What came into existence first: black holes or galaxies? COSMOLOGY
Galaxies, or the ancestors of galaxies as we know them today, likely came first. More specifically, stars – first-generation stars – likely formed first and produced the first ‘artificial’ light in the universe, before any black hole could form.
The first generation of stars likely formed just a few hundred million years after the Big Bang, hosted by dark matter mini-halos. We still don’t know what dark matter is, but we surely think we owe our very existence to it. Without dark matter stars would not be able to form, and the universe as a whole would never witness the invention of chemistry by the supernovae explosions of the first stars and the subsequent possibility of biology that followed.
In principle the first black holes – with masses of a few Suns – were actually a result of what was left of massive first-generation stars after they exploded and produced some of the oxygen we are breathing right now.
Interestingly enough, it is possible that some of the first supermassive black holes – with masses of almost one million-times the Sun – could have formed by a direct collapse of clouds of gas, essentially without ever becoming a star. However, it turns out that you need stars or a galaxy in relatively close proximity in the very early universe to give rise to the conditions necessary for these extraordinary events to happen. All in all, we think that first-generation stars came first, but rapidly led to the formation of the first black holes and the first supermassive black holes. Dr David Sobral is a reader in astrophysics at Lancaster University in England, researching the primitive universe and how the first galaxies formed