There’s nothing quite like a cheeky snooze after a large, indulgent meal.
And it turns out we’re not alone – as a massive black hole has been spotted taking a ‘nap’ after overeating.
An international team of astronomers, led by the University of Cambridge, used the James Webb Space Telescope to detect a black hole in the early universe, just 800 million years after the Big Bang.
The black hole is huge – 400 million times the mass of our Sun – making it one of the most massive black holes discovered by Webb at this point in the universe’s development.
It is so enormous that it makes up roughly 40 per cent of the total mass of its host galaxy.
In comparison, most black holes in the local universe are roughly 0.1 per cent of their host galaxy mass.
However, despite its gigantic size, this black hole is eating, or accreting, the gas it needs to grow at a very low rate – about 100 times below its theoretical maximum limit – making it essentially dormant.
And this discovery has challenged existing models of how black holes develop.
The researchers say the most likely scenario is that black holes go through short periods of ultra-fast growth, followed by long periods of dormancy.
Professor Roberto Maiolino, one of the study’s authors, said: ‘It’s possible that black holes are ‘born big’, which could explain why Webb has spotted huge black holes in the early universe.
‘But another possibility is they go through periods of hyperactivity, followed by long periods of dormancy.
‘It sounds counterintuitive to explain a dormant black hole with periods of hyperactivity, but these short bursts allow it to grow quickly while spending most of its time napping.’
Further analysis suggests that black holes such as this one likely eat for five to 10 million years and sleep for about 100 million years.
When black holes are ‘napping’, they are far less luminous, making them more difficult to spot, even with highly-sensitive telescopes such as Webb.
Black holes cannot be directly observed.
Instead they are detected by the tell-tale glow of a swirling accretion disc, which forms near the black hole’s edges.
The gas in the accretion disc becomes extremely hot and starts to glow and radiate energy in the ultraviolet range.
The team said this new discovery could be the tip of a much larger iceberg, if black holes in the early universe spend most of their time in a dormant state.
‘It’s likely that the vast majority of black holes out there are in this dormant state – I’m surprised we found this one, but I’m excited to think that there are so many more we could find,’ Professor Maiolino added.
Their findings were published in the journal Nature.
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