J/A+A/631/A150 Softly X-raying the gamma-ray sky I. (Marchesini+, 2019)
The gamma-ray sky seen at X-ray energies. I. Searching for the connection
between X-rays and gamma-rays in Fermi BL Lac objects.
Marchesini E.J., Paggi A., Massaro F., Masetti N., D'Abrusco R.,
Andruchow I., de Menezes R.
<Astron. Astrophys. 631, A150 (2019)>
=2019A&A...631A.150M 2019A&A...631A.150M (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; X-ray sources ; Gamma rays ; Photometry, infrared
Keywords: (galaxies:) BL Lacertae objects: general - X-rays: galaxies -
Gamma rays: galaxies - galaxies: active - galaxies: jets
Abstract:
BL Lac objects are an extreme type of active galactic nuclei (AGNs)
that belong to the largest population of gamma-ray sources: blazars.
This class of AGNs shows a double-bumped spectral energy distribution
that is commonly described in terms of a synchrotron self-Compton
(SSC) emission process, whereas the low-energy component that
dominates their emission between the infrared and the X-ray band is
tightly connected to the high-energy component that peaks in the
gamma-rays. Two strong connections that link radio and mid-infrared
emission of blazars to the emission in the gamma-ray band are well
established. They constitute the basis for associating gamma-ray
sources with their low-energy counterparts.
We searched for a possible link between X-ray and gamma-ray emissions
for the subclass of BL Lacs using all archival Swift/XRT observations
combined with Fermi data for a selected sample of 351 sources.
Analyzing ∼2400ks of Swift/XRT observations that were carried out
until December 2018, we discovered that above the gamma-ray flux
threshold Fgamma~=3x10-12erg/cm2/s, 96% of all Fermi BL Lacs have
an X-ray counterpart that is detected with signal-to-noise ratio >3.
We did not find any correlation or clear trend between X-ray and
gamma-ray fluxes and/or spectral shapes, but we discovered a
correlation between the X-ray flux and the mid-infrared color.
Finally, we discuss on a possible interpretation of our results in the
SSC framework.
Description:
Main results of our analysis. In column 1 we report the source name as
listed in BZCat, in columns 2 and 3 the total counts and their error
for the soft (0.5-2.0keV) and hard (2.0-10keV) bands, in column 4
the total band (0.5-10keV) flux and its uncertainty, in erg/cm2/s
units, in columns 5 to 10 the AllWISE magnitudes and their
uncertainties for each source, and in column 11 the X-ray to radio
flux ratio. The AllWISE magnitudes W1, W2 and W3 correspond to
wavelengths 3.4, 4.6, and 12 microns, respectively. Sources with
pile-up are marked with a dagger next to their name.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 334 Main results of our analysis
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See also:
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Source BZCat source name (5BZB JHHMM+DDMM)
17- 24 F8.3 ph CSoft Total counts in soft (0.5-2.0keV) band
26- 30 F5.1 ph e_CSoft rms uncertainty in CSoft
32- 40 F9.4 ph CHard Total counts in hard (2.0-10keV) band
42- 47 F6.3 ph e_CHard rms uncertainty in CHard
49- 52 F4.1 10-15W/m2 Flux Flux in total band (0.5-10keV)
54- 55 F2.1 10-15W/m2 e_Flux rms uncertainty in Flux
57- 62 F6.3 mag W1mag ?=- Wise W1 (3.4um) magnitude
64- 68 F5.3 mag e_W1mag ?=- rms uncertainty in W1mag
70- 75 F6.3 mag W2mag ?=- Wise W2 (4.6um) magnitude
77- 81 F5.3 mag e_W2mag ?=- rms uncertainty in W2mag
83- 88 F6.3 mag W3mag ?=- Wise W3 (12um) magnitude
90- 94 F5.3 mag e_W3mag ?=- rms uncertainty in W3mag
96-101 F6.1 10-12 FX/S1.4 ? X-ray to 1.4GHz flux ratio
102 A1 --- u_FX/S1.4 [?] Uncertainty flag on FX/S1.4
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Acknowledgements:
Ezequiel Joaquin Marchesini, ejmarchesini(at)gmail.com
(End) Patricia Vannier [CDS] 13-Sep-2019