Largest black hole collision ever detected

Jul 27, 2020
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Quoting from the article:

"The missing nine suns’ worth of matter got converted into energy in the collision, shaking the universe hard enough for LIGO and Virgo to detect and interpret. And that's how scientists learned that 85 solar mass black holes and monster 142 solar mass black holes can exist at all."

end quote

Most theories suggest that such large black holes should not exist from core collapse SNs. But they certainly can exist, and in large numbers, if they are primordial black holes (PBHs). These could have formed in the very early stages of the BB when matter was at a high density and just starting to expand. Many consider this unlikely, but the current data may suggest otherwise.

It is hypothesized that population III stars, supposedly the earliest stars to form, were massive and formed many large BHs that later merged, ultimately creating super massive black holes (SMBHs). Many believe that this is the only way SMBHs could form - by way of a stellar object collapsing into a black hole, and these merging into ever larger BHs. These theories do not allow for SMBHs much earlier than about 1 billion years after the BB. However, at least two quasars with SMBHs much earlier than this have already been documented, and many galaxies have been seen even earlier. It would appear that something may be wrong with the basic "consensus" concept of how all BHs form.

Enter the PBHs (1). The same mass-collapse mechanism which creates stellar mass BHs could occur without a stellar intermediate. This is referred to as a Direct Collapse Black Hole, and their size could be highly variable since they do not rely on stellar intermediates. Their time of formation however would be limited to the extreme mass density which occurred immediately following the BB and before sufficient expansion had occurred to prevent their formation. Just like population III star formation, only PBHs do not form from an intermediate star, they simply collapse directly into a BH due to the high density variations in the BB's expanding matter.

The presence of black holes as large as those observed in this merger is going to have a lot of people wondering about how they could have formed. Previous mergers have already revitalized interest in PBHs for some theorists (2, 3). This one might nudge a few more in that direction .


(1)
(2) https://www.sciencemag.org/news/2020/09/middleweight-black-holes-finally-found-they-pose-puzzle

(3) https://www.nature.com/articles/d41586-020-02524-w
 
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