J/ApJ/636/610 Damped Lyα systems at z<1.65 (Rao+, 2006)
Damped Lyα systems at z<1.65: the expanded Sloan Digital Sky Survey
Hubble Space Telescope sample.
Rao S.M., Turnshek D.A., Nestor D.B.
<Astrophys. J., 636, 610-630 (2006)>
=2006ApJ...636..610R 2006ApJ...636..610R
ADC_Keywords: QSOs ; Redshifts ; Equivalent widths
Keywords: galaxies: evolution - galaxies: formation - quasars: absorption lines
Abstract:
We present results of our Hubble Space Telescope Cycle 11 survey for
low-redshift (z<1.65) damped Lyα (DLA) systems in the UV spectra
of quasars selected from the Sloan Digital Sky Survey (SDSS) Early
Data Release (Cat. J/AJ/123/567). These quasars have strong
intervening MgII-FeII systems that are known signatures of high column
density neutral gas. In total, including our previous surveys, UV
observations of Lyα absorption in 197 MgII systems with z<1.65
and rest equivalent width (REW) W0λ2796≥0.3Å have now
been obtained.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 114 197 The MgII sample
refs.dat 139 35 References
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See also:
J/ApJ/635/123 : The SDSS damped Lyα survey: DR3 (Prochaska+, 2005)
J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- QSO QSO name
11- 14 F4.1 mag Vmag The V band magnitude
16- 20 F5.3 --- zem ? Redshift measured from emission lines
22- 27 F6.4 --- zabs Redshift measured from Mg II absorption line
29 A1 --- l_EW2600 Limit flag on EW2600 (1)
30- 35 F6.3 0.1nm EW2600 ? The FeII (2600Å) equivalent width (Å)
37- 41 F5.3 0.1nm e_EW2600 ? Error in EW2600
43- 47 F5.3 0.1nm EW2796 The MgII (2796Å) equivalent width (Å)
49- 53 F5.3 0.1nm e_EW2796 ? Error in EW2796
55 A1 --- l_EW2803 Limit flag on EW2803 (1)
56- 61 F6.3 0.1nm EW2803 The MgII (2803Å) equivalent width (Å)
63- 67 F5.3 0.1nm e_EW2803 ? Error in EW2803
69 A1 --- l_EW2852 Limit flag on EW2852 (1)
70- 75 F6.3 0.1nm EW2852 ? The MgI (2852Å) equivalent width (Å)
77- 81 F5.3 0.1nm e_EW2852 ? Error in EW2852
83- 90 A8 --- r_zabs References for zabs and equivalent widths (3)
92 A1 --- l_logN Limit flag on LogN (1)
93- 97 F5.2 [cm-2] logN ? Log of the HI column density
99 A1 --- f_logN [b] Flag on logN (4)
101-104 F4.2 [cm-2] E_logN ? Upper error in logN
106-109 F4.2 [cm-2] e_logN ? Lower error in logN
111 I1 --- Sel Selection criterion (5)
113-114 A2 --- UV UV spectrum from which Lyα information
was obtained (6)
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Note (1):
For systems other than those from Nestor (2004, Ph.D. thesis, Univ.
Pittsburgh), upper limits are either given by the authors or estimated
by us from the published spectrum. If the line is part of a blend,
then the rest equivalent width entered is an upper limit. The upper
limit is a 1σ upper limit if estimated by us from the published
spectrum. In some cases, the absorption line (λ2600 or
λ2852) was clearly visible in the spectrum but was not
identified by the authors since the rest equivalent width of the line
did not meet their detection criterion, usually 5σ. In these
cases, we estimated the equivalent width of the line from the spectrum
and tabulated the measurement as an upper limit. The trends that we
have established are evident from the measurements of rest equivalent
widths by the authors of the published spectra; our upper limit
measurements only serve to provide a certain degree of completeness to
our sample and, in fact, do not indicate or contribute to any trends
by themselves. We note that the quasar 0151+045 was erroneously
included in Table 4 of Rao & Turnshek (2000ApJS..130....1R 2000ApJS..130....1R). The MgII
system towards this quasar was detected after the galaxy-quasar pair
was known and is, therefore, a biased system. In addition, the
zabs=0.213 system towards 1148+386 and the zabs=0.1634 system towards
1704+608 were flagged as doubtful systems by Boisse et al.
(1992A&A...262..401B 1992A&A...262..401B). Finally, the nature of the zabs=1.3284 system
towards 1331+170 was deemed inconclusive from the low signal-to-noise
ratio IUE spectrum. Therefore, these four were eliminated from our
current MgII sample.
Note (3):
If no reference is specified, then data are from SDSS quasar spectral
analysis (2005ApJ...628..637N 2005ApJ...628..637N)
Note (4):
A "b" indicates that in two cases (the zabs=1.6101 system towards
1329+412 and the zabs=1.2528 system towards 1821+107), the HI column
density could not be determined because the Lyα and higher order
Lyman lines could not be fit with a unique value of N(HI) under the
assumption that the lines are damped. A large b value (greater than
100km/s) was necessary in both cases. Thus, it is clear that these
systems are not DLAs.
Note (5): Selection criterion used in the determination of nDLA,
defined as follows:
1 = EW2796≥0.3Å
2 = EW2796≥0.6Å
3 = EW2796≥0.6Å and EW2600≥0.5Å
4 = EW2796≥1.0Å and EW2600≥0.5Å
Note (6): Origin of UV spectrum as follows:
AR = HST or IUE archive;
06 = HST-cycle 6 program 6577, P.I. Rao;
09 = HST-cycle 9 program 8569, P.I. Rao;
11 = HST-cycle 11 program 9382, P.I. Rao;
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- Bibcode Bibcode
24- 54 A31 --- Aut Author's name
56-139 A84 --- Com Comment
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 04-Sep-2006