Related papers: Explaining temporal variations in the jet position…

Detection of periodicity in the broad-band non-thermal emission of blazars has so far been proven to be elusive. However, there are a number of scenarios which could lead to quasi-periodic variations in blazar light curves. For example,…

We present the most extensive and well-sampled long-term multi-band near-infrared (NIR) temporal and spectral variability study of OJ 287, considered to be the best candidate binary supermassive black hole blazar. These observations were…

Supermassive black hole binary systems (SMBHBs) are thought to emit the recently discovered nHz gravitational wave background; however, not a single individual nHz source has been confirmed to date. Long-term radio-monitoring at the Owens…

A diverse range of peculiar properties across the domains of observation have made OJ 287 one of the best-explored BL Lac objects on the issues of relativistic jets and accretion physics as well as the strong theory of gravity. We here…

The 136 year long optical light curve of OJ~287 is explained by a binary black hole model where the secondary is in a 12 year orbit around the primary. Impacts of the secondary on the accretion disk of the primary generate a series of…

Very Long Baseline Interferometry (VLBI) allows for high-resolution and high-sensitivity observations of relativistic jets, that can reveal periodicities of several years in their structure. We perform an analysis of long-term VLBI data of…

In February 2017 the blazar OJ287, one of the best super-massive binary-black-hole-system candidates, was detected for the first time at very high energies (VHEs; E>100GeV) with the ground-based gamma-ray observatory VERITAS. Very high…

The curved shape of the kiloparsec-scale jet of the blazar OJ 287 is analyzed in the framework of the precession of the central engine, on the existence on which a large number of studies over the past decades are based. The data necessary…

The light curve of the quasar OJ 287 extends from 1891 up today without major gaps. Here we summarize the results of the 2005 - 2010 observing campaign. The main results are the following: (1) The 2005 October optical outburst came at the…

Recent intensive observations of the BL Lac object OJ 287 raise a lot of questions on the models of binary black holes, processing jets, rotating helical jets and thermal instability of slim accretion disks. After carefully analyzing their…

The BL Lacertae (BL Lac) object OJ 287 is one of the most dynamic blazars across the directly accessible observational windows: spectral, timing, polarization, and imaging. Apart from behaviors considered characteristics of blazars, it…

The quasar J1918+4937 was recently suggested to harbour a milliparsec-separation binary supermassive black hole (SMBH), based upon modeling the narrow spike in its high-cadence Kepler optical light curve. Known binary SMBHs are extremely…

OJ 287 is a blazar thought to be a binary system containing a ~ 18 billion solar mass primary black hole accompanied by a ~ 150 million solar mass secondary black hole in an eccentric orbit, which triggers electromagnetic flares twice in…

OJ 287 is the best-known supermassive black hole binary candidate in the nanohertz gravitational wave band. It exhibits periodic flares every $\sim$ 12 years, likely caused by collisions of a smaller-mass secondary with the accretion disk…

We report the study of a huge optical intraday flare on November 12, 2021, at 2 am UT, in the blazar OJ287. In the binary black hole model it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our…

We describe a scenario to explain blazar periodicities with timescales of $\sim$ few years. The scenario is based on a binary super-massive black hole (SMBH) system in which one of the two SMBH carries a jet. We discuss the various…

The recent discovery of a roughly simultaneous periodic variability in the light curves of the BL Lac object PG 1553+113 at several electromagnetic bands represents the first case of such odd behavior reported in the literature. Motivated…

Supermassive binary black holes (SBBHs) are a natural outcome of galaxy mergers. Here we show that low-frequency ($f \leq 10^{-6}$ Hz) quasi-periodic variability observed from cosmic blazar sources can provide substantial inductive support…

The nearby radio galaxy M87 offers a unique opportunity to explore the connections between the central supermassive black hole and relativistic jets. Previous studies of the inner region of M87 revealed a wide opening angle for the jet…

We present the first polarimetric space VLBI observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together with contemporaneous ground VLBI observations at 15,…