J/MNRAS/505/1954 Properties and X-rays of RLQs and RQQs quasars (Zhu+, 2021)
The X-ray spectral and variability properties of typical radio-loud quasars.
Zhu S.F., Timlin J.D., Brandt W.N.
<Mon. Not. R. Astron. Soc., 1954-1971 (2021)>
=2021MNRAS.505.1954Z 2021MNRAS.505.1954Z (SIMBAD/NED BibCode)
ADC_Keywords: Black holes ; Active gal. nuclei ; QSOs ; Redshifts ; Photometry ;
Spectroscopy ; X-ray sources ; Ultraviolet ; Optical ;
Radio sources
Keywords: black hole physics - galaxies: jets - galaxies: nuclei -
quasars: general - X-rays: galaxies
Abstract:
We present X-ray spectral and long-term variability analyses of an
unbiased sample of 361 optically selected radio-loud quasars (RLQs)
utilizing sensitive serendipitous X-ray data from the Chandra and
XMM-Newton archives. The spectral and temporal properties of RLQs are
compared with those of radio-quiet quasars (RQQs) matched in L2500
Å and z. The median power-law photon index (γ) of RLQs is
1.84-0.01+0.01, which is close to that of matched RQQs
(1.90-0.01+0.02). No significant correlations between γ
and radio-loudness, Lx/Lx,rqq (the X-ray luminosity over that expected
from the Lx-Luv relation for RQQs), redshift, or Eddington ratio are
found for our RLQs. The stacked X-ray spectra of our RLQs show strong
iron-line emission and a possible Compton-reflection hump. The
intrinsic X-ray variability amplitude is ~= 40 per cent for RLQs on
time-scales of months-to-years in the rest frame, which is somewhat
smaller than for the matched RQQs (~= 60 per cent) on similar time-
scales, perhaps due to the larger black hole masses and lower
Eddington ratios in our RLQ sample. The X-ray spectral and variability
results for our RLQs generally support the idea that the X-ray
emission of typical RLQs is dominated by the disc/corona, as is also
indicated by a recent luminosity correlation study.
Description:
First, we construct a sample of RLQs based on Zhu et al.
(2020MNRAS.496..245Z 2020MNRAS.496..245Z, Cat. J/MNRAS/496/245). Archival Chandra,
XMM-Newton, and ROSAT observations are used to calculate the X-ray
luminosities of these optically selected quasars with the help of SDSS.
Only a small fraction of the RLQ sample is targeted by these X-ray
observations, therefore this sample is not significantly biased by the
target selection of these X-ray observations (e.g. Gibson & Brandt
2012ApJ...746...54G 2012ApJ...746...54G, Cat. J/ApJ/746/54). This RLQ sample also has
large fractions of X-ray detections and spectroscopic confirmations by
SDSS as tabulated in table1.dat.
Secondly, in order to investigate the X-ray temporal properties of
RLQs using multiple-epoch observations, we match the RLQ list with the
observation catalogues of Chandra and XMM-Newton. The matching results
is used for X-ray spectral studies and to investigate the X-ray
variability properties of RLQs. We apply data reduction processus on
Chandra and XMM-Newton science images (see section 2.2) giving us
Chandra/ACIS and XMM-Newton/EPIC spectra on which we can compute X-ray
energy fluxes and detection flux limit (see section 2.3) and thus
performing X-ray spectral fitting to get access to the power spectrum
spectral indices (see section 3). The X-ray properties results are
summarized in the table2.dat for RLQs quasars.
Hereafter, we construct same tables for RQQs in order to compare them
to our previous RLQs samples. We therefore extended the analysis of
Timlin et al. (2020MNRAS.498.4033T 2020MNRAS.498.4033T, Cat. J/MNRAS/498/4033) with the
help of the SDSS DR14Q (Paris et al. 2018A&A...613A..51P 2018A&A...613A..51P, Cat.
VII/286) following the selection method seen before, the tablea1.dat
contains the properties of the 606 RQQs optically selected. Note that
all observations data are consistently analysed in the same way as
described above (see section 2.2, 2.3 and 3). In total, we obtain 2341
serendipitous Chandra observations of the RQQs listed in the tablea2.dat.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 135 349 *The RLQ sample used in this paper
table2.dat 242 628 The sample of RLQ X-ray observations
tablea1.dat 53 606 *The RQQ sample used in this paper
tablea2.dat 235 2341 The sample of RQQ X-ray observations
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Note on table1.dat: Properties are taken from Zhu et al.
(2020MNRAS.496..245Z 2020MNRAS.496..245Z, Cat. J/MNRAS/496/245). Furthermore, we use
L2keV, L2500A, and L5GHz interchangeably with Lx, Luv, and Lradio to denote
the X-ray, optical/UV, and radio luminosities.
Note on tablea1.dat: Properties are taken from Timlin et al.
(2020MNRAS.498.4033T 2020MNRAS.498.4033T, Cat. J/MNRAS/498/4033).
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See also:
J/MNRAS/496/245 : Lx-Luv-Lradio relation in radio-loud quasars
(Zhu+, 2020)
J/MNRAS/498/4033 : Extreme quasar X-ray variability (Timlin+, 2020)
J/ApJ/726/20 : X-ray emission from quasars (Miller+, 2011)
VII/286 : SDSS quasar catalog, fourteenth data release (Paris+,2018)
IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+,2019)
IX/55 : XMM-Newton Serendipitous Source Catalogue 3XMM-DR8
(XMM-SSC, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS-DR14 designation
(HHMMSS.ss+DDMMSS.s) (Name) (G1)
20- 25 F6.4 --- z Redshift normally heliocentric (z)
27- 37 F11.8 mag imag The i-band magnitude (mi) (1)
39- 54 F16.13 [10-7W/Hz] logL2500A Logarithm of the rest-frame
monochromatic luminosity at 2500 Å
(logL2500A)
56- 71 F16.13 [10-7W/Hz] logL5GHz Logarithm of the rest-frame
monochromatic luminosity at 5GHz
(logL5GHz)
73- 79 F7.4 [10-7W/Hz] logL2keV Logarithm of the rest-frame
monochromatic luminosity at 2keV
(logL2keV)
81- 97 F17.14 [-] logR Logarithm of the radio loudness
parameter R (logR) (2)
99-116 F18.15 --- alphaR ? Radio spectral slope,
-d(Log F)/d(Log nu) (alphaR)
118-135 F18.15 [-] log(Lx/Lxrqq) Logarithm of X-ray luminosity ratio (3)
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Note (1): Magnitude in i' filter of Sloan Digital Sky Survey
(1996AJ....111.1748F 1996AJ....111.1748F).
Note (2): Miller et al. (2011ApJ...726...20M 2011ApJ...726...20M, Cat. J/ApJ/726/20)
use R*=L5GHz/L2500A to quantify radio-loudness, which can be converted
to R using logR=logR*-0.123.
Note (3): The L2kev divided by L2kevrqq predicted with the Lx-Luv relation
for RQQs (Zhu et al. 2020MNRAS.496..245Z 2020MNRAS.496..245Z, Cat. J/MNRAS/496/245).
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- SDSS SDSS-DR14 designation
SDSS J (HHMMSS.ss+DDMMSS.s) (Name) (G1)
20- 29 A10 --- ObsID Objet identifier (ObsID)
31- 46 F16.10 s Obs Observation start date (MJD)
48- 51 A4 --- Inst The instrument used for the observation,
ACIS for Chandra and pn/MOS1/MOS2 for
XMM-Newton observations (Inst) (G2)
53- 69 F17.13 [mW/m2] logfdet Logarithm of the detection flux limit in the
0.5-7 keV band at the position of the quasar
on the detector expressed in erg/cm2/s
(logfdet) (G3)
71- 89 F19.13 ct CTnet The net source counts (G4)
91-108 F18.14 --- S/N Signal to noise ratio,
S/N = net/sqrt(s+b/k2) (SNR)
110-126 F17.13 [mW/m2] logfx Logarithm of the energy flux in the
0.5-7 keV band if the the quasar is detected
expressed in erg/cm2/s (logfx) (G5)
128 I1 --- f_logfx [0 1] Detection flag in the X-ray observation,
takes 1 if it's the case 0 otherwise (xdet)
130-148 F19.15 --- gamma ? The power-law photon index derived from our
spectral fitting, it is not estimated
for non-detection cases(gamma)
150-168 F19.15 --- e_gamma ? Lower error on gamma (gammaLo)
170-188 F19.15 --- E_gamma ? Upper error on gamma (gammaHi)
190-206 F17.13 --- cstat The statistic number of the fit (cstat) (G6)
208-224 F17.13 --- Ecstat The expectation number of cstat (Ecstat) (G6)
226-242 F17.13 --- s_cstat The standard deviation of cstat (Scstat) (G6)
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- SDSS SDSS-DR14 designation source
(HHMMSS.ss+DDMMSS.s) (Name) (G1)
21- 28 F8.6 --- z Redshift normally heliocentric (z)
30- 36 F7.4 mag imag The i-band magnitude (mi)
38- 53 F16.13 [10-7W/Hz] logL2500A Logarithm of the rest-frame
monochromatic luminosity at 2500 Å
(logL2500A)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- SDSS SDSS-DR14 designation
(HHMMSS.ss+DDMMSS.s) (Name) (G1)
21- 25 A5 --- ObsID Objet identifier (ObsID)
27- 42 F16.10 s Obs Observation start date (MJD)
44- 47 A4 --- Inst The instrument used for the observation,
ACIS for Chandra observations (Inst) (G2)
49- 65 F17.13 [mW/m2] logfdet Logarithm of the detection flux limit
in the 0.5-7 keV band at the position of
the quasar on the detector expressed
in erg/cm2/s (logfdet) (G3)
67- 85 F19.14 ct CTnet The net source counts (G4)
87-103 F17.14 --- S/N Signal to noise ratio,
S/N = net/sqrt(s+b/k2) (SNR)
105-121 F17.13 [mW/m2] logfx ? Logarithm of the energy flux
in the 0.5-7 keV band if the the quasar, is
detected, expressed in erg/cm2/s
(logfx) (G5)
123 I1 --- f_logfx [0 1] Detection flag in the X-ray observation,
takes 1 if it's the case 0 otherwise (xdet)
125-142 F18.14 --- gamma ? The power-law photon index derived from our
spectral fitting it is not estimated for
cases of non-detection (gamma)
144-162 F19.15 --- e_gamma ? Lower error on gamma (gammaLo)
164-182 F19.15 --- E_gamma ? Upper error on gamma (gammaHi)
184-200 F17.13 --- cstat The statistic number of the fit (cstat) (G6)
202-218 F17.13 --- Ecstat The expectation number of cstat (Ecstat) (G6)
220-235 F16.13 --- s_cstat The standard deviation of cstat (Scstat) (G6)
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Global notes:
Note (G1): SDSS-DR14 quasar catalog Paris et al. 2018A&A...613A..51P 2018A&A...613A..51P,
Cat. VII/286.
Note (G2): Instrument used for the observation as follows:
acis = ACIS, The Chandra Source Catalog Evans et al.
2019yCat.9057....0E 2019yCat.9057....0E, Cat. IX/57.
pn = PN, XMM-Newton/EPIC serendipitous survey (3XMM-DR8)
Rosen et al. 2016A&A...590A...1R 2016A&A...590A...1R, Cat. IX/55.
mos1 = MOS1, XMM-Newton/EPIC serendipitous survey (3XMM-DR8)
Rosen et al. 2016A&A...590A...1R 2016A&A...590A...1R, Cat. IX/55.
mos2 = MOS2, XMM-Newton/EPIC serendipitous survey (3XMM-DR8)
Rosen et al. 2016A&A...590A...1R 2016A&A...590A...1R, Cat. IX/55.
Note (G3): We determined a limit value for fdet name cut off value
of fdet ≤ 3*E-14, thus logfdet ≤ log(3*E-14) = -13.5228
(see 2.3 section for more details).
Note (G4): The net source counts after subtracting expected background counts,
net = s - b/k, where k is the background-to-source area ratio.
Note (G5): If the quasar is not detected, the upper bound of the 90 per cent
confidence interval is given.
Note (G6): The goodness-of-fit of the spectral fitting, cstat/Ecstat/Scstat,
where cstat is the statistic of the fit, and Ecstat and Scstat are
the expectation and standard deviation of cstat, respectively
(Kaastra 2017A&A...605A..51K 2017A&A...605A..51K).
For example, if (cstat - Ecstat)/Scstat > 4, the fitting result is
disfavoured at a 4σ significance level.
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 29-May-2024