J/ApJ/747/10 X-ray and multiwavelength properties of 11 WLQs (Wu+, 2012)
X-ray and multiwavelength insights into the nature of weak emission-line quasars
at low redshift.
Wu J., Brandt W.N., Anderson S.F., Diamond-Stanic A.M., Hall P.B.,
Plotkin R.M., Schneider D.P., Shemmer O.
<Astrophys. J., 747, 10 (2012)>
=2012ApJ...747...10W 2012ApJ...747...10W
ADC_Keywords: QSOs ; Redshifts ; BL Lac objects ; X-ray sources ; Ultraviolet ;
Equivalent widths
Keywords: BL Lacertae objects: general - galaxies: active - galaxies: nuclei -
quasars: emission lines - X-rays: galaxies
Abstract:
We report on the X-ray and multiwavelength properties of 11
radio-quiet quasars with weak or no emission lines identified by the
Sloan Digital Sky Survey (SDSS) with redshift z=0.4-2.5. Our sample
was selected from the Plotkin et al. catalog (2010, Cat. J/AJ/139/390)
of radio-quiet, weak-featured active galactic nuclei (AGNs). The
distribution of relative X-ray brightness for our low-redshift
weak-line quasar (WLQ) candidates is significantly different from that
of typical radio-quiet quasars, having an excess of X-ray weak
sources, but it is consistent with that of high-redshift WLQs. Over
half of the low-redshift WLQ candidates are X-ray weak by a factor of
≳5, compared to a typical SDSS quasar with similar UV/optical
luminosity. These X-ray weak sources generally show similar UV
emission-line properties to those of the X-ray weak quasar PHL 1811
(weak and blueshifted high-ionization lines, weak semiforbidden lines,
and strong UV Fe emission); they may belong to the notable class of
PHL 1811 analogs. The average X-ray spectrum of these sources is
somewhat harder than that of typical radio-quiet quasars.
Description:
We have compiled a sample of 11 radio-quiet weak-line quasar (WLQ)
candidates with z=0.4-2.5 and presented their X-ray and
multiwavelength properties. These sources are mainly selected from the
catalog of radio-quiet, weak-featured SDSS quasars in Plotkin et al.
(2010, Cat. J/AJ/139/390). Six of them were observed in new
Chandra/ACIS Cycle 12 observations, while five have archival Chandra
or XMM-Newton coverage.
To obtain accurate measurements of the weak emission lines, we
manually measured rest-frame emission-line properties for CIV, SiIV,
the λ1900 complex, and FeIII UV48 (see Table 2) following the
method in Section 2.2 of Wu et al. (2011ApJ...736...28W 2011ApJ...736...28W).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 12 X-Ray observation log
table2.dat 95 14 Quasar UV emission-line measurements
table3.dat 120 105783 Continuum S/N values for SDSS DR7 quasars
table4.dat 109 12 X-Ray counts and basic spectral properties
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2013)
B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
VII/269 : SDSS Quasar Catalog, DR9Q (Paris+, 2012)
J/ApJS/206/4 : SED for luminous QSOs (Krawczyk+, 2013)
J/ApJ/746/54 : Chandra X-ray observations of SDSS-DR5 QSOs (Gibson+, 2012)
J/ApJ/726/20 : X-ray emission from quasars (Miller+, 2011)
J/AJ/139/390 : SDSS-DR7 optically selected BL Lac objects (Plotkin+, 2010)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
J/ApJ/702/767 : CIV and FeKα Baldwin effects in AGNs (Wu+, 2009)
J/ApJ/696/580 : Properties of weak emission-line QSOs (WLQ) (Shemmer+, 2009)
J/ApJ/699/782 : High-redshift SDSS-DR5 QSOs (Diamond-Stanic+, 2009)
J/ApJ/692/758 : BAL QSOs in SDSS-DR5 (Gibson+, 2009)
J/ApJS/183/17 : The SDSS DR5/XMM-Newton quasar survey (Young+, 2009)
J/A+A/434/475 : Redshifts for X-ray selected AGNs (Kitsionas+, 2005)
J/AJ/129/2542 : BL Lac from SDSS (Collinge+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Set [A/C] C=Chandra cycle 12 objects;
A=archival X-ray data objects
3- 20 A18 --- SDSS SDSS name (HHMMSS.ss+DDMMSS.s; J2000)
22- 26 F5.3 --- z [0.39/2.5] Redshift for each source (1)
28- 30 F3.1 arcsec dOX [0/1]? Angular distance between the optical
and X-ray positions;
no entry=no X-ray detection
32- 37 A6 --- Det Detector (ACIS-I, -S or MOS)
38 A1 --- f_Det [c] More than one detector (2)
40- 50 A11 "YYYY/MMM/DD" Date Observation date
52- 61 I10 --- ObsID Observation number
63- 66 F4.1 ks Exp [3/27] Exposure time
68- 70 F3.1 arcmin OA [0.3/6.4] Off-axis angle
72- 76 A5 --- Ref [,1-4] Reference(s) number (3)
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Note (1): The redshift values for our low-redshift weak-line quasars (WLQs) are
generally those from Hewett & Wild (2010, Cat. J/MNRAS/405/2302). For
two quasars (J1109+3736 and J1139-0201), the redshift values are taken
from the catalog of Plotkin et al. (2010, Cat. J/AJ/139/390). The
redshift of the other source (J2115+0001; z=2.4995±0.0052) is
measured based on a Lyα+CIV absorption system (See section 3.1).
Note (2): This object was observed by both the MOS and pn detectors. We list
MOS detector parameters here.
Note (3): Reference as follows:
1 = Plotkin et al. 2010, Cat. J/AJ/139/390;
2 = Hryniewicz et al. 2010MNRAS.404.2028H 2010MNRAS.404.2028H;
3 = Collinge et al. 2005, Cat. J/AJ/129/2542;
4 = Plotkin et al. 2010ApJ...721..562P 2010ApJ...721..562P.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Set [A/C] C=Chandra cycle 12 objects;
A=archival X-ray data objects
3- 20 A18 --- SDSS SDSS name (HHMMSS.ss+DDMMSS.s; J2000 except
for "PHL 1811" and "V01 composite")
22- 26 A5 --- Ref1 Origin of spectroscopic data (4)
28- 32 I5 d MJD [52051/55702]? Modified Julian day
34- 38 I5 km/s s(CIV) [-7300/-570]? CIV blueshift
40- 43 I4 km/s e_s(CIV) [30/1700]? s(CIV) uncertainty
45 A1 --- l_W(CIV) Limit flag on W(CIV)
47- 50 F4.1 0.1nm W(CIV) [3/30]? CIV rest equivalent width
52- 54 F3.1 0.1nm e_W(CIV) [0.3/2.7]? W(CIV) uncertainty
56 A1 --- l_W(SiIV) Limit flag on W(SiIV)
58- 60 F3.1 0.1nm W(SiIV) [4.8/9.9]? SiIV rest equivalent width (5)
62- 64 F3.1 0.1nm e_W(SiIV) [0.3/2.1]? W(SiIV) uncertainty (5)
66 A1 --- l_W(190) Limit flag on W(190)
68- 71 F4.1 0.1nm W(190) [1.9/21.7]? 1900Å rest equivalent width (6)
73- 75 F3.1 0.1nm e_W(190) [0.2/2.1]? W(190) uncertainty (6)
77 A1 --- l_W(FeIII) Limit flag on W(FEIII)
79- 81 F3.1 0.1nm W(FeIII) [1.7/9]? FeIII rest equivalent width
83- 85 F3.1 0.1nm e_W(FeIII) [0.1/1.5]? W(FeIII) uncertainty
87- 91 F5.2 0.1nm W(MgII) [5.8/17.1]? MgII rest equivalent width
93- 95 F3.1 0.1nm e_W(MgII) [0.4/1.1]? W(MgII) uncertainty
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Note (4): Flag as follows:
c = These measurements are taken from Wu et al. (2011ApJ...736...28W 2011ApJ...736...28W).
d = The composite spectrum from Vanden Berk et al. (2001AJ....122..549V 2001AJ....122..549V).
Note (5): This line is a blend of SiIV and OIV]; we refer to it as SiIV
simply for convenience.
Note (6): Mainly CIII]λ1909, but also including [NeIII]λ1814,
SiIIλ1816, AlIIIλ1857, SiIII]λ1892, and several
FeIII multiplets (see Table 2 of Vanden Berk et al. 2001AJ....122..549V 2001AJ....122..549V).
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Byte-by-byte Description of file: table3.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)
21- 25 F5.2 mag imag [0/22.36] The apparent i-band magnitude (1)
28- 32 F5.3 --- z [0.06/5.47] Redshift (2)
35- 39 I5 d MJD Modified Julian Day
41- 44 I4 --- Plate Plate number
46- 48 I3 --- Fiber Fiber number
52- 56 F5.2 --- SN170 [0/85]?=0 Signal-to-noise ratio at 1650-1750A (3)
59- 61 I3 --- Np170 Number of pixels at 1650-1750 A (4)
64- 67 I4 0.1nm 1700l ?=0 Wavelength lower limit; in Angstroms (5)
69- 72 I4 0.1nm 1700u [3788/9256]?=0 Wavelength upper limit; in Å (6)
76- 80 F5.2 --- SN300 [0/77]?=0 Signal-to-noise ratio at 2950-3050A (3)
83- 85 I3 --- Np300 Number of pixels at 2950-3050 A (4)
88- 91 I4 0.1nm 3000l ?=0 Wavelength lower limit; in Angstroms (5)
93- 96 I4 0.1nm 3000u [3796/9270]?=0 Wavelength upper limit; in Å (6)
100-104 F5.2 --- SN515 [0/82]?=0 Signal-to-noise ratio at 5100-5200 A (3)
107-109 I3 --- Np515 Number of pixels at 2950-3050 A (4)
112-115 I4 0.1nm 5150l ?=0 Wavelength lower limit; in Angstroms (5)
117-120 I4 0.1nm 5150u [5535/9273]?=0 Wavelength upper limit; in Å (6)
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Note (1): The apparent i-band magnitude using the BEST photometry of the
SDSS DR7 quasar catalog (Cat. VII/260)
Note (2): The redshift value from the SDSS DR7 quasar catalog.
Note (3): Wavelength range in the rest frame.
Note (4): Number of pixels used in calculation.
Note (5): Lower limit of the observed-frame wavelength range in calculation.
Note (6): Upper limit of the observed-frame wavelength range in calculation.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Set [A/C] C=Chandra cycle 12 objects;
A=archival X-ray data objects
3- 20 A18 --- SDSS SDSS name (HHMMSS.ss+DDMMSS.s; J2000)
22 A1 --- l_Fct Limit flag on Fband
24- 28 F5.1 ct Fct [3.3/552.3] Full band (0.5-8keV) X-ray counts
30- 33 F4.1 ct E_Fct [3/24.5]? Positive error on Fct (5)
35- 38 F4.1 ct e_Fct [1.7/23.5]? Negative error on Fct (5)
40 A1 --- l_Sct Limit flag on Sct
42- 46 F5.1 ct Sct [3.1/406.4] Soft band (0.5-2keV) X-ray counts
48- 51 F4.1 ct E_Sct [3/21.2]? Positive error on Sct (5)
53- 56 F4.1 ct e_Sct [1.7/20.2]? Negative error on Sct (5)
58 A1 --- l_Hct Limit flag on Hct
60- 64 F5.1 ct Hct [2.1/145.8] Hard band (2-8keV) X-ray counts
66- 69 F4.1 ct E_Hct [2.7/13.1]? Positive error on Hct (5)
71- 74 F4.1 ct e_Hct [1.3/12.1]? Negative error on Hct (5)
76 A1 --- l_H/S Limit flag on H/S
78- 81 F4.2 --- H/S [0.2/2.25]? Band ratio (6)
83- 86 F4.2 --- E_H/S [0.04/0.81]? Positive error on H/S (6)
88- 91 F4.2 --- e_H/S [0.03/0.4]? Negative error on H/S (6)
93 A1 --- l_Gamma Limit flag on Gamma
95- 99 F5.2 --- Gamma [-0.01/2.21]? Effective power-law photon
index Γ (7)
101-104 F4.2 --- E_Gamma [0.09/1.31]? Positive error on Gamma
106-109 F4.2 --- e_Gamma [0.09/0.87]? Negative error on Gamma
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Note (5): Errors on the X-ray counts were calculated using Poisson statistics
corresponding to the 1σ significance level according to
Tables 1 and 2 of Gehrels (1986ApJ...303..336G 1986ApJ...303..336G).
Note (6): The band ratio is defined here as the number of hard-band counts
divided by the number of soft-band counts. The errors on the band
ratio correspond to the 1σ significance level and were
calculated using Equation (1.31) in Section 1.7.3 of Lyons
(1991pgda.book.....L 1991pgda.book.....L). The band ratios for all of the Chandra objects
observed in the same cycle can be directly compared with one another.
Note (7): The effective power-law photon indices were calculated using the
Chandra PIMMS tool (version 3.9k). The effect of the quantum
efficiency decay over time at low energies of the ACIS detector was
corrected for Chandra observed objects.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 23-Sep-2013