X-ray spectra, light curves and SEDs of blazars frequently observed by Swift

Journal
Date Issued
2021
Author(s)
Giommi, Paolo
•
•
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D'Elia, V.
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Barres de Almeida, U.
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Brandt, C. H.
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Pollock, A. M. T.
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Arneodo, F.
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Di Giovanni, A.
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Chang, Y. L.
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Civitarese, O.
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De Angelis, M.
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Leto, C.
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•
Ricard, N.
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Di Pippo, S.
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Middei, R.
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Penacchioni, A. V.
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Ruffini, R.
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Sahakyan, N.
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Israyelyan, D.
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Turriziani, S.
DOI
Abstract
Blazars research is one of the hot topics of contemporary extragalactic astrophysics. That is because these sources are the most abundant type of extragalactic γ-ray sources and are suspected to play a central role in multimessenger astrophysics. We have used Swift$\_$xrtproc, a tool to carry out an accurate spectral and photometric analysis of the Swift-XRT data of all blazars observed by Swift at least 50 times between December 2004 and the end of 2020. We present a database of X-ray spectra, best-fit parameter values, count rates and flux estimations in several energy bands of over 31 000 X-ray observations and single snapshots of 65 blazars. The results of the X-ray analysis have been combined with other multifrequency archival data to assemble the broad-band Spectral Energy Distributions (SEDs) and the long-term light curves of all sources in the sample. Our study shows that large X-ray luminosity variability on different time-scales is present in all objects. Spectral changes are also frequently observed with a 'harder-when-brighter' or 'softer-when-brighter' behaviour depending on the SED type of the blazars. The peak energy of the synchrotron component (νpeak) in the SED of HBL blazars, estimated from the log-parabolic shape of their X-ray spectra, also exhibits very large changes in the same source, spanning a range of over two orders of magnitude in Mrk421 and Mrk501, the objects with the best data sets in our sample.
Volume
507
Issue
4
Start page
5690
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2021MNRAS.507.5690G
Rights
open.access
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