Impact of radiation backgrounds on the formation of massive black holes

The presence of supermassive black holes (SMBHs) of a few billion solar masses at very high redshift, has motivated us to study how these massive objects formed during the first billion years after the Big Bang. A promising model that has been proposed to explain this, is the direct collapse of protogalactic gas clouds. In this scenario, very high accretion rates are needed to form massive objects early on, and the suppression of i cooling is important in regulating the fragmentation. Recent studies have shown that if we use a strong radiation background, the hydrogen molecules are destroyed, favoring the high accretion rates and therefore producing objects of very high mass. In this work, we study the impact of UV radiation fields in a primordial gas cloud using the recently coupled code GRADSPH-KROME for the modeling of gravitational collapse, including primordial chemistry to explore the fragmentation in AU scales and hence the formation of thr first SMBHs. We found that, to suppress the formation of i, a very high value of is required (). As shown in a previous work, such strong radiation backgrounds are very rare, so that the direct collapse may be difficult to achieve. Therefore, this method could hardly explain the formation of the first SMBHs.