We present optical spectroscopy of the nearest quasar pair listed in the 13th edition of the Véron-Cetty & Véron catalogue, i.e. the two quasars SDSS J15244...

We present integral field spectroscopic observations of the quadruple-lensed QSO SDSS 1004+4112 taken with the fiber system INTEGRAL at the William Herschel...

In this Letter we report the detection of a strong and extremely blueshifted X-ray absorption feature in the 1 Ms Chandra spectrum of CXOCDFS J033260.0-274748...

The paradox of apparent optical associations of galaxies with very different redshifts, the so-called anomalous redshift problem, is around 35 years old, but is...

We present submillimeter observations of the z= 3.653 quasar SDSS 160705+533558 together with data in the optical and infrared. The object is unusually bright...

We study three high magnification microlensing events, generally recognized as probable caustic crossings, in the optical light curves of the multiply imaged...

Aims. We aim to unveil the structure of the continuum and broad-emission line (BEL) emitting regions in the gravitationally lensed quasar SDSS J1339+1310 by...

Aims: We aim to use signatures of microlensing induced by stars in the foreground lens galaxy to infer the size of the accretion disk in the gravitationally...