Positive or negative? The impact of X-ray feedback on the formation of direct collapse black hole seeds

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Regan , J A , Johansson , P H & Wise , J H 2016 , ' Positive or negative? The impact of X-ray feedback on the formation of direct collapse black hole seeds ' , Monthly Notices of the Royal Astronomical Society , vol. 461 , no. 1 , pp. 111-125 . https://doi.org/10.1093/mnras/stw1307

Title: Positive or negative? The impact of X-ray feedback on the formation of direct collapse black hole seeds
Author: Regan, John A.; Johansson, Peter H.; Wise, John H.
Contributor: University of Helsinki, Department of Physics
Date: 2016-09-01
Language: eng
Number of pages: 15
Belongs to series: Monthly Notices of the Royal Astronomical Society
ISSN: 0035-8711
URI: http://hdl.handle.net/10138/172916
Abstract: A nearby source of Lyman-Werner (LW) photons is thought to be a central component in dissociating H-2 and allowing for the formation of a direct collapse black hole seed. Nearby sources are also expected to produce copious amounts of hydrogen ionizing photons and X-ray photons. We study here the feedback effects of the X-ray photons by including a spectrum due to high-mass X-ray binaries on top of a galaxy with a stellar spectrum. We explicitly trace photon packages emerging from the nearby source and track the radiative and chemical effects of the multifrequency source (E-photon = 0.76 eV -> 7500 eV). We find that X-rays have a strongly negative feedback effect, compared to a stellar only source, when the radiative source is placed at a separation greater than greater than or similar to 1 kpc. The X-rays heat the low and medium density gas in the envelope surrounding the collapsing halo suppressing the mass inflow. The result is a smaller enclosed mass compared to the stellar only case. However, for separations of less than or similar to 1 kpc, the feedback effects of the X-rays becomes somewhat neutral. The enhanced LW intensity at close separations dissociates more H-2 and this gas is heated due to stellar photons alone, the addition of X-rays is then not significant. This distance dependence of X-ray feedback suggests that a Goldilocks zone exists close to a forming galaxy where X-ray photons have a much smaller negative feedback effect and ideal conditions exist for creating massive black hole seeds.
Subject: methods: numerical
stars: Population III
cosmology: theory
DARK-MATTER HALOES
POPULATION III STARS
1ST STARS
EARLY UNIVERSE
VIRIAL TEMPERATURES
PRIMORDIAL GAS
GRAVITATIONAL COLLAPSE
HYDROGEN MOLECULES
SUPERMASSIVE STARS
ACCRETION FLOWS
115 Astronomy, Space science
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