Contributed Talk - Splinter TimeDomain

Wednesday, 15 September 2021, 14:52   (virtual TimeD)

Building a robust sample of periodic gamma-ray blazars detected with the Fermi-LAT

S. Buson, P. Penil, A. Dominguez, M. Ajello, S. Larsson on behalf of the Fermi-LAT collaboration
Universit├Ąt W├╝rzburg

Blazars display variability on a wide range of timescales, from minutes to years. They constitute the overwhelming majority of sources detected at gamma-ray energies by the Fermi-LAT, with more than 3000 firmly reported in the LAT source catalogs. Using the more than a decade of continuous monitoring provided by the Fermi-LAT in the MeV-GeV range, we have performed the first systematic study to pinpoint potential periodic behaviour at gamma rays in a large set of gamma-ray blazars. This contribution will show the results of this study, obtained by applying to the Fermi-LAT blazars several well-established methods for searching for periodic behaviour in astrophysical sources. We will discuss results for the most promising periodic candidates selected from our previous work, extending the Fermi-LAT light curves for a total of twelve years. These improvements have allowed us to build the first sample of blazars that display a periodicity detected at a significance >5sigma. Finally, we will discuss the potential origins of periodic behaviour observed in blazars.