J/ApJ/805/122 X-ray properties of PHL1811 analogs and WLQs (Luo+, 2015)
X-ray insights into the nature of PHL 1811 analogs and weak emission-line
quasars: unification with a geometrically thick accretion disk?
Luo B., Brandt W.N., Hall P.B., Wu J., Anderson S.F., Garmire G.P.,
Gibson R.R., Plotkin R.M., Richards G.T., Schneider D.P., Shemmer O.,
Shen Y.
<Astrophys. J., 805, 122 (2015)>
=2015ApJ...805..122L 2015ApJ...805..122L (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; QSOs ; Redshifts
Keywords: accretion, accretion disks; galaxies: active; galaxies: nuclei;
quasars: emission lines; X-rays: galaxies
Abstract:
We present an X-ray and multiwavelength study of 33 weak emission-line
quasars (WLQs) and 18 quasars that are analogs of the extreme WLQ,
PHL1811, at z∼0.5-2.9. New Chandra 1.5-9.5ks exploratory observations
were obtained for 32 objects while the others have archival X-ray
observations. Significant fractions of these luminous type 1 quasars
are distinctly X-ray weak compared to typical quasars, including 16
(48%) of the WLQs and 17 (94%) of the PHL 1811 analogs with average
X-ray weakness factors of 17 and 39, respectively. We measure a
relatively hard (Γ=1.16+0.37-0.32) effective power-law
photon index for a stack of the X-ray weak subsample, suggesting X-ray
absorption, and spectral analysis of one PHL 1811 analog, J1521+5202,
also indicates significant intrinsic X-ray absorption. We compare
composite Sloan Digital Sky Survey spectra for the X-ray weak and
X-ray normal populations and find several optical-UV tracers of X-ray
weakness, e.g., FeII rest-frame equivalent width (REW) and relative
color. We describe how orientation effects under our previously
proposed "shielding-gas" scenario can likely unify the X-ray weak and
X-ray normal populations. We suggest that the shielding gas may
naturally be understood as a geometrically thick inner accretion disk
that shields the broad line region from the ionizing continuum. If
WLQs and PHL 1811 analogs have very high Eddington ratios, the inner
disk could be significantly puffed up (e.g., a slim disk). Shielding
of the broad emission-line region by a geometrically thick disk may
have a significant role in setting the broad distributions of CIV REW
and blueshift for quasars more generally.
Description:
The selected SDSS-DR7 quasars were observed in Chandra Cycle 14 with
3.7-9.5ks exposures (Table 1) using the S3 CCD of the Advanced CCD
Imaging Spectrometer (ACIS). In addition, we obtained a 40ks Chandra
exposure of J1521+5202 that had a previous 4ks Chandra exposure (Just
et al. 2007ApJ...665.1004J 2007ApJ...665.1004J) and was studied as a PHL 1811 analog in
W11 (Wu et al. 2011ApJ...736...28W 2011ApJ...736...28W).
Our weak-line quasars (WLQ) targets were mainly selected from Plotkin
et al. (2010, J/AJ/139/390). They were observed in Chandra Cycle 14
with 1.5-3.5ks exposures using the ACIS-S3 CCD (Table 1).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 134 34 New Chandra observations and X-ray photometric
properties
table5.dat 44 51 Bolometric luminosity, supermassive black hole
(SMBH) mass, and Eddington ratio estimates
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See also:
VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/149/203 : Reddening of ∼35000 quasars from SDSS (Krawczyk+, 2015)
J/A+A/570/A96 : GTC spectra of z∼2.3 quasars (Sulentic+, 2014)
J/A+A/568/A114 : SDSS quasars with weak emission lines (Meusinger+, 2014)
J/ApJS/213/26 : Optical light curves of PHL1811 and 3C273 (Fan+, 2014)
J/ApJS/206/4 : SED & bolometric corrections for QSOs (Krawczyk+, 2013)
J/ApJ/757/51 : FIRST-2MASS dust-reddened QSO spectra (Glikman+, 2012)
J/ApJ/756/52 : R-band light curve of QSO J0158-4325 images (Morgan+, 2012)
J/ApJ/747/10 : X-ray and multiwavelength properties of 11 WLQs (Wu+, 2012)
J/ApJ/746/169 : Luminosity function of broad-line quasars (Shen+, 2012)
J/ApJ/746/54 : Chandra X-ray observations of SDSS-DR5 QSOs (Gibson+, 2012)
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJS/194/42 : SDSS-DR3 MgII-based black hole masses (Rafiee+, 2011)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/A+A/512/A34 : XMM-COSMOS Type 1 AGNs (Lusso+, 2010)
J/AJ/139/390 : Optically selected BL Lac objects from SDSS (Plotkin+, 2010)
J/ApJ/699/782 : High-redshift SDSS-DR5 QSOs (Diamond-Stanic+, 2009)
J/ApJ/696/580 : Properties of weak emission-line QSOs (WLQ) (Shemmer+, 2009)
J/ApJ/685/773 : X-ray-UV relations in SDSS DR5 QSOs (Gibson+, 2008)
J/AJ/135/2453 : Sample of BL Lac objects from SDSS and FIRST (Plotkin+, 2008)
J/ApJS/169/353 : Chandra sources in M17 (Broos+, 2007)
J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)
J/AJ/129/2542 : BL Lac from SDSS (Collinge+, 2005)
J/AJ/122/503 : SDSS u*g*r*i*z* phot. and redshift of QSOs (Anderson+, 2001)
J/AJ/121/2308 : Sloan Digital Sky Survey quasar photometry (Richards+, 2001)
http://www.sdss.org/ : SDSS home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Set Object type (p=PHL1811 analogs;
w=weak-line quasars (WLQs))
3- 20 A18 --- Name Object name (HHMMSS.ss+DDMMSS.s; J2000)
22 A1 --- f_Name a: included in this table but not in
figures or our analyses (see section 2.2)
24- 28 F5.3 --- z [0.4/3] Redshift
30- 34 I5 --- obsID Chandra observation ID number
36- 46 A11 "YYYY/MMM/DD" Date Observation start date
48- 51 F4.1 ks Exp [1.5/37.1] Background-flare cleaned
effective exposure time in the 0.5-8keV
band
53 A1 --- l_Scts Limit flag on Scts (1)
55- 58 F4.1 ct Scts [2/51.2] Aperture-corrected source
counts in the soft (0.5-2keV) band
60- 62 F3.1 ct e_Scts [1.3/7.3]? Negative error on Scts
64- 66 F3.1 ct E_Scts [2.7/8.4]? Positive error on Scts
68 A1 --- l_Hcts Limit flag on Hcts (1)
70- 73 F4.1 ct Hcts [2.1/47.9] Aperture-corrected source
counts in the hard (2-8keV) band
75- 77 F3.1 ct e_Hcts [1.4/7.3]? Negative error on Hcts
79- 81 F3.1 ct E_Hcts [2.9/8.5]? Positive error on Hcts
83 A1 --- l_HR Limit flag on HR
85- 88 F4.2 --- HR [0.1/3.2]? Ratio between the soft-band
and hard-band counts (2)
90- 93 F4.2 --- e_HR [0.07/2.3]? Negative error on HR
95- 98 F4.2 --- E_HR [0.1/6.2]? Positive error on HR
100 A1 --- l_Gam Limit flag on Gam
102-105 F4.1 --- Gam [-0.3/2.2]? 0.5-8keV effective power-law
photon index (3)
107-109 F3.1 --- e_Gam [0.2/0.9]? Negative error on Gam
111-113 F3.1 --- E_Gam [0.2/1.3]? Positive error on Gam
115-134 A20 --- Comm Comment (W11=Wu et al.,
2011ApJ...736...28W 2011ApJ...736...28W)
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Note (1): An upper limit at a 90% confidence level is given if the source is
not detected.
Note (2): Blank entries indicate that the source is undetected in both bands.
Note (3): 0.5-8keV effective power-law photon index, derived from the band ratio
assuming a power-law spectrum modified with Galactic absorption.
Blank entries indicate that it cannot be constrained.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Source Observation or archive (1)
6 A1 --- set Object type (p=PHL1811 analogs;
w=weak-line quasars)
8- 25 A18 --- Name Object identifier (HHMMSS.ss+DDMMSS.s; J2000)
27- 30 F4.1 [10-7W] logL [45.3/48.2] Log bolometric luminosity; erg/s
32- 35 F4.1 [Msun] logM [-1/10]?=-1 Log black hole mass (2)
37- 38 I2 --- f_logM [-1/2] Flag on logM (3)
40- 44 F5.2 --- LEdd [-1/2.9]?=-1 Eddington ratio estimate (2)
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Note (1): Code as follows:
CC14 = Chandra Cycle 14 (see Table 1 and the "Description" section above)
W11 = Wu et al., 2011ApJ...736...28W 2011ApJ...736...28W
W12 = Wu et al., 2012, J/ApJ/747/10
Note (2): We caution that the SMBH mass and bolometric luminosity estimates
have substantial uncertainties (see Sections 5.3 and 4.2), and thus
so do the Eddington ratios.
Note (3): Flag as follows:
-1 = Black hole mass not available;
1 = Mg II-based single epoch virial black hole mass
from Shen et al. (2011);
2 = Hβ-based virial black hole mass from Wu et al. (2011)
or Plotkin et al. (2015).
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Emmanuelle Perret [CDS] 15-Sep-2015