Related papers: SDSS J092712.65+294344.0: Recoiling Black Hole or …

In several previous studies, quasars exhibiting broad emission lines with >1000 km/s velocity offsets with respect to the host galaxy rest frame have been discovered. One leading hypothesis for the origin of these velocity-offset broad…

SDSSJ092712.65+294344.0 was identified by the SDSS as a quasar, but has the unusual property of having two emission line systems offset by 2650 km/s. One of these contains the usual combination of broad and narrow lines, the other only…

All stellar mass black holes have hitherto been identified by X-rays emitted by gas that is accreting onto the black hole from a companion star. These systems are all binaries with black holes below 30 M$_{\odot}$$^{1-4}$. Theory predicts,…

Binaries containing a compact object orbiting a supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely challenging. Here, we report quasi-periodic variability in X-ray…

One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole system in their cores. Here we present an observational evidence for the first…

Because most large galaxies contain a central black hole, and galaxies often merge, black-hole binaries are expected to be common in galactic nuclei. Although they cannot be imaged, periodicities in the light curves of quasars have been…

We found that SDSS J094002.56+274942.0 underwent a superoutburst in 2019 February based on our observations and Zwicky Transient Facility (ZTF) data. This object showed shallow eclipses during this superoutburst and we established the…

New long-term Very Long Baseline Array observations of the well-known jet in the M87 radio galaxy at 43 GHz show that the jet experiences a sideways shift with an approximately 8-10 yr quasi-periodicity. Such jet wobbling can be indicative…

We have carried out a systematic search for recoiling supermassive black holes (rSMBH) using the Chandra Source and SDSS Cross Matched Catalog. From the survey, we have detected a potential rSMBH, 'CXO J101527.2+625911' at z=0.3504. The CXO…

The Sloan Digital Sky Survey (SDSS) source J102347.6+003841 was recently revealed to be a binary 1.69 millisecond radio pulsar with a 4.75 hr orbital period and a ~0.2 M_sun companion. Here we analyze the SDSS spectrum of the source in…

We present infrared JHK photometry of the cataclysmic variable SDSS J123813.73-033933.0 (SDSS1238)and analyze it along with optical spectroscopy, demonstrating that the binary system is most probably comprised of a massive white dwarf with…

In a previous work, we have identified the spin of the dominant black hole of a binary from its jet properties. Analysing Very Long Baseline Array (VLBA) observations of the quasar S5~1928+738, taken at $15$-GHz during $43$ epochs between…

Optical periodicity QSOs found by transient surveys are suggested to be sub-parsec supermassive binary black holes (BBHs). An intriguing interpretation for the periodicity of some of those QSOs is that the continuum is radiated from the…

Supermassive black hole (SMBH) binaries are expected in a Lambda CDM cosmology given that most (if not all) massive galaxies contain a massive black hole at their center. So far, however, direct evidence for such binaries has been elusive.…

With upcoming facilities capable of detecting photometric and gravitational wave signals from supermassive black hole (SMBH) binaries, studying their long-term accretion-driven variability is timely. OJ287 is a bright, nearby ($z=0.3$), and…

We report the detection of orbital decay in the 12.75-min, detached binary white dwarf (WD) SDSS J065133.338+284423.37 (hereafter J0651). Our photometric observations over a 13-month baseline constrain the orbital period to 765.206543(55) s…

In the local universe, black holes of $10^{5-6}$ M$_{\odot}$ are hosted in galaxies displaying a variety of stellar profiles and morphologies. These black holes are the anticipated targets of LISA, the Laser Interferometer Space Antenna…

Mass distribution of black holes identified through X-ray emission suggests a paucity of black holes in the mass range of 3 to 5 solar masses. Modified theories have been devised to explain this mass gap, and it is suggested that natal…

Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. Great effort has been made during the past several decades to search for BBHs among quasars; however,…

Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following…