%0 Generic %1 ge2017effect %A Ge, Qi %A Wise, John %D 2017 %K Lya collapse trapping %T On the effect of Lyman alpha trapping during the initial collapse of massive black hole seeds %U http://arxiv.org/abs/1706.01467 %X One viable seeding mechanism for supermassive black holes is the direct gaseous collapse route in pre-galactic dark matter halos, producing objects on the order of $10^4 - 10^6$ solar masses. These events occur when the gas is prevented from cooling below $10^4$ K that requires a metal-free and relatively H$_2$-free medium. The initial collapse cools through atomic hydrogen transitions, but the gas becomes optically thick to the cooling radiation at high densities. We explore the effects ofLyman-$\alpha$ trapping in such a collapsing system with a suite of Monte Carlo radiation transport calculations in uniform density and isotropic cases that are based from a cosmological simulation. Our method includes both non-coherent scattering and two-photon line cooling. We find that Lyman-$\alpha$ radiation is marginally trapped in the parsec-scale gravitationally unstable central cloud, allowing the temperature to increase to 50,000 K at a number density of $3 10^4$ cm$^-3$ and increasing the Jeans mass by a factor of five. The effective equation of state changes from isothermal at low densities to have an adiabatic index of 4/3 around the temperature maximum and then slowly retreats back to isothermal at higher densities. Our results suggest that Lyman-$\alpha$ trapping delays the initial collapse by raising the Jeans mass. Afterward the high density core cools back to $10^4$ K that is surrounded by a warm envelope whose inward pressure may alter the fragmentation scales at high densities.

@misc{ge2017effect, abstract = {One viable seeding mechanism for supermassive black holes is the direct gaseous collapse route in pre-galactic dark matter halos, producing objects on the order of $10^4 - 10^6$ solar masses. These events occur when the gas is prevented from cooling below $10^4$ K that requires a metal-free and relatively H$_2$-free medium. The initial collapse cools through atomic hydrogen transitions, but the gas becomes optically thick to the cooling radiation at high densities. We explore the effects ofLyman-$\alpha$ trapping in such a collapsing system with a suite of Monte Carlo radiation transport calculations in uniform density and isotropic cases that are based from a cosmological simulation. Our method includes both non-coherent scattering and two-photon line cooling. We find that Lyman-$\alpha$ radiation is marginally trapped in the parsec-scale gravitationally unstable central cloud, allowing the temperature to increase to 50,000 K at a number density of $3 \times 10^4$ cm$^{-3}$ and increasing the Jeans mass by a factor of five. The effective equation of state changes from isothermal at low densities to have an adiabatic index of 4/3 around the temperature maximum and then slowly retreats back to isothermal at higher densities. Our results suggest that Lyman-$\alpha$ trapping delays the initial collapse by raising the Jeans mass. Afterward the high density core cools back to $10^4$ K that is surrounded by a warm envelope whose inward pressure may alter the fragmentation scales at high densities.}, added-at = {2017-06-07T09:51:14.000+0200}, author = {Ge, Qi and Wise, John}, biburl = {https://www.bibsonomy.org/bibtex/25e1a1287e46734d8c0409f665e45598b/miki}, description = {[1706.01467] On the effect of Lyman alpha trapping during the initial collapse of massive black hole seeds}, interhash = {78c3274f05a956c2612df433e896ffa8}, intrahash = {5e1a1287e46734d8c0409f665e45598b}, keywords = {Lya collapse trapping}, note = {cite arxiv:1706.01467}, timestamp = {2017-06-07T09:51:14.000+0200}, title = {On the effect of Lyman alpha trapping during the initial collapse of massive black hole seeds}, url = {http://arxiv.org/abs/1706.01467}, year = 2017 }