It’s primarily those heavy elements that allow those gas clouds to cool and collapse, giving rise to stars with an average mass of 40% that of the Sun. Today, stars form from the collapse of gas clouds, made mostly of hydrogen and helium, but peppered with a small amount of heavier elements: oxygen, carbon, nitrogen, neon, silicon, sulfur, calcium, magnesium and iron, among others. The composition of the Universe, back before the very first stars ever formed, provides a tremendous clue that this might be possible. If the Universe could give birth to a seed black hole that was a few tens of thousands of solar masses just ~100 million years after the Big Bang, that would resolve the tension. Sure, a seed black hole of a few hundred solar masses at an epoch of ~100 million years after the Big Bang won’t quite do the job, but if we could make seed black holes that were just a hundred times more massive at that same, early epoch, that would provide a way out. However, there’s still a hope that this problem - or rather, this apparent problem - may simply turn out to result from ordinary, mundane, run-of-the-mill astrophysics. And yet, these stars only achieve temperatures of up to ~50,000 K, with white dwarfs, Wolf-Rayet stars, and neutron stars all getting hotter. The brightest of the stars found here are more than 8,000,000 times as luminous as our Sun. The largest group of newborn stars in our Local Group of galaxies, cluster R136, contains the most massive stars we’ve ever discovered: over 250 times the mass of our Sun for the largest. Or, perhaps our picture is way off base, and the Universe was actually born with black holes that formed before any stars ever could: a set of primordial black holes.Perhaps we have the seed-size all wrong, and that larger cosmic seeds are possible, driven by processes like structure formation or a much greater initial mass for the heaviest stars.Perhaps we’ve got the seed-size and time right, but the growth wrong, and that black holes masses grow faster than we realize.In the recent past, many ideas have been floated to explain why, but they all fall into three categories. These earliest supermassive black holes have grown larger than we expect that they should have given what we know about the Universe and how the laws of physics work over time. In other words, something doesn’t add up. It’s as though some of those 5-year-olds are as tall as full-grown basketball players, reaching sizes that we didn’t expect them to reach until they were much, much older. When we do this, we find that we’re not just seeing the proverbial 5-year-old humans with a variety of heights, weights, foot sizes, and other properties. We’ve now found quasars with supermassive black holes anywhere from 500 million to slightly over 1 billion solar masses that date back to a time where the Universe was just around ~700 million years old: a mere 5% of its current age. Wang, AAS237)Īnd this is where the puzzle arises. Examining quasar-galaxy hybrids may hold the key to unraveling this mystery. Either these black holes start off bigger than our theories expect, form earlier than we realize, or they grow faster than our present understanding allows to achieve the mass values we observe. If you begin with an initial, seed black hole when the Universe was only 100 million years old, there’s a limit to the rate at which it can grow: the Eddington limit. Although there are, of course, uncertainties here, we all agree that it takes tens of millions of years for the very first stars to form, and that the first major wave of star formation in the Universe won’t occur until between 100 and 200 million years have elapsed. In other words, at the start of the hot Big Bang, even the densest regions out there contain only ever-so-slightly more mass than the average.Īs a result, along with the physics of how matter and radiation evolve in the early Universe, we can calculate how long we expect it will take for even the initially most dense regions to collect enough matter to form the first collapsed objects: stars and black holes among them. and all 1000 regions had between 99.988% and 100.012% of the average density.about 997 regions had between 99.991% and 100.009% of the average density,.about 954 regions had between 99.994% and 100.006% of the average density,.

about 683 regions had between 99.997% and 100.003% of the average density,.

Ultramassive black hole