A black hole x-ray binary (XRB) system forms when gas is stripped from a normal star and
accretes onto a black hole, which heats the gas sufficiently to emit x-rays. We report a …

Recent X-ray polarimetric data on the prototypical black hole X-ray binary Cyg X-1 from the
Imaging X-ray Polarimetry Explorer present tight constraints on accretion geometry in the …

We extend our recent work on black hole spin in X-ray binary systems to include an analysis
of 189 archival NuSTAR observations from 24 sources. Using self-consistent data reduction …

Einstein's theory of general relativity is one of the pillars of modern physics and it is our
standard framework for describing gravitational fields and the spacetime structure. So far …

We present the Black Hole Explorer (BHEX), a mission that will produce the sharpest images
in the history of astronomy by extending submillimeter Very-Long-Baseline Interferometry …

Wormholes are hypothetical topologically-non-trivial structures of spacetime. From the
theoretical point of view, the possibility of their existence is challenging but cannot be ruled …

We report the first detection of the X-ray polarization of the bright transient Swift J1727. 8−
1613 with the Imaging X-ray Polarimetry Explorer. The observation was performed at the …

Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients can appear when
the source is in the low-hard and hard-intermediate states. The spectral-timing evolution of …

Context. We present a systematic X-ray spectral-timing study of the recently discovered,
exceptionally bright black hole X-ray binary system MAXI J1820+ 070. Our analysis focuses …

The equatorial symmetry of the Kerr black hole is generically broken in models of quantum
gravity. Nevertheless, most phenomenological models start from the assumption of …