http://arxiv.org/abs/2301.08242
The Lyman-Werner (LW) radiation field is a key ingredient in the chemo-thermal evolution of gas in the Early Universe, as it dissociates H2 molecules, the primary cooling channel in an environment devoid of metals and dust. Despite its important role, it is still not implemented in cosmological simulations on a regular basis, in contrast to the general UV background. This is in part due to uncertainty in the source modelling, their spectra and abundance, as well as the detailed physics involved in the propagation of the photons and their interactions with the molecules. To overcome these difficulties, we present here a model (with the relative fit) for the mean LW intensity during the first billion years after the Big Bang, obtained by post-processing the high-resolution FiBY simulations with an approximated radiative transfer method that employs accurate cross sections for H2, as well as for H- and H2+, the chemical species associated with its formation. Absorption by neutral Hydrogen in the IGM and various spectral models for Population III and Population II stars are also included. Our model can be easily applied to other simulations or semi-analytical models as an external homogeneous source of radiation that regulates the star formation in low-mass halos at high-z. We also show how to account for spatial inhomogeneities in the LW radiation field, originating from massive star-forming galaxies that dominate the photon budget up to distances of $\sim100$ proper kpc. Such inhomogeneities have a strong impact on the H2 abundance and the feasibility of scenarios such as the formation of Direct Collapse Black Holes (DCBHs).
A. Incatasciato, S. Khochfar and J. Oñorbe
Fri, 20 Jan 23
30/72
Comments: 20 pages, 16 figures, plus 4 figures in the appendices. Main result in Figure 16
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