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

GIOMMI, P.; PERRI, M.; CAPALBI, M.; D'ELIA, V.; BARRES DE ALMEIDA, U.; BRANDT, C.H.; POLLOCK, A.M.T.; ARNEODO, F.; DI GIOVANNI, A.; CHANG, Y.L.; CIVITARESE, O.; DE ANGELIS, M.; LETO, C.; VERRECCHIA, F.; RICARD, N.; DI PIPPO, S.; MIDDEI, R.; PENACCHIONI, A V; RUFFINI, R.; SAHAKYAN, N.; ISRAYELYAN, D.; TURRIZIANI, S.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021 vol. 507 p. 5690 - 5702

0035-8711

Blazars research is one of the hot topics of contemporary extragalactic astrophysics. That is because these sources are the mostabundant type of extragalactic 𝛾-ray sources and are suspected to play a central role in multi-messenger astrophysics. We haveused swift_xrtproc, a tool to carry out an accurate spectral and photometric analysis of the Swift-XRT data of all blazars observedby Swift at least 50 times between December 2004 and the end of 2020. We present a database of X-ray spectra, best-fit parametervalues, count-rates and flux estimations in several energy bands of over 31,000 X-ray observations and single snapshots of 65blazars. The results of the X-ray analysis have been combined with other multi-frequency archival data to assemble the broadband Spectral Energy Distributions (SEDs) and the long-term lightcurves of all sources in the sample. Our study shows thatlarge X-ray luminosity variability on different timescales is present in all objects. Spectral changes are also frequently observedwith a "harder-when-brighter" or "softer-when-brighter" behaviour depending on the SED type of the blazars. The peak energyof 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.