%0 Generic %1 dijkstra2016lyman %A Dijkstra, Mark %A Gronke, Max %A Sobral, David %D 2016 %K black collapse direct hole lya %T Lyman Alpha Signatures from Direct Collapse Black Holes %U http://arxiv.org/abs/1602.07695 %X `Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z~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 ~ 1e38(M_gas/1e6 Msun)^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~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~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> 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^-2~19-20. 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.

@misc{dijkstra2016lyman, abstract = {`Direct collapse black holes' (DCBHs) provide possible seeds for supermassive black holes that exist at redshifts as high as z~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 ~ 1e38(M_gas/1e6 Msun)^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~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~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> 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^-2]~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.}, added-at = {2016-02-26T09:50:25.000+0100}, author = {Dijkstra, Mark and Gronke, Max and Sobral, David}, biburl = {https://www.bibsonomy.org/bibtex/2231c5c284fccab76d8992f17a8dccf30/miki}, description = {[1602.07695] Lyman Alpha Signatures from Direct Collapse Black Holes}, interhash = {d4ea1ddeae229f59dd79f0ce6530c5f1}, intrahash = {231c5c284fccab76d8992f17a8dccf30}, keywords = {black collapse direct hole lya}, note = {cite arxiv:1602.07695Comment: 16 pages, 7 figures, submitted to ApJ following revision based on referee report}, timestamp = {2016-02-26T09:50:25.000+0100}, title = {Lyman Alpha Signatures from Direct Collapse Black Holes}, url = {http://arxiv.org/abs/1602.07695}, year = 2016 }