Positive or Negative? The Impact of X-ray Feedback on the Formation of   Direct Collapse Black Hole Seeds
  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 ionising 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 multi-frequency source $(E_{\rm photon} = \rm{0.76\ eV \rightarrow 7500\ eV}$). 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 $\gtrsim 1 \ \rm kpc$. 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 $\lesssim 1 \ \rm kpc$, 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. 
John A. Regan (ICC, Durham), Peter H. Johansson (Helsinki) and John H.   Wise (Georgia Tech)
astro-ph.GA