Astronomers find an ancient black hole the size of 12B suns | Hacker News Reader

Astronomers find an ancient black hole the size of 12B suns

washingtonpost.com

148 pointsgrej53 comments

To put this result in context, an important open question in astronomy is how supermassive black holes are formed. There are currently two viable formation mechanisms:

1. The bottom-up model: After the first generation of star formation, the most massive stars formed black holes with masses somewhere between 10-100 solar masses. These then began accreting material and merging with each other and gradually grew into the supermassive black holes we see today.

2. The direct collapse model: As galaxies were forming, there was generally a concentration of gas at the bottom of each galaxy's potential well. If this cloud were dense enough, under the right conditions it could collapse directly into a ~10^4-10^6 solar mass black hole without fragmenting into individual stars.

The bottom-up model has historically been considered more plausible because the physics involved is better understood. However, discoveries of very massive black holes very early in the lifetime of the universe are starting to pose very serious challenges for this model. The reason is that black holes cannot grow arbitrarily rapidly. The rate at which a black hole can accrete matter is limited by the "Eddington accretion rate" or the "Eddington limit." Above the Eddington limit the gas gets so hot as it accretes onto the black hole that radiation from the infalling gas blows away the rest of the gas. (There are many details in this process which I have glossed over, but suffice to say it's generally difficult to get an accretion rate that is much more than this limit.)

If you start out with a black hole with a mass of ~100 solar masses and you feed it constantly at the Eddington limit, you can just barely grow black holes large enough to power the quasars we see in the early universe. But as more distant and more massive black holes are discovered, it gets harder and harder to grow a stellar mass black hole into a supermassive black hole in the age that the universe has existed at that time, and you have to invoke mechanisms like super-Eddington accretion and black hole mergers to grow a large enough black hole. This may be possible for individual black holes, but the more fine-tuned the model becomes, the less likely it is to be the primary channel by which supermassive black holes form. These sorts of discoveries are therefore providing evidence that the simple bottom-up picture may not be correct and either super-Eddington accretion, mergers, or direct collapse is necessary to form these black holes.

What could have prevented supermassive black holes to exist from the very start? It would seem quite natural that at the start there were many supermassive black holes with gas around, and so around these holes galaxies formed because of gravitational pull. But if this theory is true, that means there should exist supermassive black holes that don't have their galaxies, or have size mismatches between galaxy and black hole (hole way too big for the size of galaxy). But if they were there from the start and gas distribution were semi even in the universe, then it would be possible that each black hole that popped into existence from the start of big bang got it's own galaxy.

Further what was the time span between initial sequence (Big Bang) and when the Higgs field bound to particles and provided mass?

Suppose there is a discrepancy from the time sub atomic particles gained mass and the initial rate of inflation. If there was, for a mere fraction of a second, a period of super density before inflation kicked, in could that provide a sufficient density of matter to grow massive black holes of this size that subverts the above mentions limit?

> black hole mergers

Black holes can not merge - time dilation means it would take an infinite amount of time for them to do so.

How so? Time dilation doesn't prevent them from moving when observed from a distance.

It would only be infinite for someone in or near the black hole. Not for an observer at a distance.

Relativity

So, as you touch upon, I think mergers are the most likely reason as to the formation of this hole so early.

It didn't start as a single singularity - it started as many, in a matter-dense region of space in the early universe - possibly primordial singularities, or first generation super-massive stellar formed singularities, in a cluster.

If these each then accrete matter from the space surrounding them, they do so independently and each can accrue mass faster than a single singularity of equivalent total mass could while adhering to the Eddington limit. Once the space surrounding them ends up mostly devoid of other matter, the only remaining gravitational influence on them is each other, and thus they start to fall together, coalescing and increasing in mass, changing spin and vector, and potentially causing further coalescence and the availability of fresh matter to consume.

Ultimately, this process would result in a single supermassive singularity which would be exceedingly hot, as it would be massive enough to take in matter from a much larger area than its ancestors, and would do so at a vast rate due to the matter previously being relatively untouched.

Anyway, that's my armchair physicist hypothesis.

> If these each then accrete matter from the space surrounding them, they do so independently and each can accrue mass faster than a single singularity of equivalent total mass could while adhering to the Eddington limit.

The Eddington limit is a linear function of mass, so the accretion onto a collection of objects would not differ from the accretion onto a single object. At least, not because of the Eddington limit – (hydro)dynamics would play a role.

> Ultimately, this process would result in a single supermassive singularity which would be exceedingly hot, as it would be massive enough to take in matter from a much larger area than its ancestors, and would do so at a vast rate due to the matter previously being relatively untouched.

I'm not sure what object you are referring to as "hot". The accretion disks around black holes typically become _cooler_, as the black hole mass increases. And, black holes themselves are aqutally quite cold, as they do not emit significant amounts of radiation.

Things like this make me very skeptical that the accepted model is correct.

Because of its mass, its luminosity, or its age?

Several black holes have already been identified with masses of this magnitude. However, it seems that the age of this black hole is indeed problematic, as indicated by the article:

> For the black hole to grow to such a staggering size in less than a billion years, the astronomers posit, it must have been pulling in interstellar mass from its surroundings at the maximum rate the whole time. Even so, the radiation of the quasar formed by the black hole should have started to limit that mass accumulation before such a size was reached.

> Things like this make me very skeptical that the accepted model is correct.

To which "accepted model" are you referring – the cosmological model for the Universe, the determination of black hole masses, the formation and growth of supermassive black holes, or something else? As @nilkn notes, this discovery is in conflict with existing models of the formation and growth of (some) supermassive black holes, which is a reason this paper is in Nature.

I'll say it. We're running in a virtual machine. There.

...and I get the eery feeling sometimes that it's running Windows 95.

http://en.wikipedia.org/wiki/Holographic_principle

The usefulness of the HP is principally in the application of the aDS/cft duality to otherwise intractable calculations. It doesn't have anything to do with the universe being virtual or computable. Perhaps you are thinking of https://en.wikipedia.org/wiki/Digital_physics.

We already knew about several black holes more massive than that though (the news seems to be about how ancient it is too, not just its mass):

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

Mass, not size. Come on, this is basic astrophysics!

Technically, the radius of a black hole is uniquely determined by its mass, so one can construct a unit system where mass and radius use the same unit of measure...

I want to see that: "How many solar masses is it from Paris to London again?" (115... it's actually a kind of convenient unit, quite close to half an English league and just a bit larger than a Roman league.)

Or: "Man! I stepped on the scales today and I've put on another ten million Planck lengths!"

Randall has us covered, as always.

http://xkcd.com/687/

and

"You can even plug it into Wolfram|Alpha, and it’ll tell you that 20 MPG is about 0.1 square millimeters (roughly the area of two pixels on a computer screen)."

https://what-if.xkcd.com/11/

That unit system might allow comparing black holes to other black holes. But our sun does not have the same density as a black hole, or? The nature article [1] does not compare it to the size of our sun, but to its mass.

[1] http://www.nature.com/nature/journal/v518/n7540/full/nature1...

Actually, black holes density decreases linearly as their mass increases. So, there could easily be a black hole with a density of the sun with supper massive black holes having a density near that of water.

(Where density = mass / volume inside event horizon). Because Gravity ~= Mass/distance ^ 2 but volume is 4/3 pi * r ^ 3

Actually, you can use this unit system (called Geometrized units [1]) for anything, but it is especially convenient for describing black holes and general relativity in general. As a rule of thumb, in the geometrized units, 1 solar mass = ~1.5 km = ~5 microseconds. They have the same units so you can use them interchangeably (Our sun weights 5 microseconds).

I'm just being pedantic here obviously..

[1] http://en.wikipedia.org/wiki/Geometrized_unit_system

Wording nit: entirely determined, not uniquely determined. The former says that mass => size. The latter says that a black hole's mass-size relationship is necessarily unique. Which I don't believe you intended.

Probably stupid question, but do we have solid evidence that the laws of physics/constants were the same/behaved the same back then? I know that to be true for the last couple of billion years. But so early in the development of the universe?

Yes, we have evidence going very far back, for example, the abundances of light elements were set in the first minutes of the big bang, and they have been successfully interpreted with nuclear physics as we know it.

IIRC the laws of nature for this universe were set a few nanoseconds after the big bang. Around the time of inflation.

You can get evidence by observing the early universe with telescopes and the like. I don't think anyone has observed the laws/constants being noticeably different although you can't really prove a negative.

You can put limits on how much they could have changed, though. And people do this, e.g., [0], which found the proton-to-electron mass ratio has not varied by more than a relative factor of 4e-7, over the past 7.5 billion years.

[0] http://arxiv.org/abs/1412.7757

Arxiv paper, with more relevant (albeit highly specialized) information than Nature's abstract:

http://arxiv.org/pdf/1410.2689.pdf

That is not the same paper. The preprint you linked was published in the Astrophysical Journal Letters, and discusses a different quasar (SDSS J013127.34-032100.1, at a redshift of z=2.5). The Nature paper is about SDSS J010013.02+280225.8, at redshift z = 6.30. The author list is similar, so it is likely the same team. But the arxiv link is a different discovery.

I made a typo: the linked paper in the parent comment to mine is about an object at redshift z=5.18, not z=2.5.

Did the big bang and immediate expansion necessarily distribute matter uniformly? If not, couldn't this just be the dumb luck of this black hole that it started its life itself with many solar masses, so it didn't need to accrete as much in the next 900 million years?

The idea is that the incredibly fast inflation immediately following the big bang smeared out the mass and energy of the universe very thinly, so that any unevenness got flattened out.

I love the timing of this with the release of a new/old theory that the universe has always existed :

http://zeenews.india.com/news/space/no-big-bang-new-theory-s...

This would make the age of the this black hole less of a mystery.

I always new that there was a relationship between black holes and quasars (In/Out) but was unaware that there was an established relationship between specific events. Does anyone have links to this ?

I came here to say this. I'm glad you beat me to it!

Cosmology from quantum potential ( Ahmed Farag Ali, Saurya Das )

  It was shown recently that replacing classical geodesics 
  with quantal (Bohmian) trajectories gives rise to a
  quantum corrected Raychaudhuri equation (QRE). In this 
  article we derive the second order Friedmann equations
  from the QRE, and show that this also contains a couple
  of quantum correction terms, the first of which can be
  interpreted as cosmological constant (and gives a correct
  estimate of its observed value), while the second as a
  radiation term in the early universe, which gets rid of
  the big-bang singularity and predicts an infinite age of
  our universe. [1]

[1] http://arxiv.org/pdf/1404.3093v3.pdf

If universe is older than big bang, why don't we see anything older than that? I mean, there isnt such a drop in visibility of galaxy/bright object that is 5 billion vs 10 bilion years old. So, where are all 30 or more billion year old objects? Maybe there wasn't ultimate singularity in the beginning, but universe is definitely not the same no matter how far you look in the past.

I think the answer is here [1].

[1] http://en.wikipedia.org/wiki/Observable_universe#Misconcepti...

The theory you link to would likely not have any bearing on the issue of the existence of this supermassive black hole at such a time. Based on my understanding of it, that new theory predicts that the Universe has always existed, by doing away with the singularity prior to inflation ([0] for some information on inflation). But it does not really affect our understanding of what happens post-inflation. The post-inflation period is when quantum fluctuations are amplified by gravity, resulting in the formation of structure[1].

To be a bit more specific, the relevant time interval for this Nature paper is between when dark matter halos began collapsing and when this quasar turned on, not the interval between the start of the Universe until the quasar turned on. However, in the currently-favored cosmology, the "start" of the Universe is followed very rapidly by the onset of structure formation, so the two are effectively the same point in time (at least, for the purposes of supermassive black hole formation and growth). As it relates to this Nature paper, the theory you reference merely separates the "start" of the Universe from the onset of structure formation, so it doesn't affect the relevant time interval for this particular question.

> I always new that there was a relationship between black holes and quasars (In/Out) but was unaware that there was an established relationship between specific events. Does anyone have links to this ?

It isn't so much a link between specific times as a limit on how quickly you can grow a black hole. The formation of supermassive black holes is fairly uncertain[2], but models generally predict that you start with a black hole that is 1–100 times the mass of the Sun and then grow it by accreting gas. There's a limit to how quickly you can accrete gas[3], so there's a limit to how quickly you can grow the black hole. If you put those two things together, there isn't enough time elapsed between the onset of structure formation and this newly discovered quasar was active, with such a high mass black hole.

[0] https://en.wikipedia.org/wiki/Inflation_%28cosmology%29

[1] https://en.wikipedia.org/wiki/Lambda-CDM_model

[2] https://en.wikipedia.org/wiki/Supermassive_black_hole#Format...

[3] https://en.wikipedia.org/wiki/Eddington_luminosity

Edit: modified wording for clarity.

I wouldn't go so far as to say “no big bang”, at least not exactly. Maybe the phenomenon we interpret as an event at a fixed point in the past is actually happening “all the time” (it's hard to use our language correctly when talking about the thing which defines <time> and <space> in the first place). What if background radiation doesn't actually come “from the past” but is what is left after black holes squirt some of the stuff that fell into them all over space & time in shreds (traversing the singularity)? Just an idea. Anyway, I'm only waiting for the first object to be found that is “older” than the big bang :)

What if it was two supermassive blackholes rotating around center of mass? Could we tell the difference?

Wouldn't time around them be slowed so much that it would look like they don't move at all?

The term to search for would be "supermassive black hole binaries". Apparently, these systems have a characteristic fingerprint.

http://arstechnica.com/science/2015/01/supermassive-black-ho...

How Douglas-Adams funny would it be if the mega black hole had somehow been created by someone spilling their coffee on a keyboard at the CERN LHC

11.

>420 trillion times more luminous than our sun

So that would have a Habitable zone? How far away and how large?

Ignoring all other considerations, one could produce a distance using the inverse square law.

Would that just mean taking the square root of the luminosity and interpreting it as distance in AUs?

So... https://www.google.com/search?q=sqrt%28420*10^12%29au+in+lig...

324 lightyears.

Assuming Sol habitable is 0.7 to 1.2au the translated would be 227 to 389. A shell of thickness approximately 160 light years where everything is in the habitable zone (as long as it is not too close to another heat source)

Can we see it with less than a million bucks (or a trip to Wyoming)?

>It was even detectable with a relatively small telescope, though researchers in China did have to ask for help from astronomers in Chile and the United States to get a higher-resolution look.

I have a feeling that "relatively small" telescopes which find new black holes to publish in Nature are still quite expensive by normal person standards.

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