J/MNRAS/458/56 TeV gamma-ray blazar X-ray spectral studies (Wierzcholska+, 2016)
X-ray spectral studies of TeV gamma-ray emitting blazars.
Wierzcholska A., Wagner S.J.
<Mon. Not. R. Astron. Soc., 458, 56-83 (2016)>
=2016MNRAS.458...56W 2016MNRAS.458...56W (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; Gamma rays ; X-ray sources ; Redshifts
Keywords: radiation mechanisms: non-thermal - galaxies: active -
BL Lacertae objects: general - galaxies: jets
Abstract:
This work is a summary of the X-ray spectral studies of 29TeV
(1012eV, tera-electron-volt) γ-ray emitting blazars observed
with Swift/XRT, especially focusing on sources for which the X-ray
regime allows us to study the low- and the high-energy ends of the
particle distribution function. Variability studies require
simultaneous coverage, ideally sampling different flux states of each
source. This is achieved using X-ray observations by disentangling the
high-energy end of the synchrotron emission and the low-energy end of
the Compton emission, which are produced by the same electron
population. We focused on a sample of 29 TeV γ-ray emitting
blazars with the best signal-to-noise X-ray observations collected
with Swift/XRT in the energy range 0.3-10keV during 10yr of
Swift/XRT operations. We investigate the X-ray spectral shapes and the
effects of different corrections for neutral hydrogen absorption and
decompose the synchrotron and inverse Compton components. For five
sources (3C 66A, S5 0716+714, W Comae, 4C +21.35 and BL Lacertae) a
superposition of both components is observed in the X-ray band,
permitting simultaneous, time-resolved studies of both ends of the
electron distribution. The analysis of multi-epoch observations
revealed that the break energy of the X-ray spectrum varies only by a
small factor with flux changes. Flux variability is more pronounced in
the synchrotron domain (high-energy end of the electron distribution)
than in the Compton domain (low-energy end of the electron
distribution). The spectral shape of the Compton domain is stable,
while the flux of the synchrotron domain is variable. These changes
cannot be described by simple variations of the cut-off energy,
suggesting that the high-energy end of the electron distribution is
not generally well described by cooling only.
Description:
The catalogue of TeV sources (TeVCat, http://tevcat.uchicago.edu)
includes 161 objects and 58 of them are classified as blazars. All of
the blazars have been observed several times with Swift/XRT. The main
properties of the TeV blazars, as well as the total exposure in the PC
mode and integrated flux for the energy range 0.3-10keV obtained using
the online analysis of Swift/XRT data (Evans et al., 2009, Cat.
J/MNRAS/397/1177), are collected in Table 1.
For the 29 selected blazars, the Swift/XRT data were analysed using
HEASoft package v. 6.16 software with CALDB v. 20140120.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 145 59 Summary of tera-electron-volt blazars
refs.dat 157 91 References
table2.dat 79 58 Comparison of Galactic column density values
table3.dat 63 116 Fit parameters for the log-parabola fits
for 29 sources
table4.dat 67 116 Fit parameters for power-law fits
for 29 sources
table5.dat 76 20 Fit parameters for broken power-law fits
for 5 sources
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See also:
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- Name Object name
23- 24 A2 --- r_Name TeV detection reference, in refs.dat file
26- 27 I2 h RAh Right ascension (J2000)
29- 30 I2 min RAm Right ascension (J2000)
32- 35 F4.1 s RAs Right ascension (J2000)
37 A1 --- DE- Declination sign (J2000)
38- 39 I2 deg DEd Declination (J2000)
41- 42 I2 arcmin DEm Declination (J2000)
44- 45 I2 arcsec DEs Declination (J2000)
47- 50 A4 --- Type Type of blazar
52 A1 --- l_z Limit flag on z
53- 58 F6.4 --- z ?=9.999 Redshift
59- 60 A2 --- r_z Redshift reference, in refs.dat file
62- 67 F6.2 10-15W/m2 FPC ? Integrated flux for Swift/XRT
observations in PC mode in the energy range
0.3-10keV
69- 73 F5.1 ks ExpPC ? Exposure for Swift/XRT observations in PC
mode in the energy range 0.3-10keV
75- 79 F5.2 10-18W/cm2 FPCxExpPC ? Product FPC and ExpPC (in 10-11erg/cm2)
81 A1 --- Flag [+] + for blazars selected for further
detailed studies
83-145 A63 --- Note Note
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Ref Reference code
4- 22 A19 --- BibCode BibCode
24- 60 A37 --- Aut Author's name
62-157 A96 --- Com Comments
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Name Object Name
24- 28 F5.2 10+20cm-2 NHLAB NH value provided by Kalberla et al.
(2005A&A...440..775K 2005A&A...440..775K, Cat. VIII/76)
30- 34 F5.2 10+20cm-2 NHDL NH value provided by Dickey & Lockman
(1990ARA&A..28..215D 1990ARA&A..28..215D)
36- 40 F5.2 10+20cm-2 NHH2 NH2 value provided by Willingale et al.
(2013MNRAS.431..394W 2013MNRAS.431..394W)
42- 46 F5.2 10+20cm-2 NHWill NH value provided by Willingale13
48- 52 F5.2 10+20cm-2 NHLPFree ?=- Free NH value obtained with
log-parabola model fitted
54- 57 F4.2 10+20cm-2 e_NHLPFree ?=- rms uncertainty on NHLPFree
59- 63 F5.2 10+20cm-2 NHPLFree ?=- Free NH value obtained with
power-law model fitted
65- 68 F4.2 10+20cm-2 e_NHPLFree ?=- rms uncertainty on NHPLFree
70- 74 F5.2 10+20cm-2 NHBPFree ?=- Free NH value obtained with
broken power-law model fitted
76- 79 F4.2 10+20cm-2 e_NHBPFree ?=- rms uncertainty on NHBPFree
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Object name
17- 20 A4 --- Ref Source of NH value (G1)
22- 25 F4.2 --- alpha α parameter
27- 30 F4.2 --- e_alpha rms uncertainty on alpha
32- 36 F5.2 --- beta β parameter
38- 41 F4.2 --- e_beta rms uncertainty on beta
43- 47 F5.3 10-2/cm2/s/keV Nl Normalization for the log-parabola fit
defined in Section 3
49- 53 F5.3 10-2/cm2/s/keV e_Nl rms uncertainty on Nl
55- 59 F5.3 --- rchi2 Reduced χ2 value
60 A1 --- --- [/]
61- 63 I3 --- DOF Number of degrees of freedom
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Object name
17- 20 A4 --- Ref Source of NH value (G1)
22- 25 F4.2 --- GAMMA Spectral index
27- 30 F4.2 --- e_GAMMA rms uncertainty on GAMMA
32- 36 F5.3 10-2/cm2/s/keV Np Normalization for the power-law fit
defined in Sect.3
38- 42 F5.3 10-2/cm2/s/keV e_Np rms uncertainty on Np
44- 48 F5.3 --- rchi2 Reduced χ2 value
50- 52 I3 --- DOF Number of degrees of freedom
54- 58 F5.1 --- F Test statistics value for F-test
60- 64 E5.2 --- pvalue Probability
66- 67 A2 --- Model Preferable model (1)
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Note (1): Preferable model as follows:
PO = power-law
LP = log-parabola model
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Object name
15- 18 A4 --- Ref Source of NH value (G1)
20- 24 F5.3 --- GAMMA1 First spectral index
26- 30 F5.3 --- e_GAMMA1 rms uncertainty on GAMMA1
32- 36 F5.3 --- GAMMA2 Second spectral index
38- 42 F5.3 --- e_GAMMA2 rms uncertainty on GAMMA2
44- 48 F5.3 10-2/cm2/s/keV Nb Normalization for the power-law fit
defined in Sect.3
50- 54 F5.3 10-2/cm2/s/keV e_Nb rms uncertainty on Nb
56- 60 F5.3 keV Eb Break energy for the broken power-law
fit defined in Sect. 3
62- 66 F5.3 keV e_Eb rms uncertainty on Eb
68- 72 F5.3 --- rchi2 Reduced χ2 value
74- 76 I3 --- DOF Number of degrees of freedom
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Global notes:
Note (G1):
Source of NH value as follows:
LAB = Kalberla et al. (2005A&A...440..775K 2005A&A...440..775K, Cat. VIII/76)
DL = Dickey & Lockman (1990ARA&A..28..215D 1990ARA&A..28..215D)
Will = Willingale et al. (2013MNRAS.431..394W 2013MNRAS.431..394W)
Free = free NH value
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Nov-2016