Related papers: A Candidate Sub-Parsec Supermassive Binary Black H…
Galaxies are believed to evolve through merging, which should lead to multiple supermassive black holes in some. There are four known triple black hole systems, with the closest pair being 2.4 kiloparsecs apart (the third component is more…
We report our discovery of an extremely rare, low mass, quadruple-lined spectroscopic binary BD-22 5866 (=NLTT 53279, integrated spectral type = M0 V), found during an ongoing search for the youngest M dwarfs in the solar neighborhood. From…
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…
We report that the Sloan Digital Sky Survey quasar SDSS J165043.44+425149.3 is gravitationally lensed into two images, based on observations obtained with the WIYN 3.5 m telescope at the Kitt Peak National Observatory. The lensed quasar, at…
Our discovery of 1SWASP J093010.78+533859.5 as a probable doubly eclipsing quadruple system containing a contact binary with P~0.23 d and a detached binary with P~1.31 d was announced in 2013. Subsequently Koo et al. confirmed the detached…
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…
We report the discovery of two doubly-imaged quasars, SDSS J100128.61+502756.9 and SDSS J120629.65+433217.6, at redshifts of 1.838 and 1.789 and with image separations of 2.86'' and 2.90'', respectively. The objects were selected as lens…
Hierarchical structure formation inevitably leads to the formation of supermassive binary black holes (BBHs) with a sub-parsec separation in galactic nuclei. However, to date there has been no unambiguous detection of such systems. In an…
Double-peaked Balmer lines have been observed in about 150 AGNs and were interpreted preferably as emission from relativistic accretion disks. In this paper, we report the discovery of extreme double-peaked lines in SDSS J0942+0900 and SDSS…
We report the finding of an unobscured type II Active Galactic Nuclei (AGN) candidate, SDSS J012032.19-005501.9 at a relatively high redshift of 0.601,which shows a number of unusual properties. It varies significantly on timescales of…
New spectroscopic observations of the halo hyper-velocity star candidate SDSS J121150.27+143716.2 ($V=17.92$ mag) revealed a cool companion to the hot subdwarf primary. The components have a very similar radial velocity and their absolute…
We have searched quasi-periodic oscillations (QPOs) for BL Lac PKS J2134-0153 in the 15 GHz radio light curve announced by the Owens Valley Radio Observatory 40-m telescope during the period from 2008-01-05 to 2019-05-18, utilizing the…
The radio-loud quasar SDSS J013127.34-032100.1at a redshift z=5.18 is one of the most distant radio-loud objects. The radio to optical flux ratio (i.e. the radio-loudness) of the source is large, making it a promising blazar candidate. Its…
Apparently periodic optical variations of the luminous high-redshift (z=2.06) quasar PSO J334.2028+1.4075 led Liu et al. (2015) to interpret the variability as the orbital period of a binary supermassive black hole (SMBH) residing in a…
A small fraction of quasars have long been known to show bulk velocity offsets in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas…
We report the discovery of an ultra-luminous quasar J030642.51+185315.8 (hereafter J0306+1853) at redshift 5.363, which hosts a super-massive black hole (SMBH) with $M_{BH} = (1.07 \pm 0.27) \times10^{10}~M_\odot$. With an absolute…
Optical quasi-periodic oscillations (QPOs) are the most preferred signs of sub-pc binary black hole (BBH) systems in AGN. In this manuscript, robust optical QPOs are reported in quasar SDSS J1609+1756 at $z=0.347$. In order to detect…
We present a high-cadence multi-epoch analysis of dramatic variability of three broad emission lines (MgII, H$\beta$, and H$\alpha$) in the spectra of the luminous quasar ($\lambda L_{\lambda}$(5100\r{A}) = $4.7 \times 10^{44}$ erg…
Distant luminous quasars provide important information on the growth of the first supermassive black holes, their host galaxies and the epoch of reionization. The identification of quasars is usually performed through detection of their…
We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and…