SIMBAD references

2018A&A...615A.118S - Astronomy and Astrophysics, volume 615A, 118-118 (2018/7-1)

Quasi-periodicities of BL Lacertae objects.

SANDRINELLI A., COVINO S., TREVES A., HOLGADO A.M., SESANA A., LINDFORS E. and RAMAZANI V.F.

Abstract (from CDS):

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 Fermiγ-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.

Abstract Copyright: © ESO 2018

Journal keyword(s): gamma rays: galaxies - gamma rays: general - BL Lacertae objects: general - galaxies: active - galaxies: jets

Simbad objects: 7

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2019.09.21-12:03:15

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