (1976AJ.....81..293R 1976AJ.....81..293R)
S10 = Salter et al. (2010ApJ...715L.117S 2010ApJ...715L.117S)
S12 = Srianand et al. (2012MNRAS.421..651S 2012MNRAS.421..651S)
S15 = Srianand et al. (2015MNRAS.451..917S 2015MNRAS.451..917S)
U91 = Uson, Bagri & Cornwell (1991, Phys. Rev. Lett. 67, 3328)
V89 = van Gorkom et al. (1989AJ.....97..708V 1989AJ.....97..708V)
V03 = Vermeulen et al. (2003A&A...404..861V 2003A&A...404..861V)
Y16 = Yan et al. (2016AJ....151...74Y 2016AJ....151...74Y)
Y07 = York et al. (2007MNRAS.382L..53Y 2007MNRAS.382L..53Y)
Z15 = Zwaan et al. (2015MNRAS.453.1268Z 2015MNRAS.453.1268Z)
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History:
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(End) Patricia Vannier [CDS] 23-Apr-2018