J/MNRAS/477/5625 SDSSDR12 eclipsing damped Lyalpha systems (Fathivavsari+, 2018)
Eclipsing damped Lyα systems in the Sloan Digital Sky Survey Data
Release 12.
Fathivavsari H., Petitjean P., Jamialahmadi N., Khosroshahi H.G.,
Rahmani H., Finley H., Noterdaeme P., Paris I., Srianand R.
<Mon. Not. R. Astron. Soc. 477, 5625 (2018)>
=2018MNRAS.477.5625F 2018MNRAS.477.5625F (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Equivalent widths
Keywords: quasars: absorption lines - quasars: emission lines
Abstract:
We present the results of our automatic search for proximate damped
Lyα absorption (PDLA) systems in the quasar spectra from the
Sloan Digital Sky Survey Data Release 12. We constrain our search to
those PDLAs lying within 1500km/s from the quasar to make
sure that the broad DLA absorption trough masks most of the strong
Lyα emission from the broad-line region (BLR) of the quasar.
When the Lyα emission from the BLR is blocked by these so-called
eclipsing DLAs, narrow Lyα emission from the host galaxy could
be revealed as a narrow emission line (NEL) in the DLA trough. We
define a statistical sample of 399 eclipsing DLAs with
logN(HI)≥21.10. We divide our statistical sample into three
subsamples based on the strength of the NEL detected in the DLA
trough. By studying the stacked spectra of these subsamples, we found
that absorptions from high ionization species are stronger in DLAs
with stronger NEL in their absorption core. Moreover, absorption from
the excited states of species like SIII are also stronger in DLAs with
stronger NEL. We also found no correlation between the luminosity of
the Lyα NEL and the quasar luminosity. These observations are
consistent with a scenario in which the DLAs with stronger NEL are
denser and physically closer to the quasar. We propose that these
eclipsing DLAs could be the product of the interaction between
infalling and outflowing gas. High-resolution spectroscopic
observation would be needed to shed some light on the nature of these
eclipsing DLAs.
Description:
We follow a new approach to search for eclipsing DLA candidates in the
BOSS spectra. Our searching procedure is based on the detection of
metal absorption lines in quasar spectra. We take into account only
quasars with the emission redshift higher than zem=2.0, as this is
the minimum redshift for which the Lyα transition spectral
region falls on the observed spectral window.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 605 QSOs redshifts and Lyα integrated flux
table2.dat 94 605 Rest EWs of CII λ1334, SiII λ1526,
AlII λ1670, and FeII λ2344
transitions
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See also:
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSS SDSS name (HHMMSS.ss+ddMMSS.s)
20- 24 F5.3 --- z SDSS emission redshift
26- 30 F5.2 [cm-2] logNHI HI column density
32- 36 F5.3 --- zabs Absorption redshift measured from fitting low
ionization metal absorption lines
38- 42 F5.3 --- zLya ?=- Lyα redshift of the narrow
Lyα emission (1)
44 A1 --- l_IF Limit flag on IF
45- 49 F5.1 mW/m2 IF Integrated flux of the narrow Lyα
emission (erg/cm2/s) (2)
51 A1 --- Sample [NS] Sample (3)
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Note (1): No redshift is reported when no emission is detected in the
DLA trough.
Note (2): In cases where no Lyα emission is detected in the DLA trough we
report an upper limit which is determined by integrating the pixel values in
the DLA trough over a velocity extent of 1000km/s
Note (3): Sample as follows:
S = DLAs from the statistical sample
N = others sample
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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- 18 A18 --- SDSS SDSS name (HHMMSS.ss+ddMMSS.s)
20- 24 F5.3 --- zabs Absorption redshift
26- 30 F5.3 0.1nm EWCII ? CII 1334 equivalent width measured
directly by integrating the pixel values
over the line profile (1) (2)
32- 34 A3 --- --- [-]
36- 40 F5.3 0.1nm e_EWCII ? rms uncertainty on EWCII
42- 46 F5.3 0.1nm EWSiII ? SiII 1526 equivalent width measured
directly by integrating the pixel values
over the line profile (1)
48- 52 F5.3 0.1nm EWSiIIF ? Si II 1526 equivalent width determined
from a fit to the absorption line
54- 58 F5.3 0.1nm e_EWSiII ? rms uncertainty on EWSiII
59 A1 --- neEWSiII [i] i for infinity
60- 64 F5.3 0.1nm EWAlII ? AlII 1670 equivalent width measured
directly by integrating the pixel values
over the line profile (1)
66- 70 F5.3 0.1nm EWAlIIF ? AlII 1670 equivalent width determined
from a fit to the absorption line
72- 76 F5.3 0.1nm e_EWAlII ? rms uncertainty on EWAlII
78- 82 F5.3 0.1nm EWFeII ? FeII 2344 equivalent width measured
directly by integrating the pixel values
over the line profile (1)
84- 88 F5.3 0.1nm EWFeIIF ? FeII 2344equivalent width determined
from a fit to the absorption line
90- 94 F5.3 0.1nm e_EWFeII ? rms uncertainty on EWFeII
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Note (1): when the spectral region of a transition is too noisy, no EW is
reported for that species.
Note (2): Since CII absorption is typically blended with CII*, we only report
the EW of the whole CII+CII* absorption feature determined from direct
integration of the pixel values.
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Acknowledgements:
Hassan Fathivavsari, h.fathie(at)gmail.com
(End) Patricia Vannier [CDS] 19-Apr-2018