Reionization of the Universe by Early-formed Massive Black Holes

Abstract

view Abstract Citations (19) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Reionization of the Universe by Early-formed Massive Black Holes Sasaki, Shin ; Umemura, Masayuki Abstract Based on a recently proposed scenario for the early formation of massive black holes, the possibility that the universe is reionized as a result of the UV radiation from such black holes is investigated. A two- step scenario for the formation of an active compact nucleus is considered: First, an angular momentum-supported disk shrinks into a compact disk because of the Compton drag with the cosmic background radiation (CBR). Second, the disk is adiabatically heated, and then turbulent viscosity works to convert the gravitational energy into powerful radiation. Within this context, it is found that the overall reionization of the universe by high-redshift black hole systems is possible. The reionization epoch depends upon the power-law index of the density fluctuations at the recombination epoch. If the spectral index is in the range of n ~> - 1.7, the universe is reionized overall by z ~ 150, having a Gunn-Peterson optical depth below the 2 σ upper limits inferred from recent observations of QSOs at 2.6 < z < 4.2. The UV flux from early-formed massive black holes may provide additional sources of UV background intensity to satisfy the "proximity effect" of Lyα absorption lines in QSO spectra. In addition, the Compton γ- parameter of the CBR is considerably below the observed upper limits from COBE results. If n <~ - 1.5, the results are not in conflict with the observed soft X-ray background. The predicted helium Gunn-Peterson effect and mass function of relic black holes are also presented. Publication: The Astrophysical Journal Pub Date: May 1996 DOI: 10.1086/177131 Bibcode: 1996ApJ...462..104S Keywords: BLACK HOLE PHYSICS; COSMOLOGY: EARLY UNIVERSE; GALAXIES: INTERGALACTIC MEDIUM; GALAXIES: QUASARS: GENERAL full text sources ADS |