科维理宇宙物理学与数学研究所认为这些暗物质是由原始黑洞组成的。
https://phys.org/news/2020-12-primordial-black-holes-dark-multiverse.html
来自科维理宇宙物理与数学研究所的研究人员一直在对可能形成于早期宇宙的黑洞进行研
究，这些所谓的原始黑洞被认为是在恒星和星系诞生之前形成的。原始黑洞可能是全部或
部分暗物质形成的原因，也是我们银河系中心和其他地方发现的一些观测到的引力波信号
和超大质量黑洞的成因。
研究人员还有理论认为，当原始黑洞与中子星碰撞并摧毁中子星，释放出富含中子的物质
时，它们可能在重元素的合成中发挥作用。最有趣的理论是，暗物质是由原始黑洞组成的
。
研究人员在研究过程中，从早期宇宙中寻找有关原始黑洞的线索。他们认为早期宇宙的密
度非常大，任何超过50%的正密度波动都会产生黑洞。早期宇宙中的一些过程可能为黑洞
的形成创造了合适的条件。研究小组提出的另一个令人激动的前景是，原始黑洞有可能从
膨胀期间创造的”婴儿宇宙”中形成。历经一个快速膨胀的时期，被认为是我们今天观察
到的星系和星系团的原始形态。
在膨胀期间，”婴儿宇宙”可能会从我们的宇宙中分支出来，创造出一个子宇宙，最终它
会崩溃，小体积中释放的大量能量导致黑洞的形成。根据爱因斯坦的引力理论，宇宙可以
存在于内部和外部的观察者看来不同的状态。内侧的观察者会看到一个膨胀的宇宙，而外
侧的观察者（比如我们）会看到它是一个黑洞。
我们可以把大大小小的”婴儿宇宙”看作是原始黑洞，在黑洞的事件视界后面隐藏着多个
宇宙的底层结构。在论文中，研究人员描述了原始黑洞形成的场景，并表明可以利用夏威
夷望远镜上的精密镜头发现来自 “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))