J/MNRAS/471/3428 Damped Lyman Alpha systems equivalent width (Rao+, 2017)
The statistical properties of neutral gas at z < 1.65 from UV measurements of
Damped Lyman Alpha systems.
Rao S.M., Turnshek D.A., Sardane G.M., Monier E.M.
<Mon. Not. R. Astron. Soc., 471, 3428-3442 (2017)>
=2017MNRAS.471.3428R 2017MNRAS.471.3428R (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Ultraviolet ; Equivalent widths
Keywords: galaxies: evolution - galaxies: formation - galaxies: ISM -
quasars: absorption lines
Abstract:
We derive the statistical properties of neutral gas at redshifts
0.11<z<1.65 from ultraviolet (UV) measurements of quasar Lyα
absorption lines corresponding to 369 MgII systems with
Wλ27960≥0.3Å. In addition to the 41 damped Lyman alpha
(DLA) systems presented in Rao et al. (2006ApJ...636..610R 2006ApJ...636..610R, Cat.
J/ApJ/636/610), the current DLA sample includes 29 newly discovered
DLAs. Formally, this DLA sample includes 70 systems with
NHI≥2*1020atoms/cm2. We find that the incidence of DLAs, or the
product of their gas cross-section and their comoving number density,
can be described by nDLA(z)=(0.027±0.007)(1+z)(1.682±0.200)
over the redshift range of 0<z<5. The cosmic mass density of neutral
gas can be described by
ΩDLA(z)=(4.77±1.60)x10-4(1+z)(0.64±0.27). The
low-redshift column density distribution function is well fitted by a
power law of the form f(N)∼Nβ with β=-1.46±0.20. It is
consistent with the high redshift as well as z=0 estimates at the
high-column density end but lies between them at the low-column
density end. We discuss possible NHI and metallicity bias in Mg
II-selected DLA samples and show that such biases do not exist in the
current data at z<1.65. Thus, at least at z<1.65, DLAs found through
MgII selection statistically represent the true population of DLAs.
However, we caution that studies of DLA metallicities should take into
account the relative incidence of DLAs with respect to
W0λ2796^ (or gas velocity spread) in order to
Description:
We have used the MgII selection method to perform an unbiased survey
for DLA absorption line systems at 0.11<z<1.65. The results represent
an update to our previous findings reported in Rao et al.
(2006ApJ...636..610R 2006ApJ...636..610R, Cat. J/ApJ/636/610).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 92 60 The GALEX archival sample
table2.dat 83 16 The zabs≤0.4 MMT-HST COS sample
--------------------------------------------------------------------------------
See also:
J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Quasar Quasar name (JHHMMSS.s+DDMMSS)
18- 22 F5.3 --- zem Emission redshift
24- 29 F6.4 --- zabs Absorption redshift
31- 35 F5.3 0.1nm MgIIW27960 MgII λ27960 equivalent width
37- 41 F5.3 0.1nm e_MgIIW27960 rms uncertainty on MgIIW27960
43- 47 F5.3 0.1nm MgIIW28030 MgII λ28030 equivalent width
49- 53 F5.3 0.1nm e_MgIIW28030 rms uncertainty on MgIIW28030
55- 56 A2 --- l_MgIW28520 [≤ ] Limit flag on MgIW28520
(3σ level upper limit)
57- 61 F5.3 0.1nm MgIW28520 ? MgI λ28520 equivalent width
63- 67 F5.3 0.1nm e_MgIW28520 ? rms uncertainty on MgIW28520
69- 70 A2 --- l_FeIIW26000 [≤ ] Limit flag on FeIIW26000
(3σ level upper limit)
71- 75 F5.3 0.1nm FeIIW26000 ? FeII λ26000 equivalent width
77- 81 F5.3 0.1nm e_FeIIW26000 ? rms uncertainty on FeIIW26000
83- 87 F5.2 [cm-2] logNHI ? HI column density (1)
89- 92 F4.2 [cm-2] e_logNHI ? rms uncertainty on logNHI
--------------------------------------------------------------------------------
Note (1): entries indicate that the Lyα line could not be measured, but is
certainly not strong enough to be a DLA.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Quasar Quasar name (JHHMMSS.ss+DDMMSS.s)
21- 25 F5.3 --- zem Emission redshift
27- 32 F6.4 --- zabs Absorption redshift
34- 38 F5.3 0.1nm MgIIW27960 MgII λ27960 equivalent width
40- 44 F5.3 0.1nm e_MgIIW27960 rms uncertainty on MgIIW27960
46- 50 F5.3 0.1nm MgIIW28030 MgII λ28030 equivalent width
52- 56 F5.3 0.1nm e_MgIIW28030 rms uncertainty on MgIIW28030
58- 59 A2 --- l_MgIW28520 [≤ ] Limit flag on MgIW28520
(3σ level upper limit)
60- 64 F5.3 0.1nm MgIW28520 MgI λ28520 equivalent width
66- 70 F5.3 0.1nm e_MgIW28520 ? rms uncertainty on MgIW28520
71 A1 --- n_MgIW28520 [c] Note on MgIW28520
73- 77 F5.2 [cm-2] logNHI ? HI column density
79- 82 F4.2 [cm-2] e_logNHI ? rms uncertainty on logNHI
83 A1 --- n_logNHI [ab] Note on logNHI (1)
--------------------------------------------------------------------------------
Note (1): Notes as follows:
a = From Battisti et al. (2012ApJ...744...93B 2012ApJ...744...93B)
b = From Tumlinson et al. (2013ApJ...777...59T 2013ApJ...777...59T)
c = 3σ upper limit
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 27-May-2020