For years, astronomers have been puzzled by why the biggest black holes in the universe have been growing much more slowly over the past 10 billion years. Now, a new study offers a potential solution to this astrophysical enigma: They're starved for gas.
Supermassive black holes (SMBHs) have immense gravitational appetites that allowed them to grow to many millions or billions of times the mass of the sun at surprisingly rapid rates in the first few billion years after the Big Bang. However, SMBHs have been growing ever more slowly since the period known as "cosmic noon," when the universe was less than a quarter of its current age.
