X-ray pre-ionization powered by accretion on the first black holes - I. A model for theWMAPpolarization measurement

X-ray Preionisation Powered by Accretion on the First Black Holes. I: a Model for the WMAP Polarisation Measurement

In this paper we investigate the possibility that there is a first phase of partial ionisation due to X-rays produced by black hole accretion in small-mass galaxies at redshifts 7 < z < 20. This is followed by complete reionisation by stellar sources at z ≃ 7. This scenario is motivated by the large optical depth to Thompson scattering, τe ≃ 0.17 ± 0.04, recently measured by WMAP. But it is als...

X-ray Preionisation Powered by Accretion on the First Black Holes. II: Cosmological Simulations and Observational Signatures

We use numerical simulations of a cosmological volume to study the X-ray ionisation and heating of the intergalactic medium by an early population of accreting black holes. By considering theoretical limits on the accretion rate and observational constraints from the X-ray background and faint X-ray source counts, we find that the maximum value of the optical depth to Thompson scattering that c...

Discovery of the First Accretion-powered Millisecond X-ray Pulsar

Ultraluminous X-ray Sources Powered by Radiatively Efficient Two-phased Super-eddington Accretion onto Stellar Mass Black Holes

The radiation spectra of many of the brightest ultraluminous X-ray sources (ULXs) are dominated by a hard power law component, likely powered by a hot, optically thin corona that Comptonizes soft seed photons emitted from a cool, optically thick black hole accretion disk. Before its dissipation and subsequent conversion into coronal photon power, the randomized gravitational binding energy resp...

Can the anomalous X-ray pulsars be powered by accretion?

The nature of the 5 − 12 s “anomalous” X-ray pulsars (AXPs) remains a mystery. Among the models that have been proposed to explain the properties of AXPs, the most likely ones are: (1) isolated accreting neutron stars evolved from the Thorne-Żytkow objects (TŻOs ) due to complete spiral-in during the common envelope (CE) evolution of high-mass X-ray binaries (HMXBs), and (2) magnetars, which ar...