Related papers: A new apparent quasar pair: Q2225-403A,B

We present new Keck observations of giant arcs in the cluster Abell 2390. High resolution two-dimensional spectra of two arcs show metal lines at z=4.040 +/- 0.005 with Lyman-alpha emission spatially separated from the stellar continuum. In…

Low-mass and brown dwarfs have recently been found as wide companions to many nearby stars, formerly believed to be single. Wide binaries are usually found as common proper motion pairs. Sometimes, more than two objects share the same large…

We report the discovery of a quasar close to SDSS J0927+2943 (z = 0.713), which is a massive binary / recoiling black hole candidate. The companion quasar is at a projected distance of 125 h_70^{-1} kpc and exhibits a radial velocity…

We present the discovery of a triplet of quasars at z~1.51. The whole system is well accommodated within 25 arcsec (i.e., 200 kpc in projected distance). The velocity differences among the three objects (as measured through the broad MgII…

We report the discovery of 11 newly found quasars behind the stellar disks of the spiral galaxies M31 and M33 in the fields covered by the Local Group Galaxy Survey. Their redshifts range from 0.37 to 2.15. Most are X-ray, UV, and IR…

Binary quasars are extremely rare objects, used to investigate clustering on very small scales at different redshifts. The cases where the two quasar components are gravitationally bound, known as physical binary quasars, can also exhibit…

We report the discovery of the first known probable case of a physical triple quasar (not a gravitational lens). A previously known double system, QQ 1429-008 at z = 2.076, is shown to contain a third, fainter QSO component at the same…

We present Plateau de Bure Interferometer observations of far infra-red emission lines in BRI 0952-0115, a lensed quasar at z=4.4 powered by a super-massive black hole (M_BH=2x10^9 M_sun). In this source, the resolved map of the [CII]…

The rare close projection of two quasars on the sky provides the opportunity to study the host galaxy environment of a foreground quasar in absorption against the continuum emission of a background quasar. For over a decade the "Quasars…

We report the discovery of a unique quasar-dusty star-forming galaxy (DSFG) system at $z = 5.63$, consisting of the bright quasar J1133+1603 ($M_{\rm UV} = -27.42$) and its compact, dust-obscured companion, J1133c. ALMA observations reveal…

We characterize the physical properties of the cool T ~10^4 K circumgalactic medium surrounding z ~2-3 quasar host galaxies, which are predicted to evolve into present day massive ellipticals. Using a statistical sample of 14 quasar pairs…

We present ALMA [CII] 158 $\mu$m line and underlying far-infrared (FIR) continuum emission observations ($0''.57 \times 0''.46$ resolution) toward a quasar-quasar pair system recently discovered at $z = 6.05$ (Matsuoka et al. 2024). The…

Dual quasars separated at kiloparsec scale are widely regarded as precursors to binary supermassive black holes and offer a key insight into the dynamical evolution of galaxy mergers. Our series of studies focus on searching for dual…

We report the discovery of a new gravitationally lensed quasar from the Sloan Digital Sky Survey, SDSS J090334.92+502819.2. This object was targeted for SDSS spectroscopy as a Luminous Red Galaxy (LRG), but manual examination of the…

We present the first results from a new survey for high-redshift $(z\gtrsim5)$ gravitationally lensed quasars and close quasar pairs. We carry out candidate selection based on the colors and shapes of objects in public imaging surveys, then…

We report the discovery of the faint (V=21.7) quasar QSO03027-0010 at z=2.808 in the vicinity of Q0302-003, one of the few quasars observed with STIS to study intergalactic HeII absorption. Together with another newly discovered QSO at…

We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the LAMOST during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m telescope, XSTPS…

We present new near-infrared (rest-frame UV-to-optical) spectra of the high redshift, gravitationally lensed quasar B 1422+231 (z=3.62). Diagnostic emission lines of FeII, [OIII]5007, and Hb, commonly used to determine the excitation,…

We report the discovery of a cluster of galaxies in the field of UM425, a pair of quasars separated by 6.5arcsec. Based on this finding, we revisit the long-standing question of whether this quasar pair is a binary quasar or a…

We present optical spectroscopy of the close companions of 22 low redshift (z<0.5) quasars (QSO) selected from a larger sample of QSO in the SDSS Stripe82 region for which both the host galaxy and the large scale environments have been…