Related papers: Supercollapsars and their X-ray Bursts
Stars generally form faster than the ambipolar diffusion time, suggesting that several processes short circuit the delay and promote a rapid collapse. These processes are considered here, including turbulence compression in the outer parts…
Super-sonic turbulence fragments molecular clouds (MC) into a very complex density field with density contrasts of several orders of magnitude. A fraction of the gas is locked into dense and gravitationally bound cores, which collapse as…
Several fast radio bursts have been discovered recently, showing a bright, highly dispersed millisecond radio pulse. The pulses do not repeat and are not associated with a known pulsar or gamma-ray burst. The high dispersion suggests…
Long gamma-ray bursts (GRBs) are commonly accepted to originate in the explosion of particularly massive stars, which gives rise to a highly relativistic jet. Internal inhomogeneities in the expanding flow give rise to internal shock waves…
Gamma-ray bursts (GRB) are short and intense bursts of $\sim$100 keV$-$1MeV photons, usually followed by long-lasting decaying afterglow emission in a wide range of electromagnetic wavelengths from radio to X-ray and, sometimes, even to GeV…
Massive stars end their short lives in spectacular explosions, supernovae, that synthesize new elements and drive galaxy evolution. Throughout history supernovae were discovered chiefly through their delayed optical light, preventing…
We revisit the conditions present in supermassive discs (SMDs) formed by the merger of gas-rich, metal-enriched galaxies at red-shift $z\sim 10$. We find that SMDs naturally form hydrostatic cores which go through a rapidly accreting…
The formation of supermassive stars has generally been studied under the assumption of rapid accretion of pristine metal-free gas. Recently it was found, however, that gas enriched to metallicities up to $Z \sim 10^{-3}$ Z$_{\odot}$ can…
Knowledge of the progenitors of core-collapse supernovae is a fundamental component in understanding the explosions. The recent progress in finding such stars is reviewed. The minimum initial mass that can produce a supernova has converged…
We summarize cm through submm observations of the host galaxies of z ~ 6 quasars. These observations reveal the cool molecular gas (the fuel for star formation), the warm dust (heated by star formation), the fine structure line emission…
Ultra-long gamma-ray bursts (ulGRBs) are a new population of GRBs with extreme durations of $\sim 10^{4}$ s. Leading candidates for their origin are blue supergiant collapsars, magnetars, and white dwarf tidal disruption events (WD-TDEs)…
As progenitors of gamma-ray bursts (GRBs), core collapse of massive stars and coalescence of compact object binaries are believed to be powerful sources of gravitational waves (GWs). In the collapsar scenario, a rotating stellar-mass black…
The presence of young massive stars orbiting on eccentric rings within a few tenths of a parsec of the supermassive black hole in the Galactic centre is challenging for theories of star formation. The high tidal shear from the black hole…
We present the results of 3-dimensional simulations of the direct collapse to a black hole of a rotating, 60-solar-mass, zero metallicity, population III star. Because the structure of this star (angular momentum, density and temperature…
There is strong evidence that long duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. In the standard version of the Collapsar model, a broad-lined and luminous Type Ic core-collapse supernova (SN)…
The high redhsift blazars powered by supermassive black holes with masses exceeding $10^9\:M_\odot$ have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the…
We review recent theoretical results on the formation of the first stars and quasars in the universe, and emphasize related open questions. In particular, we list important differences between the star formation process at high redshifts…
Observations show that high-velocity jets stem from deeply embedded young stars, which may still be experiencing infall from their parent cloud cores. Yet theory predicts that, early in this buildup, any outgoing wind is trapped by incoming…
The large number of isolated black holes (IBHs) in the Galaxy, estimated to be 10^8, implies a very high density of 10^-4 pc^-3 and an average distance between IBHs of 10 pc. Our study shows that the magnetic flux, accumulated on the…
The association of long-duration gamma-ray bursts (LGRBs) with Type Ic supernovae presents a challenge to supernova explosion models. In the collapsar model for LGRBs, gamma rays are produced in an ultrarelativistic jet launching from the…