J/ApJ/800/7 Physical conditions of high redshift DLAs (Neeleman+, 2015)
Probing the physical conditions of atomic gas at high redshift.
Neeleman M., Prochaska J.X., Wolfe A.M.
<Astrophys. J., 800, 7 (2015)>
=2015ApJ...800....7N 2015ApJ...800....7N
ADC_Keywords: QSOs ; Redshifts ; Abundances ; Spectroscopy ; Interstellar medium
Keywords: galaxies: abundances; galaxies: evolution; galaxies: ISM; ISM: atoms;
evolution; quasars: absorption lines
Abstract:
A new method is used to measure the physical conditions of the gas in
damped Lyα systems (DLAs). Using high-resolution absorption
spectra of a sample of 80 DLAs, we are able to measure the ratio of
the upper and lower fine-structure levels of the ground state of C+
and Si+. These ratios are determined solely by the physical
conditions of the gas. We explore the allowed physical parameter space
using a Monte Carlo Markov chain method to constrain simultaneously
the temperature, neutral hydrogen density, and electron density of
each DLA. The results indicate that at least 5% of all DLAs have the
bulk of their gas in a dense, cold phase with typical densities of
∼100/cm3 and temperatures below 500K. We further find that the typical
pressure of DLAs in our sample is log(P/kB)=3.4(K/cm3), which is
comparable to the pressure of the local interstellar medium (ISM), and
that the components containing the bulk of the neutral gas can be
quite small with absorption sizes as small as a few parsecs. We show
that the majority of the systems are consistent with having densities
significantly higher than expected for a purely canonical warm neutral
medium, indicating that significant quantities of dense gas (i.e.,
nH>0.1/cm3) are required to match observations. Finally, we identify
eight systems with positive detections of Si II*. These systems have
pressures (P/kB) in excess of 20000K/cm3, which suggest that these
systems tag a highly turbulent ISM in young, star-forming galaxies.
Description:
Data are taken from the high-resolution spectrograph (HIRES) on the
Keck I telescope, which resulted in spectra with a typical resolution
of ∼8km/s. We further require that at least one of the transitions of
both levels of the C+ and Si+ are clear of any forest lines or
interloping features.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 80 Fine structure damped Lyα system (DLA) sample
table2.dat 93 80 Results of SiII* and CII* technique
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See also:
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/MNRAS/435/482 : DLA system from SDSS DR5 (Jorgenson+, 2013)
J/ApJ/769/54 : Spectroscopy of DLA systems (Neeleman+, 2013)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJS/171/29 : UCSD/Keck DLA Abundance Database (Prochaska+, 2007)
J/ApJ/649/L61 : SDSS J155810.16-003120.0 abundances (O'Meara+, 2006)
J/PASP/118/1077 : Metal-strong damped Lyα systems (Herbert-Fort+, 2006)
J/ApJ/635/123 : The SDSS-DR3 damped Lyα survey (Prochaska+, 2005)
J/ApJS/145/329 : Millennium Arecibo 21-cm Survey (Heiles+, 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/80] Running sequence number of the DLA
4- 14 A11 --- QSO QSO name
16- 21 F6.4 --- zabs [1.6/4.9] Absorption redshift of DLA
23- 27 F5.2 [cm-2] NHI [20.3/22.1] Log of the hydrogen column density
29- 32 F4.2 [cm-2] e_NHI [0.05/0.2] Error in NHI
34- 38 F5.2 [Sun] [M/H] [-2.6/-0.1] Log of metal "M" to hydrogen number
abundance
40- 43 F4.2 [Sun] e_[M/H] [0.05/0.5] Error in [M/H]
45- 46 A2 --- M Ion used for metallicity determination
(O, S, Fe, Si or Zn)
48 A1 --- l_NCIIs Limit flag on NCIIs
50- 54 F5.2 [cm-2] NCIIs [12.5/15.7] Log of column density of CII*
55 A1 --- f_NCIIs [*] * = fitted using VPFIT (1)
57- 60 F4.2 [cm-2] e_NCIIs [0.01/0.2]? Error in NCIIs
62 A1 --- l_NSiIIs Limit flag on NSiIIs
64- 68 F5.2 [cm-2] NSiIIs [11/13.7] Log of column density of SiII*
70- 73 F4.2 [cm-2] e_NSiIIs [0.02/0.2]? Error in NSiIIs
75 A1 --- l_NSiII Limit flag on NSiII
77- 81 F5.2 [cm-2] NSiII [13.3/16.6] Log of column density of SiII
82 A1 --- f_NSiII [*] * = fitted using VPFIT (1)
84- 87 F4.2 [cm-2] e_NSiII [0.01/0.5]? Error in NSiII
89 A1 --- N13 [NY] Part of the sample of Neeleman et al. 2013,
J/ApJ/769/54
91-101 A11 --- Ref Reference (2)
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Note (1): VPFIT is the Voigt profile fitting program
(http://www.ast.cam.ac.uk/~rfc/vpfit.html)
Note (2): Reference as follows:
1 = Lu et al. (1996ApJS..107..475L 1996ApJS..107..475L);
2 = Prochaska & Wolfe (1997ApJ...487...73P 1997ApJ...487...73P);
3 = Lu et al. (1998AJ....115...55L 1998AJ....115...55L);
4 = Prochaska & Wolfe (1999ApJS..121..369P 1999ApJS..121..369P);
5 = Petitjean et al. (2000A&A...364L..26P 2000A&A...364L..26P);
6 = Prochaska & Wolfe (2000ApJ...533L...5P 2000ApJ...533L...5P);
7 = Prochaska et al. (2001ApJS..137...21P 2001ApJS..137...21P);
8 = Ledoux et al. (2003MNRAS.346..209L 2003MNRAS.346..209L);
9 = Prochaska & Wolfe (2002ApJ...566...68P 2002ApJ...566...68P);
10 = Prochaska et al. (2003ApJ...595L...9P 2003ApJ...595L...9P);
11 = Dessauges-Zavadsky et al. (2004A&A...416...79D 2004A&A...416...79D);
12 = Khare et al. (2004ApJ...616...86K 2004ApJ...616...86K);
13 = Ledoux et al. (2006A&A...457...71L 2006A&A...457...71L);
14 = O'Meara et al. (2006, J/ApJ/649/L61);
15 = Herbert-Fort et al. (2006, J/PASP/118/1077);
16 = Dessauges-Zavadsky et al. (2007A&A...470..431D 2007A&A...470..431D);
17 = Prochaska et al. (2007, J/ApJS/171/29);
18 = Wolfe et al. (2008ApJ...681..881W 2008ApJ...681..881W);
19 = Jorgenson et al. (2010ApJ...722..460J 2010ApJ...722..460J);
20 = Kaplan et al. (2010PASP..122..619K 2010PASP..122..619K);
21 = Rafelski et al. (2012, J/ApJ/755/89);
22 = Kulkarni et al. (2012ApJ...749..176K 2012ApJ...749..176K);
23 = Berg et al. (2013MNRAS.434.2892B 2013MNRAS.434.2892B);
24 = This Work;
25 = Berg et al. (2015PASP..127..167B 2015PASP..127..167B);
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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- 2 I2 --- Seq [1/80] Running sequence number of the DLA
4- 14 A11 --- QSO QSO name
16- 21 F6.4 --- zabs [1.6/4.9] Absorption redshift of DLA
23- 26 F4.1 [cm-3] b1NH The 1σ lower limit to log(HI density)
28- 30 F3.1 [cm-3] B1NH The 1σ upper limit to log(HI density)
32- 35 F4.1 [cm-3] b2NH The 2σ lower limit to log(HI density)
37- 39 F3.1 [cm-3] B2NH The 2σ upper limit to log(HI density)
41- 44 F4.1 [cm-3] b1Ne The 1σ lower limit to log(electron density)
46- 49 F4.1 [cm-3] B1Ne The 1σ upper limit to log(electron density)
51- 54 F4.1 [cm-3] b2Ne The 2σ lower limit to log(electron density)
56- 59 F4.1 [cm-3] B2Ne The 2σ upper limit to log(electron density)
61- 63 F3.1 [K] b1T The 1σ lower limit to log(temperature)
65- 67 F3.1 [K] B1T The 1σ upper limit to log(temperature)
69- 71 F3.1 [K] b2T The 2σ lower limit to log(temperature)
73- 75 F3.1 [K] B2T The 2σ upper limit to log(temperature)
77- 80 F4.1 [K/cm3] b1P/k The 1σ lower limit to log(pressure/kB)
82- 84 F3.1 [K/cm3] B1P/k The 1σ upper limit to log(pressure/kB)
86- 89 F4.1 [K/cm3] b2P/k The 2σ lower limit to log(pressure/kB)
91- 93 F3.1 [K/cm3] B2P/k The 2σ upper limit to log(pressure/kB)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jun-2015