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Hidden secrets of the universe! How can a black hole seed with a mass of one million solar masses be generated in a high redshift region?
In the initial stages of the universe, the formation of black holes has always been a fascinating subject. Recent scientific research has pointed out that direct collapse black holes (DCBHs) are important black hole seeds formed in high redshift regions, and their masses can be as high as one million solar masses. This scientific breakthrough not only gives us a deeper understanding of the history of the universe, but also redefines the formation mechanism of high-quality black holes.
The formation process of direct collapse black holes
The formation of direct collapse black holes occurs approximately in the redshift range z=15 to 30, which means that when the universe was only 100 to 200 million years old, the conditions in the universe were particularly suitable for the condensation of large-scale matter .
The formation of these black holes is different from the black hole seeds that originated from the first stars (i.e. Population III stars), but is directly driven by a kind of gravitational instability.
Before these black holes can form, the gas must meet a series of specific conditions, such as being metal-free (containing only hydrogen and helium) and having enough Lyman-Werner photon flux to destroy the hydrogen molecules, preventing the gas from cooling and Fragmented. Such an environment prompts the gravitational collapse of the gas cloud, ultimately leading to the formation of a black hole at the extremely high density of matter at its core.
A rare number of direct collapse black holes
Despite theoretical support for DCBHs, we currently know that they are very rare in the high-redshift universe. According to the latest cosmic simulations, the conditions for the formation of such black holes are very harsh, so their number density is predicted to be only about 1 per cubic gigapasec at most. In the most optimistic scenario, this amount could reach about 100,000 per cubic gigaparasec.
Observation and discovery
With the advancement of science and technology, astronomers are becoming more and more active in searching for DCBH. Since 2016, a research team from Harvard University has been using the Hubble Space Telescope and the Chandra X-ray Observatory to look for clues about such black holes. Recently, they discovered two candidates that match predicted spectral features in data in the high redshift range z > 6.
These black holes are characterized by a significant excess of infrared radiation, which is more obvious than other high-redshift objects.
Differences from primordial black holes and stellar collapse black holes
It is important to note that there are fundamental differences between DCBHs and primordial black holes and stellar collapse black holes. While primordial black holes form from a direct collapse of energy, DCBHs result from the collapse of unusually dense regions of gas.
During the formation process of primordial black holes, they do not undergo any intermediary processes from stars, so we generally do not classify black holes produced by the collapse of Population III stars as "direct fragile decomposition."
Future research directions
With the launch of the James Webb Space Telescope, observations of these candidate black holes will be further deepened, and we will be able to confirm their nature and existence more effectively. In any case, the exploration of DCBH is still full of challenges and mysteries, which not only brings us new questions about cosmology, but also stimulates our thinking about the formation and evolution of the universe.
These cutting-edge studies reveal an important question: How many mysterious phenomena remain to be uncovered in this infinite universe?
