Possible detection of a black hole with a mass that was thought to be impossible

https://www.quantamagazine.org/possible-detection-of-a-black-hole-so-big-it-should-not-exist-20190828/

by theafh • 7 years ago

189 96 7 years ago

brianberns2• 7 years ago

The title is misleading. Just to be clear, theory predicts that blacks holes shouldn't be created between 50 and 130 solar masses, but there are plenty of black holes >130 solar masses. This is just an observation of a black hole that falls inside the supposedly "forbidden" range.

jacobush3• 7 years ago

I agree except the word "just". It's really interesting that it exists contrary to current theories.

NikolaeVarius2• 7 years ago

The article discusses that there are multiple theories explaining the possibility of alternative modes of formation.

joemag2• 7 years ago

Misleading indeed. And I’m surprised the article did not talk about binary black hole mergers being potential sources of such black holes, since that seems like the most plausible theory.

ars• 7 years ago

Did you read the whole article? It did talk about that. It gave a whole explanation.

eesmith• 7 years ago

I thought it did talk about binary black hole merges as one source. Here's a quote from the article which seems to match what you describe:

Inside a globular cluster, a 50-solar-mass black hole could merge with a 30-solar-mass one, for instance, and then the resulting giant could merge again. This second-generation merger is what LIGO/Virgo might have detected

samstave3• 7 years ago

Ok, so now i realize that i have absolutely no idea what a black even actually is.

Can HN ELI5 what a black hole actually is and explain how they even come into existence, let alone that binaries can combine??

SkyBelow2• 7 years ago

Is there an ELICU (college undergrad) as to why 50 to 130 is forbidden but below and above is allowed?

saagarjha4• 7 years ago

How’s the one the article mentions?

A pair-instability supernova happens when the core grows so hot that light begins to spontaneously convert into electron-positron pairs. The light’s radiation pressure had kept the star’s core intact; when the light transforms into matter, the resulting pressure drop causes the core to rapidly shrink and become even hotter, further accelerating pair production and causing a runaway effect. Eventually the core gets so hot that oxygen ignites. This fully reverses the core’s implosion, so that it explodes instead. For cores with a mass between about 65 and 130 times that of our sun (according to current estimates), the star is completely obliterated. Cores between about 50 and 65 solar masses pulsate, shedding mass in a series of explosions until they drop below the range where pair instability occurs. Thus there should be no black holes with masses in the 50-to-130-solar-mass range.

jschwartzi• 7 years ago

Because the black hole can't form from a star of 50 to 130 solar masses but it can, for example, start at 40 solar masses, collapse into a black hole, and then accumulate another 20 solar masses over its lifetime to become a black hole of 60 solar masses.

Edit: the mechanics of this are left as an exercise to the reader.

saiya-jin• 7 years ago

Couldn't it evaporate into this size, or consume enough stars / other material to grow so large? Universe is young, but not so young this should be impossible

semi-extrinsic• 7 years ago

Wrt. evaporation: no. Here is a handy online black hole calculator

http://xaonon.dyndns.org/hawking/

Punch in 130 solar masses, and you get a lifetime (before evaporation) of around 10^72 years. Age of the universe is 10^10 years, so evaporation is utterly negligible.

tgb• 7 years ago

This was my first question, too. Disappointing that HN downvotes good-faith, on-topic questions.

asdfman123• 7 years ago

This is just an observation of a black hole that falls inside the supposedly "forbidden" range.

So you're saying it's of a mass that was thought to be impossible?

endorphone• 7 years ago

If there were prior observed cases, then it certainly wouldn't be thought to be impossible. Instead it's just that theory can't yet explain how.

In the same way that it is, or was, ludicrous when people say it's impossible that bumble bees can fly, when clearly they can. Instead our understanding of their flight mechanics was incomplete.

papreclip• 7 years ago

Maybe he didn't word his post perfectly but he's still pointing out an important distinction. If you could conjure a star of 0.001 solar masses, or one of 1000 solar masses, the first would be a gaseous planet incapable of sustaining a nuclear chain reaction and the second would produce enough energy to overcome the force of gravity at its periphery, blowing away its outer mass and shrinking. Those masses are impossible for stars

A 1000M black hole would be stable, there's just no likely way to end up with one in the first place.

wtdata2• 7 years ago

No, it is of a mass that according to our still standing understanding of astrophysics, is impossible to create by the collapse of "a single star".

But you can very well have this mass by the colapse of two black holes, or by one black hole that ends up consuming one or more stars nearby in due time.

brianberns2• 7 years ago

HN updated their title after I posted my comment. The title of the linked article is still misleading: "Possible Detection of a Black Hole So Big It ‘Should Not Exist’".

sandworm1014• 7 years ago

Also misleading because it is not that the existence of these holes is physically impossible, rather that their formation was extraordinarily unlikely. They can exist along a range of masses, and it is technically possible to make nearly any mass in the range by merging holes. It just very difficult to imaging how such mergers would have happened.

tzs• 7 years ago

For those wondering what the heck you are talking about, it appears that this criticism is of the title of the actual article, which is "Possible Detection of a Black Hole So Big It ‘Should Not Exist’".

I don't know if that was also the HN title at some point, but now the HN title is "Possible detection of a black hole with a mass that was thought to be impossible".

gameswithgo• 7 years ago

on hackernews the top voted comment is always either

* pedantic quibble with title * criticism of style of website on mobile

it makes this kind of a silly place.

Footkerchief• 7 years ago

The accurate headline would be: "So Medium-Sized It Should Not Exist"

luxuryballs• 7 years ago

There’s really no such thing as “should not exist”, only “this challenges our assumptions”. Anything is possible, it might make the human mind uncomfortable but it’s true. Our ability to comprehend and measure things is so unfathomably finite that it’s almost laughable to think we can be sure of anything.

ASalazarMX• 7 years ago

Or, hear me out, "The IMPOSSIBLE black hole that science can't explain".

saalweachter• 7 years ago

"So Medium-Sized It Might Have Been Fairly Uncommon"

rc_kas• 7 years ago

But in 1967, three physicists at the Hebrew University in Jerusalem realized that when the core of a dying star is very heavy, it won’t gravitationally collapse into a black hole. Instead, the star will undergo a “pair-instability supernova,” an explosion that totally annihilates it in a matter of seconds, leaving nothing behind. “The star is completely dispersed into space,” the three physicists wrote.

Does this mean that maybe the big bang was just a unstable pair that did what they describe?

NikolaeVarius2• 7 years ago

The big bang might as well be the almighty space chicken laying an egg for all we care before the moment space-time became a concept worth talking about

jacobush3• 7 years ago

Sometimes referred to as "God". :)

magicalhippo• 7 years ago

Not really.

Lee Smolin has a nice accessible writeup on the Big Bang here[1], what we typically mean by "the Big Bang" and how we seek to replace the Big Bang concept with something better.

[1] https://www.edge.org/response-detail/25371

ben_w• 7 years ago

No. The “pair” in “pair instability collapse supernova” refers to positron-electron pair production.

Specifically, it refers to the situation where the star is hot enough that some of the photons inside it turn into positron-electron pairs which (because conservation laws) move slower than the original photon in the brief time before the positron is annihilated, and therefore contribute less pressure, which causes the start to collapse and get hotter, causing more photons which have the energy to create positron-electron pairs.

The big bang was too big to be a star, at all. If all the matter had been in the same place, it would’ve spontaneously turned directly into a black hole, if not for inflation, which I think is not yet well understood but had effects including causing spacetime to expand by an amount which makes “a lot” seem like “almost nothing” in comparison.

gpderetta• 7 years ago

To further clarify what other have been replaying: the big bang was not an explosion.

cellular• 7 years ago

In all these situations there are forces and other forces that resist original force but under different ranges. It keeps the universe interesting!

Retric4• 7 years ago

Non clickbait headline: ‘Possible detection of Black Hole that grew after formation.’

Honestly, I would have been more intrigued by the less clickbait headline for novelty if nothing else.

Sargos• 7 years ago

Maybe this works from your perspective but for everyone else who doesn't immediately understand that "after formation" is something strange and not normal the title helps people understand that this is an interesting and novel topic and worth exploring more.

pmiller2• 7 years ago

So, stars between 50-130 solar masses don’t directly form black holes because they blow themselves apart at the end of their lives. I got that from the article. Is the idea that a black hole less than 50 solar masses should usually evaporate before it can gain enough mass to fall into that gap?

Edit: or is it just that there shouldn’t be enough around for a smaller black hole to “eat” to become that big?

dsr_• 7 years ago

Sgr A* is thought to be 4+ million solar masses.

GCIRS 13E, 3 ly away from Sag A*, is thought to be 1300 solar masses.

pavel_lishin• 7 years ago

(The million- and billion-solar-mass supermassive black holes that anchor galaxies’ centers formed differently, and rather mysteriously, in the early universe. LIGO and Virgo are not mechanically capable of detecting the collisions of supermassive black holes.)

Is this because those collisions would be too "loud", in the same way that I wouldn't expect my microphone to be able to pick up an earthquake?

ceejayoz• 7 years ago

http://www.astronomy.com/news/2019/07/colliding-supermassive...

If the theories are wrong and there is no problem, supermassive black hole pairs should approach each other and merge frequently enough to create a background “hum” of gravitational waves. “This noise is called the gravitational wave background, and it's a bit like a chaotic chorus of crickets chirping in the night,” Goulding said. “You can't discern one cricket from another, but the volume of the noise helps you estimate how many crickets are out there.” But this hum is outside the hearing range of LIGO and VIRGO, though astronomers are looking forward to projects like LISA, a space-based gravitational wave detector that will “hear” at frequencies current instruments cannot.

jessriedel2• 7 years ago

Supermassive black holes are larger, so the characteristic timescale of their dynamics is longer, and the gravitational waves generated by their merger are correspondingly of lower frequency. More specifically, supermassive black holes binary (SMBHB) mergers usually ring at 0.1-1 millihertz, whereas LIGO's sensitivity is concentrated around more like 0.1-1 kilohertz, a typical frequency of stellar-mass black holes binary mergers. The ~6 orders of magnitude difference comes directly from the fact that supermassive black holes typically weigh in at millions of stellar masses.

See the plot here:

http://www.tapir.caltech.edu/~teviet/Waves/gwave_spectrum.ht...

(To convert from wavelength (meters) to frequency (hertz), take the speed of light and divide it by the wavelength.)

lugg• 7 years ago

So it's like how you can easily see a small swell from a small boat but a larger swell can be almost undetectable.

Is this also why we don't just get ripped apart during one of these ripple events which are probably all around us as gravitational noise?

I wonder if this is why seemingly tiny vessels can cross large oceans just as easily as larger ones.

colechristensen• 7 years ago

I would think it is more like an antenna tuned to a different frequency.

I would expect they would need to be larger to detect the significantly lower frequency.

squarefoot• 7 years ago

I'm a total illiterate in this context, so forgive the possibly stupid question, but the antenna analogy brought this to mind: is there any effect similar to heterodyning with respect to gravitational waves like we have in the electromagnetic ones? If yes, could some signals have been already recorded but elsewhere in the spectrum because they're the result of sum and/or subtraction with other known signals?

tehsauce• 7 years ago

"LIGO and Virgo are not mechanically capable of detecting the collisions of supermassive black holes"

Anyone have ideas why this might be?

skykooler• 7 years ago

The larger black holes have a lower frequency chirp. Supermassive black holes would produce a peak frequency so low it gets filtered out as noise.

ISL• 7 years ago

It isn't filtered out as noise, but rather drowned out by noise.

See Figure 5a: https://arxiv.org/pdf/1604.00439.pdf

dron57• 7 years ago

Because of the lower frequency that would result from the much larger mass collision of the supermassive black holes.

Ideally we would have much longer travel distances for the gravity wave detection experiment. They work by building a giant interferometer with lasers pointed at mirrors that try to estimate how spacetime gets bent by the gravity wave. This should be easier to do with larger distances and less sources of noise in space. LISA is one such project. So hopefully in a couple of decades will know a lot more about supermassive black holes and other huge phenomena after detecting their gravity waves!

wtdata2• 7 years ago

This title is sensationalist.

Of course there are black holes with a lot more than 50 solar masses. It's just that they aren't created in a single event by the death of a star.

https://en.wikipedia.org/wiki/List_of_most_massive_black_hol...

ajuc2• 7 years ago

They can't be created from stars 50-130 solar masses, but they can be still created by joining 2 black holes of smaller masses, right?

The bet seems stupid when you consider black hole in center of Milky Way is supposed to be 4 million times solar mass.

So the prediction was wrong.

phkahler2• 7 years ago

The collisions they're detecting are exactly the kind of events that can create something of the forbidden size. I think the claim is that those objects should not be near another black hole for a subsequent merger?

Accujack• 7 years ago

If you read the article, you'd find out that the supermassive black holes like those at the center of our galaxy were formed very early in the Universe's life, when the laws of physics were different.

Aardwolf• 7 years ago

It's the same laws but at higher energy level.

Depends on how you look at it I guess? Would you say the laws of physics on the moon are different because you can jump higher?

Sharlin• 7 years ago

However, given that the whole point of the LIGO–Virgo experiment is to detect events where black holes merge and result in a single larger black hole, it is seriously weird that the article doesn't acknowledge that fact right away and then proceed to explain why the mass gap still exists.

rsj_hn• 7 years ago

First, this article talks about a mass gap, not a mass ceiling. E.g. stars between 50-130 solar masses shouldn't form black-holes, they should explode. The bet is about finding black holes in this gap.

Second, the issue is LIGOs first 100 detections, not all detections. We know black holes in the mass gap could form by other means such as absorbing other black holes, it was assumed that this type of formation would be rare enough that it would not occur in the first 100 black holes detected by LIGO.

So that was the bet, and the loss of the bet was the occasion to write the article. Unfortunately, while all this information is in the article, several misleading points are also in the article:

* The headline of "a Black Hole So Big It ‘Should Not Exist'" is misleading

* The diagram is equally misleading, not showing a gap but a ceiling

* The mention of this only applying to the first 100 detections is buried at the end of the article, as is the fact that people are well aware that black holes can form via absorption and so enter the gap.

The article makes it look like existing knowledge of black hole formation is being challenged, when what is basically a statistical bet about 100 observations has been settled.

The combination of over simplification and sensationalization is a problem with mediocre science writing, of which this article is unfortunately an example.

01100011• 7 years ago

Can't black holes also inhabit the gap by shrinking via Hawking radiation? Is that something we'd expect to occur given the current age of the universe or does it need longer timescales to occur?

Also, do we know if there were special conditions during the initial phases of the post-big-bang early universe which might change the conditions under which black holes may form? For instance, non-stellar material condensing into a black hole?

_bxg1• 7 years ago

Systems programming is the development and management of software that serves as a platform for other software to be built upon.

What a wonderfully concise definition. I was never sure exactly where to draw the line; "You know, it's, uh, programming where you have to manage memory. They use C for it. It's lower-level, and stuff. It's operating systems but not just operating systems."

cheschire• 7 years ago

Ah, the one Inigo dreamed of.

0xFFFE• 7 years ago

So if I am understanding this correctly, lower threshold (in terms of mass) for a star to become a black hole is lower than what was earlier thought?

Possible detection of a black hole with a mass that was thought to be impossible

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