J/ApJ/888/85 Ghostly strong Lya absorbers in SDSS DR12 (Fathivavsari, 2020)
Ghostly strong Lyα absorbers: tracers of gas flows in the close vicinity
of quasars?
Fathivavsari H.
<Astrophys. J., 888, 85 (2020)>
=2020ApJ...888...85F 2020ApJ...888...85F
ADC_Keywords: QSOs; Spectra, optical; Intergalactic medium; Redshifts
Keywords: Interstellar absorption ; Interstellar line absorption ; Quasars ;
Active galactic nuclei ; Quasar absorption line spectroscopy ;
Intergalactic medium ; Interstellar dust extinction ;
Circumgalactic medium ; Extragalactic astronomy ; Galaxy structure ;
Galactic winds
Abstract:
We have searched the Sloan Digital Sky Survey Data Release 12 for
ghostly strong Lyα (DLA) systems. These systems, located at the
redshift of the quasars, show strong absorption from low-ionization
atomic species but reveal no HI Lyα absorption. Our search has,
for the first time, resulted in a sample of 30 homogeneously selected
ghostly absorbers with zQSO>2.0. Thirteen of the ghostly absorbers
exhibit absorption from other HI Lyman series lines. The lack of
Lyα absorption in these absorbers is consistent with them being
dense and compact with projected sizes smaller than the broad-line
region of the background quasar. Although uncertain, the estimated
median HI column density of these absorbers is logN(HI)∼21.0. We
compare the properties of ghostly absorbers with those of eclipsing
DLAs that are high-column-density absorbers, located within 1500km/s
of the quasar emission redshift and showing strong Lyα emission
in their DLA trough. We discover an apparent sequence in the observed
properties of these DLAs, with ghostly absorbers showing wider HI
kinematics, stronger absorptions from high-ionization species, CII and
SiII excited states, and a higher level of dust extinction. Since we
estimate that all these absorbers have similar metallicities,
logZ/Z☉~-1.0, we conclude that ghostly absorbers are part of the
same population as eclipsing DLAs, except that they are denser and
located closer to the central active galactic nuclei.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 30 Ghostly absorbers
table2.dat 47 149378 Search results
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See also:
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
J/MNRAS/354/L31 : SDSS DR2 QSO and DLA properties (Murphy+, 2004)
J/PASP/116/622 : SDSS damped Lyα survey: DR1 (Prochaska+, 2004)
J/PASP/118/1077 : Metal-strong damped Lyα systems (Herbert-Fort+, 2006)
J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006)
J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)
J/MNRAS/392/998 : Damped Lymanα systems (Ellison+, 2009)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/A+A/547/L1 : SDSS-III DR9 DLA catalogue (Noterdaeme+, 2012)
J/other/ApSS/353.347 : 398-710nm Sun spectral atlases (Fathivavsari+, 2014)
J/AJ/149/203 : Reddening of ∼35000 quasars from SDSS (Krawczyk+, 2015)
J/MNRAS/462/3285 : XQ-100. X-shooter quasar spectra (Perrotta+, 2016)
J/A+A/585/A87 : Quasar composite made from bright QSOs (Selsing+, 2016)
J/MNRAS/464/L56 : DLA properties and EW of 36 QSOs (Berg+, 2017)
J/MNRAS/477/5625 : SDSSDR12 eclipsing damped Lya systems (Fathivavsari+, 2018)
J/A+A/618/A184 : SDSS J151349.52+035211.28 Xshooter spectra (Ranjan+, 2018)
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; J2000)
20- 24 F5.3 --- zQSO [2.038/3.39] Quasar emission redshift
26- 30 F5.3 --- zabs [2.035/3.387] Ghostly absorber absorption
redshift
32- 36 F5.2 --- logNHI [20.3/21.8]? Logarithm of HI column
density (1)
38- 41 I4 0.1pm FeII1 [39/2373]? Rest equivalent width (in
mÅ) of the FeIIλ1608
absorption line
43- 46 I4 0.1pm FeII2 [674/4319]? Rest equivalent width (in
mÅ) of the FeIIλ2382
absorption line
48- 51 I4 0.1pm FeII3 [569/5869]? Rest equivalent width (in
mÅ) of the FeIIλ2600
absorption line
53- 56 I4 0.1pm AlII [278/3278]? Rest equivalent width (in
mÅ) of the AlIIλ1670
absorption line
58- 61 I4 0.1pm MgII [1562/4414]? Rest equivalent width (in
mÅ) of the MgIIλ2796
absorption line
63- 66 I4 0.1pm CII [1001/5105]? Rest equivalent width (in
mÅ) of the CIIλ1334
absorption line
68- 71 F4.2 10-19W/m2/nm Fnu [0.5/5.8] Quasar flux in
10-17erg/s/cm2/Å
73- 76 F4.1 --- Lnu [41.3/42.3] Logarithm of QSO luminosity
at 1500Å
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Note (1): Here we only report the HI column densities of the systems for which
at least one extra Lyman series transition other than Lyα is observed.
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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- 15 A15 --- ID SDSS Plate-MJD-Fiber identifier
17- 23 F7.5 --- z [2.04/5.47] Quasar spectroscopic redshift
25- 27 A3 --- S1 Member of the S-1 subsample? (1)
29- 31 A3 --- S2 Member of the S-2 subsample? (1)
33- 35 A3 --- S3 Member of the S-3 subsample? (1)
37- 39 A3 --- S4 Member of the S-4 subsample? (1)
41- 43 A3 --- S5 Member of the S-5 subsample? (1)
45- 47 A3 --- Ghost Member of the ghostly absorbers?
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Note (1): Subsample as follows:
S-1 = BOSS quasars that have emission redshift higher than zem=2.0, zero
balnicity index, and continuum-to-noise ratio above 4.0.
S-2 = S1QSO sample cross-correlated with the metal absorption template;
systems with high significance ≥4σ correlation.
S-3 = S2QSO systems with measure equivalent widths and which have at
least three absorption lines detected above 3σ.
In principle, the SQSO3 sample comprises Lyman limit systems
(LLSs), sub-DLAs (i.e., absorbers with HI column densities,
log N(HI)≤20.30), DLAs, ghostly absorbers, and some false-positive
detections.
S-4 = S3QSO systems without spectra in which a DLA absorption is present.
The SQSO4 sample contains LLSs with log N(HI)<19.0, ghostly
absorbers, and some false-positive detections.
S-5 = 1446 systems with the exclusion of most false-positive detections.
Ghost = "Gst": By visually inspecting all spectra from the SQSO5 sample,
we could identify 30 ghostly absorbers (see Table 1).
See Section 2.1.
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History:
From electronic version of the journal
References:
Fathivavsari et al. Paper I. 2018MNRAS.477.5625F 2018MNRAS.477.5625F Cat. J/MNRAS/477/5625
(End) Prepared by [AAS], Emmanuelle Perret [CDs] 21-Jun-2021