Giovedì 17 dicembre alle ore 15:00, il dr. Stefano Covino dell’INAF-Osservatorio Astronomico di Brera, Milano, terrà il web-seminar dal titolo: Blazar High-Energy Periodicities: A Cautious Approach.

Abstract

The availability of about a decade of uninterrupted sky monitoring by the Fermi satellite has made it possible to study long-term quasi-periodicities for high-energy sources. It is therefore not a surprise that for several blazars in the recent literature claims for such periodicities, with various levels of confidence, have been reported. The confirmation of these findings could be of tremendous importance for the physical description of this category of sources and have consequences for the gravitational wave background interpretation. In this work, we carry out a temporal analysis of the Fermi light curves for several of the sources mentioned in recent literature by means of standard Fourier analysis. Then, for two of the previous sources with also intense optical monitoring, PG1553+113 and PKS2155-304, an analysis based on Gaussian process regression is also carried out. Main results of the analyses are that highly significance periodicities are not present in the sample, with the partial exception of PG1553+113 that, as already pointed out in the literature, shows a rather convincing periodicity at least in its flaring behavior. Limitations and scope of the reported results are finally discussed.

Web-seminar ad accesso riservato.

Segui la diretta streaming del seminario sul canale YouTube dell’Osservatorio Astronomico d’Abruzzo