科維理宇宙物理學與數學研究所認為這些暗物質是由原始黑洞組成的。
https://phys.org/news/2020-12-primordial-black-holes-dark-multiverse.html
來自科維理宇宙物理與數學研究所的研究人員一直在對可能形成於早期宇宙的黑洞進行研
究，這些所謂的原始黑洞被認為是在恆星和星系誕生之前形成的。原始黑洞可能是全部或
部分暗物質形成的原因，也是我們銀河系中心和其他地方發現的一些觀測到的引力波信號
和超大質量黑洞的成因。
研究人員還有理論認為，當原始黑洞與中子星碰撞並摧毀中子星，釋放出富含中子的物質
時，它們可能在重元素的合成中發揮作用。最有趣的理論是，暗物質是由原始黑洞組成的
。
研究人員在研究過程中，從早期宇宙中尋找有關原始黑洞的線索。他們認為早期宇宙的密
度非常大，任何超過50%的正密度波動都會產生黑洞。早期宇宙中的一些過程可能為黑洞
的形成創造了合適的條件。研究小組提出的另一個令人激動的前景是，原始黑洞有可能從
膨脹期間創造的”嬰兒宇宙”中形成。歷經一個快速膨脹的時期，被認為是我們今天觀察
到的星系和星系團的原始形態。
在膨脹期間，”嬰兒宇宙”可能會從我們的宇宙中分支出來，創造出一個子宇宙，最終它
會崩潰，小體積中釋放的大量能量導致黑洞的形成。根據愛因斯坦的引力理論，宇宙可以
存在於內部和外部的觀察者看來不同的狀態。內側的觀察者會看到一個膨脹的宇宙，而外
側的觀察者（比如我們）會看到它是一個黑洞。
我們可以把大大小小的”嬰兒宇宙”看作是原始黑洞，在黑洞的事件視界後面隱藏着多個
宇宙的底層結構。在論文中，研究人員描述了原始黑洞形成的場景，並表明可以利用夏威
夷望遠鏡上的精密鏡頭發現來自 “多元宇宙”的黑洞。
https://imgur.com/BoxVWId https://imgur.com/1l3ab29
One exciting possibility is that primordial black holes could form from the
"baby universes" created during inflation, a period of rapid expansion that
is believed to be responsible for seeding the structures we observe today,
such as galaxies and clusters of galaxies. During inflation, baby universes
can branch off of our universe. A small baby (or "daughter") universe would
eventually collapse, but the large amount of energy released in the small
volume causes a black hole to form.
An even more peculiar fate awaits a bigger baby universe. If it is bigger
than some critical size, Einstein's theory of gravity allows the baby
universe to exist in a state that appears different to an observer on the
inside and the outside. An internal observer sees it as an expanding
universe, while an outside observer (such as us) sees it as a black hole. In
either case, the big and the small baby universes are seen by us as
primordial black holes, which conceal the underlying structure of multiple
universes behind their "event horizons." The event horizon is a boundary
below which everything, even light, is trapped and cannot escape the black
hole.
In their paper, the team described a novel scenario for PBH formation and
showed that the black holes from the "multiverse" scenario can be found using
the Hyper Suprime-Cam (HSC) of the 8.2m Subaru Telescope, a gigantic digital
camera—the management of which Kavli IPMU has played a crucial role—near
the 4,200 meter summit of Mt. Mauna Kea in Hawaii. Their work is an exciting
extension of the HSC search of PBH that Masahiro Takada, a Principal
Investigator at the Kavli IPMU, and his team are pursuing. The HSC team has
recently reported leading constraints on the existence of PBHs in Niikura,
Takada et. al. (Nature Astronomy 3, 524-534 (2019))