Lyman Alpha Signatures from Direct Collapse Black Holes. Dijkstra, M., Gronke, M., & Sobral, D. The Astrophysical Journal, 823(2):74, May, 2016. arXiv: 1602.07695![Lyman Alpha Signatures from Direct Collapse Black Holes [link]](https://bibbase.org/img/filetypes/link.svg "link")
Paper doi abstract bibtex `Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z\textasciitilde7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. We find that gravitational heating of the collapsing cloud gives rise to a Lya cooling luminosity of up to \textasciitilde 1e38(M_gas/1e6 Msun)\textasciicircum2 erg/s. The Lya production rate can be significantly larger during the final stages of collapse, but collisional deexcitation efficiently suppresses the emerging Lya flux. Photoionization by a central source boosts the Lya luminosity to L\textasciitilde1e43(M_BH/1e6 M_sun) erg/s during specific evolutionary stages of the cloud, where M_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitter at z\textasciitilde7, which is potentially associated with a DCBH. If CR7 is powered by a black hole, then its Lya flux alone requires that M_BH\textgreater 1e7 M_sun, which exceeds the mass of DCBHs when they first form. The observed width of the Lya spectrum favors the presence of only a low column density of hydrogen, log [N_HI/cm\textasciicircum-2]\textasciitilde19-20. The shape of the Lya spectrum indicates that this gas is outflowing. These requirements imply that if CR7 harbors a DCBH, then the physical conditions that enabled its formation have been mostly erased, which is in agreement with theoretical expectations.
@article{dijkstra_lyman_2016,
title = {Lyman {Alpha} {Signatures} from {Direct} {Collapse} {Black} {Holes}},
volume = {823},
issn = {1538-4357},
url = {http://arxiv.org/abs/1602.07695},
doi = {10.3847/0004-637X/823/2/74},
abstract = {`Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z{\textasciitilde}7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. We find that gravitational heating of the collapsing cloud gives rise to a Lya cooling luminosity of up to {\textasciitilde} 1e38(M\_gas/1e6 Msun){\textasciicircum}2 erg/s. The Lya production rate can be significantly larger during the final stages of collapse, but collisional deexcitation efficiently suppresses the emerging Lya flux. Photoionization by a central source boosts the Lya luminosity to L{\textasciitilde}1e43(M\_BH/1e6 M\_sun) erg/s during specific evolutionary stages of the cloud, where M\_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitter at z{\textasciitilde}7, which is potentially associated with a DCBH. If CR7 is powered by a black hole, then its Lya flux alone requires that M\_BH{\textgreater} 1e7 M\_sun, which exceeds the mass of DCBHs when they first form. The observed width of the Lya spectrum favors the presence of only a low column density of hydrogen, log [N\_HI/cm{\textasciicircum}-2]{\textasciitilde}19-20. The shape of the Lya spectrum indicates that this gas is outflowing. These requirements imply that if CR7 harbors a DCBH, then the physical conditions that enabled its formation have been mostly erased, which is in agreement with theoretical expectations.},
number = {2},
urldate = {2016-07-13},
journal = {The Astrophysical Journal},
author = {Dijkstra, Mark and Gronke, Max and Sobral, David},
month = may,
year = {2016},
note = {arXiv: 1602.07695},
keywords = {Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics},
pages = {74},
}
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Photoionization by a central source boosts the Lya luminosity to L\\textasciitilde1e43(M_BH/1e6 M_sun) erg/s during specific evolutionary stages of the cloud, where M_BH denotes the mass of the black hole powering this source. We predict that the width and velocity off-set of the Lya spectral line range from a few tens to few thousands km/s, depending sensitively on the evolutionary state of the cloud. We also compare our predictions to observations of CR7 (Sobral et al. 2015), a luminous Lya emitter at z\\textasciitilde7, which is potentially associated with a DCBH. If CR7 is powered by a black hole, then its Lya flux alone requires that M_BH\\textgreater 1e7 M_sun, which exceeds the mass of DCBHs when they first form. The observed width of the Lya spectrum favors the presence of only a low column density of hydrogen, log [N_HI/cm\\textasciicircum-2]\\textasciitilde19-20. The shape of the Lya spectrum indicates that this gas is outflowing. 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