J/ApJ/843/30 MgII line vs 3000Å continuum analysis in 68 QSOs (Zhu+, 2017)
Relation between the variations in the MgIIλ2798 emission line and
3000Å continuum.
Zhu D., Sun M., Wang T.
<Astrophys. J., 843, 30 (2017)>
=2017ApJ...843...30Z 2017ApJ...843...30Z
ADC_Keywords: QSOs ; Spectra, optical ; Equivalent widths ; Redshifts
Keywords: black hole physics; galaxies: active; quasars: emission lines;
quasars: general ; surveys
Abstract:
We investigate the relationship between the MgIIλ2798 emission
line and the 3000Å continuum variations using a sample of 68
intermediate-redshift (z∼0.65-1.50) broad-line quasars spanning a
bolometric luminosity range of 44.49erg/s≤logLbol≤46.31erg/s
(Eddington ratio from ∼0.026 to 0.862). This sample is constructed
from SDSS-DR7Q and BOSS-DR12Q, each with at least two spectroscopic
epochs in SDSS-I/II/III surveys. In addition, we adopt the following
signal-to-noise ratio (S/N) selection criteria: (a) for MgII and the
3000Å continuum, S/N≥10; and (b) for narrow lines, S/N≥5. All our
quasar spectra are recalibrated based on the assumption of constant
narrow emission- line fluxes. In an analysis of spectrum-to-spectrum
variations, we find a fairly close correlation (Spearman ρ=0.593)
between the variations in broad MgII and in the continuum. This is
consistent with the idea that MgII is varying in response to the
continuum emission variations. Adopting the modified weighted least
squares regression method, we statistically constrain the slopes
(i.e., the responsivity α of the broad MgII) between the
variations in both components for the sources in different luminosity
bins after eliminating intrinsic biases introduced by the rescaling
process itself. It is shown that the responsivity is quite small
(average {bar}α∼0.464) and anti- correlates with the quasar
luminosity. Our results indicate that high signal- to-noise flux
measurements are required to robustly detect the intrinsic variability
and the time lag of the MgII line.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 2420 *Sample data
qsos.dat 24 69 List of unique quasars; table added by CDS
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Note on table1.dat: Table 1 summarizes part of the final 1210 data pairs,
consisting of 68 quasars that passed all the selection criteria and were
used for the analysis of the spectroscopic variations in the MgIIλ2798
emission line and in the 3000Å continuum.
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See also:
II/282 : The SDSS Photometric Catalog, Release 6 (Adelman-McCarthy+, 2007)
VI/64 : Recombination line intensities for hydrogenic ions (Storey+, 1995)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
J/ApJ/613/682 : AGN central masses & broad-line region sizes (Peterson+, 2004)
J/ApJ/633/638 : Variable quasar sample from SDSS (Wilhite+, 2005)
J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)
J/ApJ/705/L76 : AGNs with double-peaked [OIII] lines (Wang+, 2009)
J/ApJ/708/427 : Type 2 AGNs with double-peaked [OIII] lines (Liu+, 2010)
J/ApJ/732/121 : V-band and Hβ monitoring of Z299-15 (Barth+, 2011)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/755/60 : Reverberation mapping for 5 Seyfert 1 galaxies (Grier+, 2012)
J/ApJ/753/125 : NIR spectroscopy follow-up of 60 SDSS-DR7 QSOs (Shen+, 2012)
J/ApJ/818/30 : Lag measurements for z<0.8 QSOs from the SDSS-RM (Shen+, 2016)
Byte-by-byte Description of file: qsos.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- SDSS SDSS object name (JHHMMSS.ss+DDMMSS.s)
21- 24 F4.2 --- z [0.6/1.5] Improved quasar redshift from SDSS DR7Q
and DR12Q (as in table 1)
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- ID Identification number of our data pairs
in this paper
6- 24 A19 --- SDSS SDSS object name (JHHMMSS.ss+DDMMSS.s)
26- 29 I4 --- Plate SDSS Plate number
31- 34 I4 --- Fiber SDSS Fiber number
36- 40 I5 d MJD Modified Julian Date of observation
42- 47 F6.2 --- EW [18.4/195.5] Broad Mg II equivalent width (1)
49- 53 F5.2 [10-7W] logMg2 [36.8/42.5] log narrow MgII line luminosity (2)
55- 59 F5.2 [10-7W] logNe4 [0/42.3] log Ne IV (3426Å) line luminosity (2)
61- 65 F5.2 [10-7W] logO2 [40.4/45.1] log O II (3726, 3729Å)
line luminosity (2)
67- 71 F5.2 [10-7W] logNe3 [40.4/42.4] log NeIII (3869Å) line
luminosity (2)
73- 77 F5.2 [10-7W] logO3 [0/43.4] log OIII (5008Å) line luminosity (2)
79- 82 F4.2 --- z [0.6/1.5] Improved quasar redshift from DR7Q
and DR12Q
84- 88 F5.2 [10-7W] log3000 [43.7/45.7] log 3000Å continuum luminosity (2)
90- 94 A5 --- Cat Quasar catalog observation is included in
96 I1 --- Nr [1/5] Number or narrow-lines used in final
flux recalibration
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Note (1): relative to the underlying continuum at 3000Å.
Note (2): In units of erg/s.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Feb-2018