New Paper: Effects of X-rays on Initial Black Hole Growth

Today, we have submitted a paper (arXiv) on the initial growth of massive black hole seeds to The Astrophysical Journal.

The growth of supermassive black holes (BHs) has been intricately linked to galaxy formation and evolution and is a key ingredient in the assembly of galaxies. In this study, we investigate the growth of massive BHs at high redshift. In particular, we simulate direct collapse formation scenario, where a massive BH seed forms from the collapse of a primordial gas cloud that is kept from cooling by a strong UV radiation field. In these simulations, for the first time, we take into account the effects of X-ray feedback during the initial growth of the massive seed. We include many other relevant physical processes, such as star formation and feedback and the shielding of radiation that can dissociate molecular hydrogen and/or ionize hydrogen and helium. We follow the growth of the central massive BHs for 100 million years, and we find that the maximum accretion rate is determined by the local gas thermodynamics, whereas the duty cycle is determined by the gas reservoir from which the BH feeds. We conclude that radiative feedback from the central BH plays an important role in star formation in the nuclear regions and stifling initial BH growth, relative to the typical Eddington rate argument, and that initial BH growth might be affected by the local radiation field. This further complicates the explanation for the existence of supermassive BHs in the early universe.

New Postdoc: KwangHo Park

KwangHo Park has arrived in the CRA this week as a new TCAN postdoc, and his primary mentor will be Prof. Tamara Bogdanovic. He works on radiation hydrodynamics as applied to intermediate mass holes, feedback by accretion onto black holes, and black hole growth in the early Universe.  He previously held a Urania E. Scott Postdoctoral Fellow at Carnegie Mellon University, and he received his Ph.D. from the University of Maryland under the supervision of Massimo Ricotti.

02 Sept 2014

  • (abs, pdf) Sparre et al., The star formation main sequence and stellar mass assembly of galaxies in the Illustris simulation
  • (abs, pdf) Capelo et al., Growth and activity of black holes in galaxy mergers with varying mass ratios
  • (abs, pdf) Atek et al., New Constraints on the Faint-end of the UV Luminosity Function at z~7-8 using the Gravitational Lensing of the Hubble Frontier Fields Cluster A2744