Astronomers Find First Ever Rogue Black Hole Adrift In the Milky Way (scientificamerican.com) 53
Scientific American reports:
These are boom times for astronomers hunting black holes. The biggest ones — supermassive black holes that can weigh billions of suns — have been found at the centers of most every galaxy, and we have even managed to image one. Meanwhile, researchers now routinely detect gravitational waves rippling through the universe from smaller merging black holes. Closer to home, we have witnessed the dramatic celestial fireworks produced when the Milky Way's own supermassive black hole and its more diminutive cousins feed on gas clouds or even entire stars. Never before, though, have we seen a long-predicted phenomenon: an isolated black hole drifting aimlessly through space, born and flung out from the collapsing core of a massive star.
Until now.
Scientists have announced the first-ever unambiguous discovery of a free-floating black hole, a rogue wanderer in the void some 5,000 light-years from Earth. The result, which appeared January 31 on the arXiv preprint server but has not yet been peer-reviewed, represents the culmination of more than a decade of ardent searching. "It's super exciting," says Marina Rejkuba from the European Southern Observatory in Germany, a co-author on the paper. "We can actually prove that isolated black holes are there." This discovery may be just the start; ongoing surveys and upcoming missions are expected to find dozens or even hundreds more of the dark, lonely travelers. "It's the tip of the iceberg," says Kareem El-Badry from the Harvard-Smithsonian Center for Astrophysics, who was not involved in the paper....
The odds of seeing such an event for an isolated black hole were slim, but given that millions of stellar-mass black holes are predicted to be drifting through our galaxy, some might turn up in sufficiently broad and deep surveys of the sky.... This black hole's mass offers further evidence that astrophysicists' formation models are correct — that solitary black holes can rise from the ashes of especially hefty stellar progenitors.... Rogue stellar-mass black holes, long predicted but only now observationally confirmed, might well be sufficiently common in our galaxy to support demographic studies of their population. Pinning down their true abundance, masses and other properties could shore up our still-incomplete theories of stellar evolution — or reveal important new gaps in our understanding.
"If confirmed, this is a very exciting discovery!" adds the astronomy column at Syfy.com. "We know those black holes are out there, and this research points to how we can find them."
The precise astrometry was partly performed using the Hubble Space Telescope over a six-year interval, according to the research paper.
Until now.
Scientists have announced the first-ever unambiguous discovery of a free-floating black hole, a rogue wanderer in the void some 5,000 light-years from Earth. The result, which appeared January 31 on the arXiv preprint server but has not yet been peer-reviewed, represents the culmination of more than a decade of ardent searching. "It's super exciting," says Marina Rejkuba from the European Southern Observatory in Germany, a co-author on the paper. "We can actually prove that isolated black holes are there." This discovery may be just the start; ongoing surveys and upcoming missions are expected to find dozens or even hundreds more of the dark, lonely travelers. "It's the tip of the iceberg," says Kareem El-Badry from the Harvard-Smithsonian Center for Astrophysics, who was not involved in the paper....
The odds of seeing such an event for an isolated black hole were slim, but given that millions of stellar-mass black holes are predicted to be drifting through our galaxy, some might turn up in sufficiently broad and deep surveys of the sky.... This black hole's mass offers further evidence that astrophysicists' formation models are correct — that solitary black holes can rise from the ashes of especially hefty stellar progenitors.... Rogue stellar-mass black holes, long predicted but only now observationally confirmed, might well be sufficiently common in our galaxy to support demographic studies of their population. Pinning down their true abundance, masses and other properties could shore up our still-incomplete theories of stellar evolution — or reveal important new gaps in our understanding.
"If confirmed, this is a very exciting discovery!" adds the astronomy column at Syfy.com. "We know those black holes are out there, and this research points to how we can find them."
The precise astrometry was partly performed using the Hubble Space Telescope over a six-year interval, according to the research paper.
Millions inside our galaxy? (Score:2)
So what are the odds of one of them wandering close enough to our solar system to cause some sort of punk? And would we have a warning? And nothing we could do about it...
Dark matter candidate (Score:5, Interesting)
So what are the odds of one of them wandering close enough to our solar system to cause some sort of punk? And would we have a warning? And nothing we could do about it...
I don't think this is the interesting part of the announcement.
Many people have wondered whether dark matter could be explained by (a bunch of) black holes.
If this were true, the holes would occasionally pass near, or in front of, other stars and show gravitational deflection as viewed from Earth. How often this happens depends on the black hole density, their average size, how long you look, and so on. Astronomers have been searching for deflections, and certain parameter combinations have been ruled out, but not all possible combinations (yet).
The preprint in the OP describes a deflection event detected by Hubble that shows an object of 7-ish solar masses emitting no light. This is more massive than a dwarf or neutron star, so is assumed to be a black hole.
This can help put an upper/lower bound on the density and mass of rogue black holes, and help determine whether they can account for dark matter.
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Yes. And the telescopes get better with time. If you have a single clear detection, you now know what to look for with some real world data to help. So in time we will be able to detect very many of these lensing events and pull the bounds in and therefore be able to establish to what extent black holes contribute to the unseen matter.
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For objects that are far away, the time delta needed to "see" the object moving is impractical. Even this "close by" observation took six years. So the "better" telescopes are for looking further.
In terms of t
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It's moving at 45 km/s (FTF.abstract) across our line of sight ; we don't have an estimate of the radial (towards/ away) component of motion. 45 km/s is the minimum speed of the object.
That sounds fast. It's quite similar to the average speed of Mercury in it's orbit (47.4 km/s) ; pretty speedy on a terrestrial scale ; pretty pedestrian on a galactic scale.
I make it 12.1 million years, if it were coming this way, which it's
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I'd better improve my diet and exercise more if I ever want to see it collide with the sun.
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Re: Millions inside our galaxy? (Score:1)
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So what are the odds of one of them wandering close enough to our solar system to cause some sort of punk?
Something out there has obviously pulled the outer eliptic out of alignment and if it was a brown dwarf, we likely would've found it by now; you do the math.
Re: Millions inside our galaxy? (Score:2)
They are very far away and would take a long time to reach us. If any black holes are very close they would have peturbed orbits of outer planets and comets for centuries, tipping us off. Any if they are really close, like within the oort cloud or closer, the particles from solar winds and dust would have maybe for an interesting x-ray light show.
A extinction level asteroid is more likely. Large enough to kill us, but small, cold and dark making it difficult to spot. We would not have a lot of warning, mont
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> Take heart that we'd never see our Sun die. We'd be flung far out of the Solar System before that came to pass.
Now that's reassuring. Shot out of the solar system in some random direction, a rogue planet wandering into the great emptiness. The only possible energy source fusion but that will be just 20 years from getting ready like it ever was...
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I think that would be a good time to warm the planet up by burning all the CO2-generating fuel we can.
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Wouldn't do much good without sunlight to heat the ground and do the greenhouse thing. Would slightly slow the cooling. Once the icecaps reach the equator, humidity would drop to close to zero with water vapor being the major greenhouse gas, things would get cold.
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Yes, Geo-thermal would soon be the only practicable means of energy. Fossil fuels would get awfully hard to extract fairly quick and even nuclear usually depends on water to operate.
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Geothermal. Read somewhere about a million years for the oceans to mostly freeze solid. If the Moon came along for the ride, the tidal forces would help too.
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Considering they're stellar mass and there are around a billion stars in the galaxy, the odds of a black hole messing with our solar system would be on the order of a thousandth the odds of a regular star doing the same thing. Stars do disturb the Oort cloud every once in a while and send us more comets, so that's about as much as you'd expect from such an encounter. Merely being a black hole doesn't make the object more dangerous to us if it's not more massive than a star.
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Considering they're stellar mass and there are around a billion stars in the galaxy,
Uh.. erm... Current estimates are 100 to 400 billion. [nasa.gov]
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Mostly red dwarfs which would have to get that much closer to perturb things.
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Where?
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So what are the odds of one of them wandering close enough to our solar system to cause some sort of punk?
Millions of black holes, hundreds of billions of stars. A stellar mass black hole exerts the same gravity as a stellar mass sun.. So... I'd say the odds are very much against us ever having to deal with one.
DART probably won't help much with this one (Score:2)
Just suppose the rogue black hole started coming our way, the DART technology NASA is trying out on an asteroid won't be of much help. How exactly would an impactor even make a dent in a super massive black hole? Is there even a surface to hit beyond the event horizon? The inertia of the black hole is pretty much infinite compared to anything we could throw at it.
https://solarsystem.nasa.gov/r... [nasa.gov]
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"The inertia of the black hole is pretty much infinite compared to anything we could throw at it."
Pretty much. These are objects that can tear apart the sun simply by passing by. It's beyond hubris to think we're going to affect it.
Theoretically, if we put enough mass near it, while it was far enough away, gravity would deflect it, but what's enough mass, and how far away would it need to be placed to have enough effect? (depends on the course, mass, and speed of the black hole of course) but even a near m
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Just suppose the rogue black hole started coming our way, the DART technology NASA is trying out on an asteroid won't be of much help. How exactly would an impactor even make a dent in a super massive black hole? Is there even a surface to hit beyond the event horizon? The inertia of the black hole is pretty much infinite compared to anything we could throw at it.
https://solarsystem.nasa.gov/r... [nasa.gov]
Most likely it would be easier to move the 1 solar mass solar system out of the approaching 7 solar mass blackhole's way than vica versa. I'd go with turning all of the asteroids into a rotating conductive iron ring around the sun to steer the solar wind magnetically, might have to throw in the inner planet's iron cores too.
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Been reading ... ummm, "Ringworld Engineers"? recently?
Don't forget to build an attitude jet system, to keep it centred on the Sun. And is iron strong enough to support the tension of spinning it at an orbital speed of around 25km/s? (For a mid-belt position.)
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I did read Ringworld a long time ago.
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Danger (Score:2)
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no real danger, anything coming "close" to Sun, within light year (63K AU), would just have the most likely mutual interaction of the two bodies flinging each other away from each other. The planets would go along for the ride with the sun. Likelihood of black hole passing through planets at 40 AU or less and disturbing orbits is about zero. Space is just too big.
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Does raise the question of how close a 7 solar mass object has to get to perturb our orbit. I guess at that point there would also be a lot of other objects perturbed and visiting the inner solar system.
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We are probably more likely to have a close encounter with another star. Other than maybe having an earlier warning, there's not much that can be done about such either. But compared to all the space risks, both are small.
So close (Score:2)
The article was so close in their desciption. They could have used:
A free-floating, full-torso dense apparition.
Re: So close (Score:1)
The white noise emissions were later unscrambled (Score:1)
Huh? (Score:2)
I would argue (Score:2)
It's hard to define the "weight" of a black hole. They do, however, have a lot of mass.
Given this paper hasn't even been peer reviewed or accepted for publication, it might be premature to get too excited about this.
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Don't forget to post the link to your paper when it goes up.
(For the audience - with 60-odd institutions represented by the I'don't-know-how-many-collaborators, including having got the proposal through review to get the observing time on the HST, this has probably been through many rounds of review already. It has been submit
So many black hole mergers (Score:2)
I find it amazing that so many black holes are seen merging. If we think of a slightly different collision, that of two galaxies, there is a high likelihood that _no_ stars will collide -- there's just so much space between neighbouring stars.
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But once a binary pair of black holes is formed either from two paired stars that collapsed, or by capture, decay of the orbit by radiating energy away as gravitational waves makes merger a certainty. So all the binary black hole pairs that ever existed merged or will merge.
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As Iggymanz points out, the origin of massive stars (and hence their derived black holes) is far from random, involving the interactions in a collapsing molecular cloud. Comparing this to the random interaction of unrelated stars in a galactic merger is inappropria
Near zero chance of a planet falling into one (Score:2)
To fall into a back hole there is a very narrow zone in it's flight path as far as sucking up planets while flying through a solar system. The chances of it actually flying through a solar system is astronomical. More likely and destructive to earth and life on any planet is a black holes ability to disturb orbits even slightly which is far far far more likely even though the chance of it happening itself is so unlikely. More likely are solar systems as a whole changing trajectory very slightly very much li
"Floating" and "adrift" are strange wording... (Score:2)
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I also noted the wording and found it odd. It is possible that they move relative to the stars in its neighborhood. But if so I would think that the mass of the black hole makes it much more likely that the black hole is relatively speaking stationary and the other stars move around it with far more velocity.
In my own personal view of the universe, black holes has such a steep gravity gradient that it is much closer to the center (of the universe) and drags on the expanding space around it in such a way tha
Maneuvers (Score:2)
These are boom times for astronomers hunting black holes.
Don't get too cocky. It knows some maneuvers -- like listing lazily to the left.