>When they were born and evolved the first supermassive black holes in the universe?
Astronomers from Tel Aviv University (TAU) identified when there was the cosmic era of the first black holes of rapid growth in the history of the universe.
In general, the galaxies in the universe, including the Milky Way, host supermassive black holes, ranging in mass from one million to 10 billion times the mass of our sun. To find them, astronomers look for huge amounts of radiation emitted for gas during the periods in which the black holes remain "active". Scientists think that is the gas that falls into the supermassive black holes the main responsibility for effective growth.
>The older, faster supermassive black holes grow
The team found that the first black holes, the seed that started the entire growth process when the universe was only 100 million years old, had masses of only 100-1000 times that of the sun. Such black holes may be related to the first stars Universe. The researchers also found that the subsequent era of rapid growth that began after the first 1.2 billion years, lasted only about 100 to 200 million years.
This new study is the culmination of a seven-year project at Tel Aviv University (TAU) designed to monitor the evolution of supermassive black holes and compare them with the evolution of galaxies in which such objects reside.
bump. intetesting topic
>>7746132
Some basic questions to phy/sci/sists:
What are the smallest minimum dimensions of a black hole? Specifically radius and mass. Feel free to give multiple models of these if they exist (Hawking vs. Thorne vs. others)
Is there any sort of maximum on these dimensions, for a black hole?
What's the deal with spinning vs. not-spinning? How can a body not have some "spin" going on?
Has a black hole ever been photographed, or has a real photograph/movie of any region of space illustrated the presence of a black hole?
What are the smallest and largest "known" black holes?
Due to expansion the earlier in the universe a black hole forms, the more matter it can bring into itself and can become larger much more quickly.
>>7746154
so it's just like agar.io kek
>>7746152
1) smallest black holes probably weigh a few Solar masses
2) no physical limit, but in reality black holes attract and heat up a lot of gas and from let's say 20 billion Suns upwards the accretion discs radiation pressure etc. make it hard to attract more stuff
3) every real black hole is probably spinning because practically every star is spinning too, but in theory its possible for black holes to not spin. Its just a simplification of their model.
4) SgA* is probably most interesting one as far as visualisations go because you can easily find gifs of recorded star trajectories orbiting an invisible object
also look up Cygnus X-1 and the event horizon telescope project
otherwise no, no photo where the event horizon itself is visible. Just the EM radiation from the accretion discs. They're just too small and too far away.
5) you can find lists like that on Wiki
>>7747189
>>7746152
>What are the smallest minimum dimensions of a black hole? Specifically radius and mass
>1) smallest black holes probably weigh a few Solar masses
How does that happen? What triggers it initially? I mean there are stars that are 7-10 M and not black holes, yet.
I mean, if they are so massive already wouldn't they collapse already? The outwards forces maintaining them as a supergiant shouldn't be able to even remotely keep them from collapsing into a black hole. Or are those forces so massive that they essentially break the gravity problem that even effects light? Wouldn't light already have trouble escaping and wouldn't everything around them be sucked in already?
I'd think the smallest black hole needs to be at least 100 M
>3) every real black hole is probably spinning because practically every star is spinning too, but in theory its possible for black holes to not spin. Its just a simplification of their model.
They are spinning, but if their immense gravity is fucking up time and slowing down time then from the perspective of an outside observer the blackhole wouldn't ever be spinning.
>otherwise no, no photo where the event horizon itself is visible. Just the EM radiation from the accretion discs. They're just too small and too far away.
This one always stumped me. The "black hole" name shouldn't truly exist in nature because of the very thing you are talking about. It would need to completely run out of incoming materials for it to go totally dark. What chance is it that there are stars we know about now that are actually black holes with tons of material entering them all the time? Yet, we see them as normal stars.
Eh, I guess I'm rambling sci-fi.
>>7747499
I'd answer your questions but if you don't know how black holes form you need to get the basics down and I am not going to spend my time transcribing wikipedia. You can find answers there.
>inb4 wikipedia is shit
>>7747511
I know the basics. It still does not properly explain why it happens. If a mass exists and nothing is added to that mass it will never become a black star or should already be one. A normal star can't become a black star unless something is added. It can't just fizz out and bam black star. Those outward pressures can't be enough to prevent a collapse in the first place. So, something always needs to be added.
>>7747499
I'll give you a upvote becuase you think on the same way as me
>>7746152
>maximum on these dimensions, for a black hole?
max mass seems to be around 50B sun masses, after that the accretion disc becomes too wild and deflects incoming mass
http://www.sciencedaily.com/releases/2015/12/151218085632.htm
>>7747549
to calculate radius for that, use
http://xaonon.dyndns.org/hawking/
Black holes don't increase their gravitational pull from their star counterpart. The supermassive blackholes had to be supersupergiant stars in the past.
>20 billion Suns
Sounds like an episode of 'Terran Cosmology', a timeless game running on some alien screen because a child found it in OrionSector|Fun&Giggles
>>7747700
Kek
>>7747519
wrong
>>7747519
ever heard of radiation pressure f.a.m?
>>7747519
You are confusing mass with density. A black hole is infinitely dense, not massive
>>7746152
In principle, a black hole can have any mass equal to or above the Planck mass (about 22 micrograms). To make a black hole, one must concentrate mass or energy sufficiently that the escape velocity from the region in which it is concentrated exceeds the speed of light. This condition gives the Schwarzschild radius, , where G is the gravitational constant, c is the speed of light, and M the mass of the black hole. On the other hand, the Compton wavelength, , where h is Planck's constant, represents a limit on the minimum size of the region in which a mass M at rest can be localized. For sufficiently small M, the reduced Compton wavelength (, where ħ is Reduced planck constant) exceeds half the Schwarzschild radius, and no black hole description exists. This smallest mass for a black hole is thus approximately the Planck mass.
>>7747499
Rotating black holes are formed in the gravitational collapse of a massive spinning star or from the collapse of a collection of stars or gas with a total non-zero angular momentum. As most stars rotate it is expected that most black holes in nature are rotating black holes. In late 2006, astronomers reported estimates of the spin rates of black holes in the Astrophysical Journal. A black hole in the Milky Way, GRS 1915+105, may rotate 1,150 times per second,[1] approaching the theoretical upper limit.
>>7747499
There are probably plenty of black holes that are not currently ingesting material. The name black hole refers to the fact that it cannot emit anything from past the event horizon where the singularity exists, and hole comes from the idea that info is 'lost' out of the universe through 'a hole in the fabric'.
>>7748852
>A black hole is infinitely dense
Why do physicists get to divide by zero?
And why is the result infinity?
black holes dont exist
>>7748877
Yeah they do, i was in ur mums last nite
>>7748852
Doesn't matter. The area the star takes up prior to it becoming a super dense black hole is actually far inside what that black hole's event horizon is. Thus, all the matter inside that zone is already creating the same amount of gravity and it does when it becomes a black hole. So long as it is withing that zone it does not matter what density the mass is.
>>7748786
Give what I've stated in the above paragraph, the radiation pressure can't keep the matter from becoming a black hole simply because the mass is already so great. The star still needs to have more mass added to it from another source to be able to turn into a black hole.
>>7748877
I to believe this. In fact, this better explains what we see happening than anything else. It is a lot better than saying, "laws of known physic break down inside the event horizon". They can't even prove black holes exist in the first place.
Black holes are the flat earth of Physics and should be treated as science fiction and fringe science.
>>7749411
I don't think you get it. Radiation pressure keeps the mass, even though its huge, "spread out". Thus the mass never compresses below its Schwarzschild radius and black hole doesn't form, even if its a Wolf-Rayet which weighs 250 Suns. When the radiation pressure disappears (fuel for the thermonuclear reaction runs out), there is nothing to stop the matter from compressing. If the mass is large enough, it overcomes each and every obstacle (even electron degeneracy pressure), compresses below its own Schwarzschild radius and becomes a black hole. No mass added. It doesn't matter whether you have 10 Suns or 250 Suns, if you don't compress the matter into small enough volume, you won't get a black hole, period. Radiation pressure of Wolf-Rayets is so big it forces the star to lose mass by the tens of Solar masses, its really powerful.
>The area the star takes up prior to it becoming a super dense black hole is actually far inside what that black hole's event horizon is
What the fuck? This is completely wrong.
>Black holes are the flat earth of Physics and should be treated as science fiction and fringe science.
oh I see, why did I write this, I'll be posting this for someone else to get educated even though this fellow is retarded
>>7749548
>What the fuck? This is completely wrong.
It isn't. Something that massive will have its Schwarzschild radius far beyond its surface. Which is why black holes do not exist.
>>7746132
>from Tel Aviv University
Stopped reading there.
Everyone should boycott all academic work they do until they stop unethically punishing students for not supporting Israel in its numerous atrocities on social media.
>>7749634
Wait, if you don't support Israel you are punished? Most of those academics works are great choices because isn't that expensive, how could you boycott all?
>>7749566
>Which is why black holes do not exist.
What are you talking about?
>>7749634
>we should boycott scientific truth because of the inventors local opinions
As much as I hate religious zealotism, that's just stupid.
>>7749652
>if you don't support Israel you are punished
Students have had their scholarships revoked and been expelled for criticizing Israel's actions. And this shit is not just happening in Israel,
>In February 2014 a bill called the "Protect Academic Freedom Act" was introduced into the U.S. Congress. The legislation "seeks to bar federal funds from going to academic institutions that back the BDS movement." Supporters of the legislation claim that its purpose to oppose "discriminatory boycotts which impede rather than advance the peace process and that seek to deny Israelis the right to free speech on American campuses.” Those opposing the bill claim that it would fiercely violate the First Amendment to the United States Constitution, and many doubt its efficacy as a response to the ASA's boycott movement.[110][111][112]
>In 30 May 2014, Representative Alan Grayson introduced H.R. 4776, a bill "to prohibit an institution of higher education that participates in a boycott of the Israeli government, economy, or academia from receiving funds from the U.S. federal government."
>https://en.wikipedia.org/wiki/Academic_boycotts_of_Israel
>https://theintercept.com/2015/09/25/dianne-feinstein-husband-threaten-univ-calif-demanding-ban-excessive-israel-criticism/
>my wife, your senior Senator, and I talked about this issue at length. She wants to stay out of the conversation publicly but if we do not do the right thing she will engage publicly and is prepared to be critical of this university if we don’t have the kind of not only statement but penalties for those who commit what you can call them crimes, call them whatever you want. Students that do the things that have been cited here today probably ought to have a dismissal or a suspension from school. I don’t know how many of you feel strongly that way but my wife does and so do I.
>http://www.acri.org.il/en/2014/07/28/uni-gaza/
>>7749566
I know you are trolling at this point but for people reading this:
Schwarzschild radius calculation: R=2GM/c^2. This is where the event horizon forms and stays. The only variable in the equation mass, obviously.
For 1 Solar mass its about 3 kilometres. Clearly much much smaller than Sun's radius. This is the radius of a spherical volume into which you'd have to squeeze the Sun for it to become a black hole.
For 260 Solar masses (the mass of R136a1, the most massive known star) the Schwarzschild radius is 768 km. Radius of the star is 21 million kilometres.
If anyone wants to try, you can use this: http://www.wolframalpha.com/widgets/view.jsp?id=15c7a7eb32c8610b005811b8640ebc1
Conclusion: black holes are incredibly tiny compared to the stars they come from.
I use to think i understood black holes until i read this thread.
If a black hole forms and it has the same gravity as the star, how does so much stuff get sucked into it?
And how did the one at the centre of our galaxy manage to get so massive?
-Im guessing it formed at the formation of our galaxy when there was just tons of gass around getting sucked into the centre(but did it even form a star then or just immediately became a black hole?)
>>7749411
>The area the star takes up prior to it becoming a super dense black hole is actually far inside what that black hole's event horizon is
what the fuck? have you studied any of the mathematics behind black holes at all? when the star collapses beyond its schwarzchild radius, it becomes a black hole because past this point the escape velocity is the speed of light (and is therefore insurmountable). if the event horizon exceeds the radius of the star then it's already a black hole.
>>7749841
Damn, /sci/ is as bad as /tv/ when it comes to this fictional non-sense. Flat Earth, science of masturbation, black holes, chemtrails, and on and on. It is like I dropped into a Star Trek thread or something.
Black holes are not real, period.
>>7749793
>And how did the one at the centre of our galaxy manage to get so massive?
Interesting question. what i know about black holes, the fact of the black hole on the center of our galaxy is so massive because i think that galaxies form around giant black holes the way pearls around fragments in the oysters.
According to Robert Massy of the Royal Astronomical Society, although we think of black holes as threatening, in the sense that if you approach one will be in danger, they may have played a role in helping the formation of galaxies not only our own, but all galaxies. They played a role in joining matter and if there is a high matter density enough there are conditions for stars to form. So the first generation of stars and galaxies can be created.
Well.. Undoubtedly the most spectacular aspect of this study of nearly 16 years is that it has delivered what is now considered the best empirical evidence that super-massive black holes really exist.
It's all about the stellar orbits in the galactic center, which show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt.
>>7750028
I'd be interested in your alternative explanation of the incredibly massive, compact and invisible objects we've been observing for decades now.
>>7750426
>i think that galaxies form around giant black holes the way pearls around fragments in the oysters.
No. Galaxy formation in terms of the collapse of dark matter halos has successfully been simulated, with zero black holes. Supermassive black holes are simply tiny in relation to galaxies (far worse at early epochs), they are irrelevant during formation. SMBHs form in galaxies, they do not form galaxies around them.
They may however become important in the evolution of galaxies and how the stellar population and SMBH co-evolve.
>>7749634
u wot meight, im studying physics in TAU and i've never heard anyone punishing anyone for any atrocities or any bullshit like that .
besides what does political bullshit have to do with black holes what you're saying makes no sense .
>>7749659
what the fuck do black holes have to do with religion ?.
>>7749686
it makes no sense that a a university would just boycott countries for no reason .
>>7749686
im not sure how it is in the US but in israel universities are government funded and cannot discriminate anyone or have anything to do with politics .
bump, this shit's interesting.
>>7749659
They are the ones that interfered with academia first. It's also a well known open secret that whenever there is a physics conference in Israel, security will steal data off your laptop and give it to Israeli professors to try and scoop you in your research.
>>7750486
there are some galaxies where their SMBHs take up significant percentage of their total mass (the ones where their BHs have tens of billions Suns), Galaxy is not one of them though
>>7747700
What is this "Terran Cosmology" thing?
