died as DCBHs of 31,000 and 40,000 solar masses. Demography Direct collapse black holes are generally thought to be extremely rare objects in the high-redshift Universe, because the three fundamental conditions for their formation (see above in section Formation) are challenging to be met all together in the same gas cloud. Current cosmological simulations suggest that DCBHs could be as rare as only about 1 per cubic gigaparsec at redshift 15. The prediction on their number density is highly dependent on the minimum flux of Lyman-Werner photons required for their formation and can be as large as DCBHs per cubic gigaparsec in the most optimistic scenarios. Detection In 2016, a team led by Harvard University astrophysicist Fabio Pacucci identified the first two candidate direct collapse black holes, using data from the Hubble Space Telescope and the Chandra X-ray Observatory. The two candidates, both at redshift , were found in the CANDELS GOODS-S field and matched the spectral properties predicted for this type of astrophysical sources. In particular, these sources are predicted to have a significant excess of infrared radiation, when compared to other categories of sources at high redshift. Additional observations, in particular with the upcoming James Webb Space Telescope, will be crucial to investigate the properties of these sources and confirm their nature. See also Primordial black hole References Astronomy Astrophysics Physical cosmology Galaxies Black holes Supermassive black holes Theory of relativity