相关论文: Two Close-Separation Quasar-Quasar Pairs in the La…

We present spectroscopic observations with Keck/LRIS of LBQS 0015+0239, a pair of quasars at z = 2.45 with a separation of $\Delta\theta = 2.2$ arcsec (projected linear distance of 17.8 $h_{70}^{-1}$ kpc, for $\Omega_m = 0.3$, $\Lambda =…

We report the discovery of a close quasar pair candidate at $z=5.66$, J2037--4537. J2037--4537 is resolved into two quasar images at the same redshift in ground-based observations. Followup spectroscopy shows significant differences in both…

We report the discovery of a pair of z = 4.25 quasars with a separation of 33 arcseconds. The brighter of the two objects was identified as a high-redshift quasar candidate from Sloan Digital Sky Survey multicolor imaging data, and the…

Optically bright, wide separation double (gravitationally lensed) quasars can be easily monitored, leading to light curves of great importance in determining the Hubble constant and other cosmological parameters, as well as the structure of…

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…

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 serendipitous discoveries of companion galaxies to two high-redshift quasars. SDSS J025617.7+001904 is a z=4.79 quasar included in our recent survey of faint quasars in the SDSS Stripe 82 region. The initial MMT slit…

We report the discovery of a quasar pair at z=5 separated by 21 arcsec. Both objects were identified as quasar candidates using simple color selection techniques applied to photometric catalogs from the CFHT Legacy Survey (CFHTLS). Spectra…

We report the discovery of a new gravitational lens candidate Q2138-431AB, comprising two quasar images at a redshift of 1.641 separated by 4.5 arcsecs. The spectra of the two images are very similar, and the redshifts agree to better than…

We report the discovery of two quasars at a redshift of $z$ = 6.05, in the process of merging. They were serendipitously discovered from the deep multi-band imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program…

Quasar pairs are either physically distinct binary quasars or the result of gravitational lensing. The majority of known pairs are in fact lenses, with a few confirmed as binaries, leaving a population of objects that have not yet been…

Close quasar pairs are rare products of galaxy mergers in which both supermassive black holes (SMBHs) are actively accreting, offering strong constraints on merger-driven active galactic nuclei (AGN) evolution. Identifying close quasar…

The V=16.9 quasar FBQ 0951+2635 at redshift z=1.24 appears double on CCD exposures taken in subarcsecond seeing. The two objects are separated by 1.1" and differ in brightness by 0.9 mag. VLA observations show the radio source to be double…

LBQS 0103$-$2753 is a binary quasar with a separation of only 0.3 arcsec. The projected spacing of 2.3 kpc at the distance of the source (z = 0.848) is much smaller than that of any other known binary QSO. The binary nature is demonstrated…

We present results of a systematic search for gravitationally lensed quasars in Pan-STARRS1. Our final sample of candidates comprises of 91 systems, not including 25 rediscovered lensed quasars and quasar pairs. In the absence of…

We present HST and UKIRT spectra and images of the 2 kpc binary quasar LBQS 0103-2753 (z=0.858). The HST images (V- and I-band) show tidal features demonstrating that this system is a major galaxy merger in progress. A two-color composite…

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 two-image gravitationally lensed quasar, SDSS J024634.11-082536.2 (SDSS J0246-0825). This object was selected as a lensed quasar candidate from the Sloan Digital Sky Survey (SDSS) by the same algorithm that…

This paper reviews the question of whether the wide separation double quasar Q2138-431 is a gravitational lens. From early work, the two quasar images are known to have almost identical spectra and redshifts, but no lensing galaxy has so…

Quasars are effective tracers of the large-scale distribution of galaxies at high redshift thanks to their high luminosity and dedicated surveys. Previous studies have shown that quasars exhibit a bias similar to that of rich groups,…