J/ApJ/789/135 Gamma-ray bright blazars spectrophotometry (Williamson+, 2014)
Comprehensive monitoring of gamma-ray bright blazars.
I. Statistical study of optical, X-ray, and gamma-ray spectral slopes.
Williamson K.E., Jorstad S.G., Marscher A.P., Larionov V.M., Smith P.S.,
Agudo I., Arkharov A.A., Blinov D.A., Casadio C., Efimova N.V., Gomez J.L.,
Hagen-Thorn V.A., Joshi M., Konstantinova T.S., Kopatskaya E.N.,
Larionova E.G., Larionova L.V., Malmrose M.P., McHardy I.M., Molina S.N.,
Morozova D.A., Schmidt G.D., Taylor B.W., Troitsky I.S.
<Astrophys. J., 789, 135 (2014)>
=2014ApJ...789..135W 2014ApJ...789..135W (SIMBAD/NED BibCode)
ADC_Keywords: Spectrophotometry ; X-ray sources ; Gamma rays ; Ultraviolet ;
Photometry, UBVRIJKLMNH ; BL Lac objects ; QSOs
Keywords: BL Lacertae objects: general - galaxies: active - galaxies: jets -
quasars: general
Abstract:
We present γ-ray, X-ray, ultraviolet, optical, and near-infrared
light curves of 33 γ-ray bright blazars over 4 years that we
have been monitoring since 2008 August with multiple optical,
ground-based telescopes and the Swift satellite, and augmented by data
from the Fermi Gamma-ray Space Telescope and other publicly available
data from Swift. The sample consists of 21 flat-spectrum radio quasars
(FSRQs) and 12 BL Lac objects (BL Lacs). We identify quiescent and
active states of the sources based on their γ-ray behavior. We
derive γ-ray, X-ray, and optical spectral indices,
αγ, αX, and αo, respectively
(Fν∝να), and construct spectral energy
distributions during quiescent and active states. We analyze the
relationships between different spectral indices, blazar classes, and
activity states. We find (1) significantly steeper γ-ray spectra
of FSRQs than for BL Lacs during quiescent states, but a flattening of
the spectra for FSRQs during active states while the BL Lacs show no
significant change; (2) a small difference of αX within each
class between states, with BL Lac X-ray spectra significantly steeper
than in FSRQs; (3) a highly peaked distribution of X-ray spectral
slopes of FSRQs at ∼ -0.60, but a very broad distribution of
αXof BL Lacs during active states; (4) flattening of the
optical spectra of FSRQs during quiescent states, but no statistically
significant change of αo of BL Lacs between states; and (5) a
positive correlation between optical and γ-ray spectral slopes
of BL Lacs, with similar values of the slopes. We discuss the findings
with respect to the relative prominence of different components of
high-energy and optical emission as the flux state changes.
Description:
Since 2007, we have been collecting multi-waveband fluxes,
polarization measurements, and radio images of blazars to provide the
data for understanding the physics of the jets (see, e.g., Marscher
2012, 1201.5402). This study includes 28 of the original 30
objects selected for the monitoring campaign, confirmed as γ-ray
sources by EGRET (Energetic γ-Ray Experiment Telescope) on the
Compton Gamma Ray Observatory, have an R-band brightness exceeding 18
mag (bright enough for optical polarization measurements at a 1-2 m
class optical telescope without needing excessive amounts of telescope
time), exceed 0.5 Jy at 43 GHz, and have a declination accessible to
the collaboration's observatories (> - 30°). Three additional BL Lacs
(1055+018, 1308+326, and 1749+096) and two FSRQs (3C345 and 3C446)
included in this analysis were among those added when they were
detected as γ-ray sources by the Fermi LAT (Abdo et al. 2009,
J/ApJ/700/597).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 33 Sources Analyzed
table4.dat 251 33 Weighted Mean Flux and Weighted Standard
Deviations
table7.dat 69 114 Epochs Selected For Study
table8.dat 102 114 Computed Spectral Indices
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See also:
III/157 : An Ultraviolet Atlas of Quasar and Blazar Spectra
(Kinney+, 1991)
J/A+AS/114/337 : CCD photometric observations of blazars (Jia Guibin+, 1995)
J/A+A/436/799 : X- and gamma-ray fluxes of γ-ray-loud blazars
(Fan+, 2005)
J/ApJS/175/97 : CGRaBS: survey of γ-ray blazar candidates
(Healey+, 2008)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJ/732/116 : IR spectra of γ-ray bright blazars (Malmrose+, 2011)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJ/761/125 : X and γ spectral indexes of Fermi blazars (Fan+, 2012)
J/MNRAS/439/690 : Optical/γ-ray variability in blazars (Hovatta+, 2014)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq Sequential number
4- 14 A11 --- Name Object identifier
16- 23 A8 --- AName Commonly used name
25- 36 A12 --- 2FGL Catalog Object's name as listed in the
2FGL catalog (1)
38- 42 F5.3 --- z Redshift (2)
43 A1 --- n_z [d?] Note on z (3)
45- 46 I2 h RAh Hour of Right Ascension (J2000) (4)
48- 49 I2 min RAm Minute of Right Ascension (J2000) (4)
51- 55 F5.2 s RAs Second of Right Ascension (J2000) (4)
57 A1 --- DE- Sign of the Declination (J2000) (4)
58- 59 I2 deg DEd Degree of Declination (J2000) (4)
61- 62 I2 arcmin DEm Arcminute of Declination (J2000) (4)
64- 67 F4.1 arcsec DEs Arcsecond of Declination (J2000) (4)
69- 74 A6 --- Class Object's optical classification (1)
76- 78 A3 --- SEDclass SED classification (1)
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Note (1): Ackermann et al. (2011, J/ApJ/743/171).
Note (2): Information taken from the NASA/IPAC Extragalactic Database
(http://nedwww.ipac.caltech.edu/).
Note (3): Note on redshift as follows :
d = Danforth et al. (2013ApJ...764...57D 2013ApJ...764...57D) set 0.2315 < z < 0.372 (99.7%).
? = uncertain
Note (4): Simbad resolver as reported in http://heasarc.gsfc.nasa.gov.
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Object identifier
14- 21 E8.2 ct/cm2/s Fgamma Mean Fermi Γ-ray flux; photons/s/cm2
23- 30 E8.2 ct/cm2/s e_Fgamma Weighted standard deviation of Fgamma
32- 35 I4 --- o_Fgamma Number of observations used for Fgamma
37- 44 E8.2 mW/m2 FX ? Mean Swift/XRT X-ray flux; erg/s/cm2
46- 53 E8.2 mW/m2 e_FX ? Weighted standard deviation of FX
55- 57 I3 --- o_FX Number of observations used for FX
59- 64 F6.3 mJy Fuvw2 ? Mean Swift/UVOT w2 band flux
66- 70 F5.3 mJy e_Fuvw2 ? Weighted standard deviation of Fuvw2
72- 74 I3 --- o_Fuvw2 Number of observations used for Fuvw2
76- 81 F6.3 mJy Fuvm2 ? Mean Swift/UVOT m2 band flux
83- 87 F5.3 mJy e_Fuvm2 ? Weighted standard deviation of Fuvm2
89- 91 I3 --- o_Fuvm2 Number of observations used for Fuvm2
93- 98 F6.3 mJy Fuvw1 ? Mean Swift/UVOT w1 band flux
100-104 F5.3 mJy e_Fuvw1 ? Weighted standard deviation of Fuvw1
106-108 I3 --- o_Fuvw1 Number of observations used for Fuvw1
110-114 F5.3 mJy FU ? Mean Johnson U band flux
116-120 F5.3 mJy e_FU ? Weighted standard deviation of FU
122-124 I3 --- o_FU Number of observations used for FU
126-131 F6.3 mJy FB Mean Johnson B band flux
133-137 F5.3 mJy e_FB Weighted standard deviation of FB
139-141 I3 --- o_FB Number of observations used for FB
143-148 F6.3 mJy FV ? Mean Johnson V band flux
150-154 F5.3 mJy e_FV ? Weighted standard deviation of FV
156-159 I4 --- o_FV Number of observations used for FV
161-166 F6.3 mJy FR Mean Johnson R band flux
168-173 F6.3 mJy e_FR Weighted standard deviation of FR
175-178 I4 --- o_FR Number of observations used for FR
180-185 F6.3 mJy FI ? Mean I band flux
187-192 F6.3 mJy e_FI ? Weighted standard deviation of FI
194-196 I3 --- o_FI Number of observations used for FI
198-203 F6.3 mJy FJ ? Mean J band flux
205-210 F6.3 mJy e_FJ ? Weighted standard deviation of FJ
212-214 I3 --- o_FJ ? Number of observations used for FJ
216-221 F6.3 mJy FH ? Mean H band flux
223-228 F6.3 mJy e_FH ? Weighted standard deviation of FH
230-232 I3 --- o_FH ? Number of observations used for FH
234-239 F6.3 mJy FK ? Mean K band flux
241-246 F6.3 mJy e_FK ? Weighted standard deviation of FK
248-251 I4 --- o_FK ? Number of observations used for FK
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Object identifier
14 I1 --- Num Epoch number
16- 23 F8.3 d RJD-Non Earliest RJD date within epoch of
non-gamma-ray observations
25- 29 F5.3 d Span Elapsed timespan of non-gamma-ray observations
31- 38 F8.3 d RJD-Obs RJD of Fermi observation, mid-bin
40- 43 F4.1 d Bin Fermi observation bin size
45 A1 --- G-Act Activity state code in gamma-rays (1)
47 A1 --- X-Act Activity state code in X-rays (1)
49 A1 --- W2-Act Activity state code in uvw2 (1)
51 A1 --- M2-Act Activity state code in uvm2 (1)
53 A1 --- W1-Act Activity state code in uvw1 (1)
55 A1 --- U-Act Activity state code in U band (1)
57 A1 --- B-Act Activity state code in B band (1)
59 A1 --- V-Act Activity state code in V band (1)
61 A1 --- R-Act Activity state code in R band (1)
63 A1 --- I-Act Activity state code in I band (1)
65 A1 --- J-Act Activity state code in J band (1)
67 A1 --- H-Act Activity state code in H band (1)
69 A1 --- K-Act Activity state code in K band (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows :
Q = Quiescent;
T = Transitory;
A = Active;
F = Flaring;
Blank = No data;
I = Insufficient number of observations to calculate a mean flux value.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Object identifier
14 I1 --- Num Epoch number
16- 23 F8.3 d RJD-Non Earliest RJD date within epoch of
non-gamma-ray observations
25- 30 F6.3 --- agamma Gamma-ray spectral index
32- 36 F5.3 --- e_agamma ? The 1σ uncertainty in agamma
38- 43 F6.3 --- aX ? X-ray spectral index
45- 49 F5.3 --- e_aX ? The 1σ uncertainty in aX
51- 56 F6.3 --- aO Optical spectral index
58- 62 F5.3 --- e_aO The 1σ uncertainty in aO
64- 65 I2 --- Npts Number of UV/Opt/NIR points used
67- 71 F5.3 --- StDev ? Standard deviation of the data
73- 78 F6.3 --- aOX ? X-ray/optical spectral index
80- 84 F5.3 --- e_aOX ? The 1σ uncertainty in aOX
86- 91 F6.3 --- aXgamma ? Gamma-ray/X-ray spectral index
93- 97 F5.3 --- e_aXgamma ? The 1σ uncertainty in aXgamma
99-102 A4 --- Band UV/Opt/NIR band used if no V-band data
available
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 10-Mar-2017