The thermal evolution of the cosmic gas decoupled from that of the cosmic microwave background (CMB) at a redshift zsimilar to200. Afterwards and before the first stars had formed, the cosmic neutral hydrogen absorbed the ...

The binary system J0737-3039AB includes two pulsars in a highly relativistic orbit. The pulsed radio flux from pulsar B brightens considerably during two portions of each orbit. This phenomenon cannot be naturally triggered ...

The Lyalpha absorption spectrum of the highest redshift quasars indicates that they are surrounded by giant H II regions, a few megaparsecs in size. The neutral gas around these H II regions should emit 21 cm radiation in ...

Strong intergalactic shocks are a natural consequence of structure formation in the universe. These shocks are expected to deposit large fractions of their thermal energy in relativistic electrons (xi(e)similar or equal ...

The discovery of hundreds of young, bright stars within a parsec from the massive black hole Sagittarius A* at the center of the Galaxy presents a challenge to star formation theories. The requisite Roche densities for the ...

The origin and structure of magnetic fields in gamma-ray burst (GRB) fireball plasmas are two of the most important open questions in all GRB models. It has been claimed that recent measurements of gamma-ray polarization ...

The most luminous galaxies in the present universe are found at the centers of the most massive dark matter halos: rich galaxy clusters. In the LambdaCDM cosmology, such massive halo cores are present at redshift z = 6 ...

The comoving mass density of massive black hole (MBH) remnants from pregalactic star formation could have been similar in magnitude to the mass density of supermassive black holes (SMBHs) in the present-day universe. We ...

The supermassive black hole at the Galactic center harbors a bound cluster of massive stars that should leave neutron star remnants. Extrapolating from the available data, we estimate that similar to1000 radio pulsars may ...