Lyman alpha signatures from direct collapse black holes

摘要: `Direct collapse black holes' (DCBHs) provide possible seeds for supermassive holes that exist at redshifts as high z~7. We study Lyman Alpha (Lya) radiative transfer through simplified representations of the DCBH-scenario. find gravitational heating collapsing cloud gives rise to a Lya cooling luminosity up ~ 1e38(M_gas/1e6 Msun)^2 erg/s. The production rate can be significantly larger during final stages collapse, but collisional deexcitation efficiently suppresses emerging flux. Photoionization by central source boosts L~1e43(M_BH/1e6 M_sun) erg/s specific evolutionary cloud, where M_BH denotes mass hole powering this source. predict width and velocity off-set spectral line range from few tens thousands km/s, depending sensitively on state cloud. also compare our predictions observations CR7 (Sobral et al. 2015), luminous emitter z~7, which is potentially associated with DCBH. If powered hole, then its flux alone requires M_BH> 1e7 M_sun, exceeds DCBHs when they first form. observed spectrum favors presence only low column density hydrogen, log [N_HI/cm^-2]~19-20. shape indicates gas outflowing. These requirements imply if harbors DCBH, physical conditions enabled formation have been mostly erased, in agreement theoretical expectations.