Astrophysical implications of binary black holes in BL Lacertae objects

Abstract

Some BL Lacertae objects show a periodic behaviour in their light curves that is often attributed to the orbital motion of a central binary black hole system. On this basis, and assuming a circular orbit, Rieger and Mannheim have recently proposed a method to determine the orbital parameters of the binary system from the observed quantities, {\it i.e.} the signal periodicity, the flux ratio between maximum and minimum signal and the power law spectral index of the photon flux. However, since these binary black holes are expected to originate from galactic mergers, they could well be on eccentric orbits, which might not circularize for a substantial time. We therefore generalize the treatment proposed by Rieger and Mannheim by taking into account the effect of the orbital eccentricity of the binary system. We apply the model to three well-observed Markarian objects: MKN 501, MKN 421 and MKN 766 that most likely host a binary system in their centers. Some astrophysical implications of this model are also investigated with particular emphasis to the gravitational radiation emission from the binary black holes. Under particular conditions (e.g. for some values of the orbital separation, eccentricity and Lorentz factor) one can obtain signals above the sensitivity threshold of the LISA detector.

8 pages, 4 figures, uses aa.cls. Astronomy And Astrophysics, in press

References in corpus (3)

• The gravitational wave signal from the Galactic disk population of binaries containing two compact objects
• Fe K_alpha line: A tool to probe massive binary black holes in Active Galactic Nuclei?
• Astrophysical implications of gravitational microlensing of gravitational waves

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• A Very Close Binary Black Hole in a Giant Elliptical Galaxy 3C 66B and its Black Hole Merger
• Supermassive Black Hole Binaries: The Search Continues
• The binary black hole scenario for the BL Lacertae object AO 0235+16
• On the central black hole mass in Mkn~501
• A note on gravitational wave lensing
• A super massive black hole binary in 3C66B: future observational perspectives
• Binary black holes in Mkns as sources of gravitational radiation for space based interferometers
• Multiwavelength periodicity study of Markarian 501
• Helical motion and the origin of QPO in blazar-type sources