The Formation and Evolution of the First Massive Black Holes

The first massive astrophysical black holes likely formed at high redshifts (z>10) at the centers of low mass (~10^6 Msun) dark matter concentrations. These black holes grow by mergers and gas accretion, evolve into the population of bright quasars observed at lower redshifts, and eventually leave the supermassive black hole remnants that are ubiquitous at the centers of galaxies in the nearby universe. The astrophysical processes responsible for the formation of the earliest seed black holes are poorly understood. The purpose of this review is threefold: (1) to describe theoretical expectations for the formation and growth of the earliest black holes within the general paradigm of hierarchical cold dark matter cosmologies, (2) to summarize several relevant recent observations that have implications for the formation of the earliest black holes, and (3) to look into the future and assess the power of forthcoming observations to probe the physics of the first active galactic nuclei.Comment: 39 pages, review for "Supermassive Black Holes in the Distant Universe", Ed. A. J. Barger, Kluwer Academic Publisher

The Formation of the First Massive Black Holes

Supermassive black holes (SMBHs) are common in local galactic nuclei, and SMBHs as massive as several billion solar masses already exist at redshift z=6. These earliest SMBHs may grow by the combination of radiation-pressure-limited accretion and mergers of stellar-mass seed BHs, left behind by the first generation of metal-free stars, or may be formed by more rapid direct collapse of gas in rare special environments where dense gas can accumulate without first fragmenting into stars. This chapter offers a review of these two competing scenarios, as well as some more exotic alternative ideas. It also briefly discusses how the different models may be distinguished in the future by observations with JWST, (e)LISA and other instruments.Comment: 47 pages with 306 references; this review is a chapter in "The First Galaxies - Theoretical Predictions and Observational Clues", Springer Astrophysics and Space Science Library, Eds. T. Wiklind, V. Bromm & B. Mobasher, in pres

A Rare Sequela of Constriction Band Syndrome: Case Report.

The patient in this case report is a 19-year-old man who presented with left foot cauliflower lesion. He complained of an inability to wear proper shoes, in addition to an unpleasant appearance of his foot. The lesion was present since his birth. Based on history and physical examination, the top 2 differential diagnoses at this stage were pediatric neurofibroma and constriction band syndrome (CBS). Laboratory investigations and x-ray were ordered for the patient. X-ray showed absence of most of the phalanges of the first, second, and third toes, with swelling of the overlying soft tissues of the foot. CBS was confirmed. Excision of the lesion was done along with skin graft applied on the area. Biopsy showed skin with dermal fibrosis and extensive adipose tissue infiltration without any sign of atypia or malignancy. The patient was discharged with regular follow-up appointments

Nonlinear Instabilities in Shock-Bounded Slabs

(substantial changes to section 3.2, otherwise minor) We present an analysis of the hydrodynamic stability of a cold slab bounded by two accretion shocks. Previous numerical work has shown that when the Mach number of the shock is large the slab is unstable. Here we show that to linear order both the bending and breathing modes of such a slab are stable. However, nonlinear effects will tend to soften the restoring forces for bending modes, and when the slab displacement is comparable to its thickness this gives rise to a nonlinear instability. The growth rate of the instability, above this threshold but for small bending angles, is $\sim c_sk (k\eta)^{1/2}$, where $\eta$ is the slab displacement. When the bending angle is large the slab will contain a local vorticity comparable to $c_s/L$, where $L$ is the slab thickness. We discuss the implications of this work for gravitational instabilities of slabs. Finally, we examine the cases of a decelerating slab bounded by a single shock and a stationary slab bounded on one side by thermal pressure. The latter case is stable, but appears to be a special case. The former case is subject to a nonlinear overstability driven by deceleration effects. We conclude that shock bounded slabs with a high density compression ratio generically produce substructure with a strong local shear, a bulk velocity dispersion like the sound speed in the cold layer and a characteristic scale comparable to the slab thickness.Comment: aastex, 42 pages, 930602