Survey of Super Massive Black Holes Completed 169
eldavojohn writes "NASA has announced the completion of a survey of nearby supermassive black holes. Every galaxy that revolves around a supermassive black hole within 400 light-years of our own galaxy has been cataloged. From the article: 'Called active galactic nuclei, or AGN, these black holes have masses of up to billions of Suns compressed into a region about the size of our solar system. The all-sky census, performed using NASA's Swift satellite over a nine-month period, detected more than 200 nearby AGN.' I'm starting to feel very lucky to have grown up in the Milky Way Galaxy."
relativity (Score:2)
I'm starting to feel very lucky to have grown up in the Milky Way Galaxy.
He might as well be saying he feels lucky that he grew up in Kansas instead of Hawaii.
Is this survey to be trusted? (Score:3, Insightful)
Re:Is this survey to be trusted? (Score:5, Informative)
Because black holes - or, to be precise, the region in space right next to them - emit a lot more radiation. A LOT MORE.
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That sounds suspicious, especially coming from wikipedia. Something with a density that low could not likely bend light enough to keep it from escaping, even if very large.
Density of black holes (Score:5, Informative)
That sounds suspicious, especially coming from wikipedia. Something with a density that low could not likely bend light enough to keep it from escaping, even if very large.
The singularity that bends light does not have that low density. It has an incredibly high density. But the AVERAGE density is the mass of the singularity divided by all that space inside the event horizon.
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Re:Density of black holes (Score:4, Informative)
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So, you've seen this thing in the middle? What's it look like? Enquiring minds want to know!
You are possibly a troll, but it's rather standard to define the size of a black hole by the size of its event horizon. This is largely because we can't actually know anything about what there is behind the event horizon. Maybe there's a singularity there, and maybe there isn't. What we know of physics s
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Ahh. :-) That's actually an interesting distinction. I'm not sure how I can state that in a way that reduces the MEGO factor of the people who read it.
Re:relativity (Score:5, Informative)
It would sound more reasonable coming from Slashdot? What source of information on the Web do you think is more reliable? I've certainly fixed my share of errors on Wikipedia, but that's becuase I hunt them down, as do many others. That kind of fact-checking is almost non-existant on most of the Web, so if I'm going to trust any one source (and I don't) for such information, it would be Wikipedia.
And, as others have noted, you were mis-understanding the definition of "average density". There's a fairly well-known calculation that states that a spherical volume of material with the density of water, and a diameter less than that of Jupiter's orbit would form an event horizon, effectively constituting a black hole. It's a nice visualization of a complex phenomenon. R. Huber has done the math for us [chestnutcafe.com] (pdf) if you want to check for yourself.
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57600 light-seconds
10713600000 miles
The sun is 800,000 miles across. So, width-wise, the solar system is
13392 suns wide
Volume is the cube of the linear width, so the solar system could fit
2,401,797,132,288 sunc
in its volume.
Although the density of the core of the sun is very high, I'm thinking it's not so high that "billions" of suns would make such a volume be denser than water when that volume could hold tw
Re:relativity (Score:4, Informative)
It's nice to see a skeptic; It's a virtue to be a skeptic and not a sin. However, in this case your skepticism is misplaced.
The simplest black hole solution to the equations that govern General Relativity is Schwarzschild's solution. In this he shows that the radius of a black hole is directly proportional to its mass. Elementary geometry tells us that the volume of a sphere is proportional to the cube of the radius. Therefore, the density, which is just mass over volume, that is required to create a blackhole decreases the more mass you have.
I find the figure fairly reasonable for the amount of mass these super-massive black-holes contain.
Simon
400 light years isn't that far... (Score:5, Informative)
It's 400 *million* light years.
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Re:400 light years isn't that far... (Score:4, Informative)
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Well, if you can get a rough estimate of the size of our galaxy, you could judge the distance to the Andromeda galaxy via angular size, assuming they are roughly in the same ballpark of size.
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Also of interest is that proper motion has been measured for m33. No proper motion has yet been detected for m31.
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Re:400 light years isn't that far... (Score:5, Interesting)
http://www.youtube.com/watch?v=mcBV-cXVWFw [youtube.com]
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Have we been able to size our Universe? because if that has happened WTF has happened to all the news about it. "Tonight at 11! The universe gets a size, and
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Really, we only have to measure half of it and multiply 2.
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But here is a handwaving analogy: Imagine two ants on the surface of a balloon. Neither can crawl faster than a, the maximum running speed of an ant[1]. But if somebody is blowing up the balloon, the ants can recede from each other much faster than a.
[1] I dunno, maybe a few mm per second? I'm no ant expert.
...but 78 billion light years is TOO far (Score:3, Informative)
In actual fact the WMAP probe is the furthest we have seen, NOT the Hubble deep field since that looks at the Universe ~300k years after the Big Bang before there were any stars, let alone g
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In summary it seems like saying "This computer I just bought will be over 1,000 years o
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If I understand correctly you can get from
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If I take a photo from the platform of a train pulling out of York station for Kings Cross and show it to someone saying "this is a picture of a train which is 200 miles away" I'd bet the first reaction would be "no it isn't" which would then be followed by "oh you mean now" but only because they know how big a train is. Re
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I'm ignoring it for a good reason - it doesn't make any difference to the photo. Effectively it was taken 10+ billion years ago. There would be no difference between a photo of the galaxy taken 9 billion years ago at a distance 9 billion light years nearer to the galaxy and the one taken today from earth assuming red shift is corrected for. Essentially the photo is a 10+ billion year old pictures of galaxies wh
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What if the small group of cosmologists pushing the "gravity is different at large distances" is correct? Doesn't that change the WMAP predictions to the size of the Universe? (and if so how?) I personally think this unlikely but my understanding is that we can't rule out this possibility yet. So doesn't this put any extrapolations on somewhat questionable ground?
Secondly (just for my interest!) I can understand how the expansion of space will give apparent superluminal
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If you're gonna say that (Score:2)
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I'm starting to feel very lucky... (Score:5, Funny)
Yes. Living near one of those super-massive black holes would certainly suck. Being one with everything around you sounds nice and radiant - but it leaves you all strung out over time, and it seems to take forever! The light at the end of the tunnel is you.
Ryan Fenton
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Because there's a supermassive black hole at the center of our galaxy.
http://en.wikipedia.org/wiki/Sagittarius_A* [wikipedia.org]
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(Parent is right, btw. There's at least one multi-million solar mass black hole within 70K light-years of you. It holds the core of our galaxy together.)
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Our black hole is located near Sagittarius A.
400 light years?!?! (Score:4, Informative)
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SUPERMASSIVEBLACKHOLE (Score:1, Interesting)
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Or goatse
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Damn that one got real big in the last ten years.
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Nope, you aren't. Me and my GF had a laugh when we saw the headline. "Glaciers melting in the dead of night and the superstars sucked into the supermassive..."
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2: I think I need to give these guys a bell as there's a supermassive black hole on my desk right now ^^
We Live in a (semi-)Active Galaxy (Score:3, Informative)
Breaking news from the starship 'Long Shot'... (Score:2)
Hate to break it to you, but, er, that information's actually a little out of date...
Hey, where the hell did all the puppeteers just go?
-- B. Shaeffer
Apparently (Score:1)
Re:Apparently (Score:5, Funny)
Oh great, did you have to bring race *and* religion into this?
Black and holy? That'd be Archbishop Desmond Tutu. (Score:2)
Why is he feeling lucky? (Score:4, Interesting)
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Wait a minute here (Score:2)
Given the size of our galaxy, just how many other galaxies are within 400 lightyears of us, AGN or not? Or am I just massively confused here?
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Thousands, according to this website [galaxieclub.com].
Science for science sake (Score:1)
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You might enjoy this: (Score:2)
Paul B.
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An odd statement given the US government is spending $2 trillion (with a T, not a B or M) per year, a rate that, adjusted for inflation, exceeds per capita any other year in history except for one year during WWII, in which we were engaged in two major war fronts simultaneously and were building a major capital ship per week.
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This isn't science for science's sake. Figuring out how things work is science for science's sake. This is science for scientists that are hunting for something to figure out; it's science for accountancy. I'm not sure that this isn't worse than science for practical applications.
Which do you think kills the imagination faster? Busy-wo
Family Feud? (Score:3, Funny)
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Show me "protoid capsules"!
Wrong (Score:5, Interesting)
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24 years down, 4,999,976 to go!
Re :2 Wrongs don't... (Score:1)
Consider the context of the discussion before satirizing with mean spirit. I'll admit that your rejoinder was humorous--just a cheap shot, imho.
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Would you want a brainstorming session to consist of complete sentences Only?
This isn't a brainstorming session. There is nothing at all to be gained (or lost) based on time to posting, and no reason other than inability or lack of respect for your reader to not structure your post well.
English has
Super Miniature Particles (Score:1)
Survey? (Score:1)
"NASA has announced the completion of a survey of nearby supermassive black holes. Every galaxy that revolves around a supermassive black hole within 400 light-years of our own galaxy has been cataloged.
I'm sure they didn't get every galaxy... You know how things go with censuses; there were probably some galaxies that didn't care about it and claim the form they sent back was lost in the mail or something.
The Milky Way Galaxy (Score:1)
But, today I learned an interesting fact about the milky way bar [wikipedia.org].
Comments from NASA on the survey (Score:2)
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There are no black holes (Score:5, Interesting)
Anyway, as a region of space gets denser, time slows down, and as the density approaches the density required to become black hole, time just freezes.
What you will see when looking at a "black hole" is just a region of space with the eventual event horizon of the hole just frozen in time, and as you move outside, time goes through the "molasses" stage, and as you get further away, gets normal.
The black hole will not form in any finite time since time there just stopped!
For the observer falling towards the "hole", time in the rest of the universe just speeds up. In a matter of minutes the universe will age billions of years, and the observer will first hand know the ultimate fate of the universe in a distant future.
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I expect that if you were close enough to a black hole to experience time outside going by whizzingly fast WITHOUT you being torn apart by gravitational forces it would indeed be quite a show, but just as likely some other object would whiz right into you billions of years hence and your lookout would end.
On Purpose? (Score:3, Insightful)
Because hey, trivia = intelligence, right?
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Yes, I'd expect most of the readership to not realise that in fact. This is a general techy website, not an astro one. Would you expect most people here to know how solar cells work, or how to construct a thermocouple?
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Perhaps not. But I'd expect someone who is consolidating this information to at least do rudimentary fact-checking so as to not spread misinformation.
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Look! A Klemperer Rosette! (Score:1)
hm... (Score:1)
It reminds me of the series finale of Star Trek TNG.
README (Score:2)
Yes, it does make a difference. (-:
That explains things (Score:2)
The catalog (karma whoring) (Score:3, Funny)
The whole catalog:
1. Our own galaxy
Shouldn't That Be 400 MILLION Light Years? (Score:1)
Super Massive Black Hole (Score:1)
Black hole opinions overwhelmingly negative (Score:2)
Blame for Dick Cheney was surprisingly sparse, despite the gravitas he added to Bush's presidential bid in 2000.
Quite possibly the simplest survey ever (Score:2)
They're Not AGN (Score:2)
'Called active galactic nuclei, or AGN, these black holes have masses of up to billions of Suns compressed into a region about the size of our solar system. The all-sky census, performed using NASA's Swift satellite over a nine-month period, detected more than 200 nearby AGN.'
This is wrong. Active Galactic Nuclei are not the same as supermassive black holes. AGN are cases where one of these supermassive black holes is actively accreting on a large scale. The result is an accretion disk which shines brigh
BUt, but, but... (Score:2)
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Maybe the Anthropic Principle wouldn't have it any other way...
In fact, The Anthropic Principle was invented just for such people.