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|Title:||Pulsar timing constraints on the Fermi massive black hole binary blazar population||Authors:||Holgado, A. Miguel
|Issue Date:||2018||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||481||Issue:||1||First Page:||L74||Abstract:||Blazars are a subpopulation of quasars whose jets are nearly aligned with the line of sight, which tend to exhibit multiwavelength variability on a variety of time-scales. Quasi-periodic variability on year-like time-scales has been detected in a number of bright sources, and has been connected to the orbital motion of a putative massive black hole binary. If this were indeed the case, those blazar binaries would contribute to the nanohertz gravitational-wave stochastic background. We test the binary hypothesis for the blazar population observed by the Fermi Gamma-Ray Space Telescope, which consists of BL Lacertae objects and flat-spectrum radio quasars. Using mock populations informed by the luminosity functions for BL Lacertae objects and flat-spectrum radio quasars with redshifts z ≤ 2, we calculate the expected gravitational-wave background and compare it to recent pulsar timing array upper limits. The two are consistent only if a fraction ≲10<SUP>-3</SUP> of blazars hosts a binary with orbital periods <5 yr. We therefore conclude that binarity cannot significantly explain year-like quasi-periodicity in blazars.||URI:||http://hdl.handle.net/20.500.12386/27843||URL:||https://academic.oup.com/mnrasl/article/481/1/L74/5087664||ISSN:||0035-8711||DOI:||10.1093/mnrasl/sly158||Bibcode ADS:||2018MNRAS.481L..74H||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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