Torn-apart star gives strongest evidence yet of mysterious black hole

[Judi Lynn]

Torn-apart star gives strongest evidence yet of mysterious black hole
Scientists say mid-size black holes are the missing link in their understanding of black hole evolution.

By Sara Rigby, PA Science
02nd April, 2020 at 10:30

Astronomers say they have found the strongest evidence yet of an elusive type of black hole in space.

These mid-sized objects, known as intermediate-mass black holes, are harder to find but new data from the Hubble Space Telescope suggests there is one tucked away inside a dense star cluster. Proof has been long-sought by scientists as the missing link in their understanding of black hole evolution.

They are difficult to uncover because they are smaller and less active than supermassive black holes, as well as having a weaker gravitational pull, meaning they can’t be easily spotted gobbling up other stars. Astronomers were therefore left to wait for the rare moment one might tear apart a star that came too close.

“Intermediate-mass black holes are very elusive objects, and so it is critical to carefully consider and rule out alternative explanations for each candidate,” said Dacheng Lin, principal investigator of the study, from the University of New Hampshire. “That is what Hubble has allowed us to do for our candidate.”

More:
https://www.sciencefocus.com/news/torn-apart-star-gives-strongest-evidence-yet-of-mysterious-black-hole/

[PoindexterOglethorpe]

1. Oh, my.

That is fascinating.

[muriel_volestrangler]

2. Here's a nice piece by the presenter of the BBC's "The Sky at Night"

Things are not always so quiet in the galactic centre, however. An object called G2, which seems to be a dust-enshrouded star, was observed surviving a close passage in 2014. And the recent discovery of radio echoes of past activity by a radio telescope called MeerKAT suggests that our galaxy’s central black hole went on what I suppose we should call a violent feeding frenzy a few million years ago. Such episodes may be caused by disturbances in the galaxy’s disk, funnelling material towards the centre and feeding the black hole, and they indicate that understanding the history of galaxies relies on understanding the behaviour of their black holes.

This is a problem, because we don’t understand the black holes themselves. We know that small black holes can be created in the supernovae that mark the death of massive stars, but a black hole produced that way would probably have a maximum mass of maybe fifty suns, a long way from the million-solar-mass supermassive examples at the centres of galaxies. In the 14 billion years since the Big Bang, there hasn’t been enough time for a black hole that starts off small to consume enough material to grow up to be the size of the Milky Way’s supermassive black hole.

The mystery has been compounded by the apparent absence of intermediate-mass black holes, the missing link between the small and supermassive states. Astronomers have been looking for a long time, and this week their search may have borne fruit. In 2006, X-ray telescopes picked up a flare, a burst of radiation that matched predictions of what would happen if a remote star were ripped apart by a medium-sized black hole, but astronomers couldn’t be sure that the burst didn’t come from a more local source. The orbiting Hubble Space Telescope has now pinpointed the origin of the flare, which comes from a cluster on the outskirts of a distant galaxy.

Such a cluster may be the remnant of a dwarf system, a stepping stone between primordial matter and modern galaxies like the Milky Way. If so, then it may have a similarly underdeveloped black hole, meaning that in this new source we see the long distant past of our own system and the black hole at its centre. This kind of astrophysics isn’t unlike archaeology, as it involves the slow sifting of ancient remnants in order to piece together a complex story of the past.

https://www.lrb.co.uk/blog/2020/april/black-holes-and-revelations