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The two young star disks in the central parsec of the galaxy: properties, dynamics and formation
We report the definite spectroscopic identification of 40 OB supergiants, giants and main sequence stars in the central parsec of the Galaxy. Detection of their absorption lines have become possible
An ultraluminous X-ray source powered by an accreting neutron star
The majority of ultraluminous X-ray sources are point sources that are spatially offset from the nuclei of nearby galaxies and whose X-ray luminosities exceed the theoretical maximum for spherical
Stellar Disk in the Galactic Center: A Remnant of a Dense Accretion Disk?
Observations of the Galactic center revealed a population of young massive stars within 0.4 pc from Sgr A*—the presumed location of a supermassive black hole. The origin of these stars is a puzzle as
Neutrino-cooled Accretion Disks around Spinning Black Holes
We calculate the structure of accretion disks around Kerr black holes for accretion rates = 0.001-10 M☉ s-1. Such high- disks are plausible candidates for the central engine of gamma-ray bursts. Our
Plasma Ejection from Magnetic Flares and the X-Ray Spectrum of Cygnus X-1
The hard X-rays in Cyg X-1 and similar black hole sources are possibly produced in an active corona atop an accretion disk. We suggest that the observed weakness of X-ray reflection from the disk is
Untwisting magnetospheres of neutron stars
Magnetospheres of neutron stars are anchored in the rigid crust and can be twisted by sudden crustal motions (starquakes). The twisted magnetosphere does not remain static and gradually untwists,
Gravitational Bending of Light Near Compact Objects
A photon emitted near a compact object at an angle α with respect to the radial direction escapes to infinity at a different angle ψ > α. This bending of light is caused by a strong gravitational
A flaring magnetar in FRB 121102
The persistent radio counterpart of FRB 121102 is estimated to have $N\sim 10^{52}$ particles, energy $E_N\sim 10^{48}$ erg, and size $R\sim 10^{17}$ cm. The source can be a nebula inflated and
Neutrino heating near hyper-accreting black holes
Hyper-accretion discs around black holes emit copious neutrinos and anti-neutrinos. A fraction of the emitted neutrinos convert to electron–positron plasma above the disc through the annihilation
Collisional mechanism for gamma‐ray burst emission
Nuclear and Coulomb collisions in gamma-ray burst (GRB) jets create a hot e ± plasma. This collisional heating starts when the jet is still opaque, and extends to the transparent region. The e ±