We review the reports of possible year-long quasi-periodicities of BL Lac objects in the γ-ray and optical bands, and present a homogeneous time analysis of the light curves of PKS2155−304, PG1553+113, and BL Lac. Based on results from a survey covering the entire Fermi γ-ray sky we have estimated the fraction of possible quasi-periodic BL Lac objects. We compared the cyclical behaviour in BL Lac objects with that derived from the search of possible optical periodicities in quasars, and find that at z . 1 the cosmic density of quasi-periodic BL Lac objects is larger than that of quasi-periodic quasars. If the BL Lac quasi-periodicities were due to a supermassive binary black hole (SBBH) scenario, there could be a tension with the upper limits on the gravitational wave background measured by the pulsar timing array. The argument clearly indicates the difficulties of generally associating quasi-periodicities of BL Lac objects with SBBHs.

Sandrinelli, A., Covino, S., Treves, A., Holgado, A., Sesana, A., Lindfors, E., et al. (2018). Quasi-periodicities of BL Lacertae objects. ASTRONOMY & ASTROPHYSICS, 615 [10.1051/0004-6361/201732550].

Quasi-periodicities of BL Lacertae objects

Sesana A.;
2018

Abstract

We review the reports of possible year-long quasi-periodicities of BL Lac objects in the γ-ray and optical bands, and present a homogeneous time analysis of the light curves of PKS2155−304, PG1553+113, and BL Lac. Based on results from a survey covering the entire Fermi γ-ray sky we have estimated the fraction of possible quasi-periodic BL Lac objects. We compared the cyclical behaviour in BL Lac objects with that derived from the search of possible optical periodicities in quasars, and find that at z . 1 the cosmic density of quasi-periodic BL Lac objects is larger than that of quasi-periodic quasars. If the BL Lac quasi-periodicities were due to a supermassive binary black hole (SBBH) scenario, there could be a tension with the upper limits on the gravitational wave background measured by the pulsar timing array. The argument clearly indicates the difficulties of generally associating quasi-periodicities of BL Lac objects with SBBHs.
Articolo in rivista - Articolo scientifico
BL Lacertae objects: general; Galaxies: active; Galaxies: jets; Gamma rays: galaxies; Gamma rays: general
English
2018
615
A118
none
Sandrinelli, A., Covino, S., Treves, A., Holgado, A., Sesana, A., Lindfors, E., et al. (2018). Quasi-periodicities of BL Lacertae objects. ASTRONOMY & ASTROPHYSICS, 615 [10.1051/0004-6361/201732550].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/290629
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