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Small Black Holes: Cloudy With a Chance of Better Visibility
Rambo Tribble writes "As reported by the BBC, astronomers are hoping to reap a black-hole-hunting windfall when a giant gas cloud passes through an area within our galaxy thought to contain numerous small black holes (abstract). When the cloud interacts with the black holes, the resultant emission of X-rays should allow scientists to finally confirm their existence. 'The idea is that as the cloud speeds past these small black holes — some slightly more massive than our Sun but just a few tens of km across — gas will spiral around them faster and faster, heating up to millions of degrees and emitting X-ray light. It is a bit like allowing a giant sink to empty through thousands of tiny drains and looking for any evidence of swirling water.'"
I have been trying to convince my wife that the dust around the house is an experiment and now I have something to show her!
It is a bit like allowing a giant sink to empty through thousands of tiny drains and looking for any evidence of swirling water.
It's a bit like dusting for fingerprints on a cosmic scale.
It's a bit like tossing handfuls of candy in a class room, then listening for quarreling and munching noises to detect school children.
It's a bit like rolling around in the grass then waiting for stings to discover fire ant mounds.
It's a bit like casting a net made out of fish and counting the holes to detect sharks.
It's a bit like shouting, "You're all fat and ugly" into the woman's bathroom then counting the "Screw You Jerk"s to see if you should wait to clean it.
It's a bit like making a bunch of posts on Slashdot to detect folks with mod points.
It's a bit like observing the expected effect black holes cause in various conditions to further confirm their existence.
The area around the central black hole is very crowded.
The black hole itself is probably about the "size" of the solar system (an event horizon a few light-hours in radius), there are multiple stars within light-weeks of the black hole itself, with orbital periods measured in years/decades, and some of them (S2, S14) come within several light-hours of the black hole, at velocities (relative to the black hole) of thousands of kilometers per second.
Any imaginary probe or lifeform magically teleported into the neighborhood would have one hell of a view in the moments before the radiation fried it to a crisp.
We have had "proof" for a long time in the mathematical sense, what has been more difficult is collecting enough evidence to say (beyond reasonable doubt) they exist in reality (the movie of stars orbiting the milky way's central black hole is my favorite "smoking gun"). I'm 54, when I went to school we were told black holes were "mathematical curiosities" that might exist in reality but nobody was sure, it was also claimed that it was impossible to observe an exo-planet. We live in "interesting times", science in general and astronomy in particular are experiencing a "golden age" that has it's roots in WW2 and is still gathering momentum.
Using maths to predict the existence of unobserved phenomena, and then looking for evidence of that phenomena in the real world is physics in a nutshell. It's also the reason astronomers no longer laugh at the big bang theory.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
No astronomers doubt the existance of black holes. Both black holes with masses comparable to stars, and supermassive black holes with millions to billions of solar masses are supported by a huge body of evidence. However, there is almost no evidence for black holes with masses in between these ranges, so-called intermediate mass black holes. But logically, they should exist - the way we think the supermassive black holes in the center of galaxies form is by a combination of accretion of matter and mergers of smaller black holes. Both of these mechanisms require supermassive black holes to grow from smaller progenitors.
What this article is about is an experiment to test the hypothesis that there is a high concentration of stellar- and intermediate-sized black holes near the center of the galaxy, waiting to merge with the central supermassive hole. So it is a test a model of the galactic structure, not the existance of black holes as such, though it could provide the first solid evidence of intermediate-mass black holes.