Slashdot Mirror
Astronomers Discovered the Fastest-Growing Black Hole Ever Seen (wral.com)
Long-time Slashdot reader Yhcrana shares "some good old fashioned astronomy news." Astronomers have discovered "a black hole 20 billion times the mass of the sun eating the equivalent of a star every two days," reports the New York Times.
The black hole is growing so rapidly, said Christian Wolf, of the Australian National University, who led the team that found it in the depths of time, "that it is probably 10,000 times brighter than the galaxy it lives in." So bright, that it is dazzling our view and we can't see the galaxy itself. He and his colleagues announced the discovery in a paper to be published in the Publications of the Astronomical Society of Australia...
The blaze from material swirling around this newly observed drainpipe into eternity -- known officially as SMSS J215728.21-360215.1 -- is as luminous as 700 trillion suns, according to Wolf and his collaborators. If it were at the center of our own galaxy, the Milky Way, it would be 10 times brighter than the moon and bathe the Earth in so many X-rays that life would be impossible. Luckily it's not anywhere nearby. It is in fact 12 billion light years away, which means it took that long for its light to reach us, so we are glimpsing this cataclysm as it appeared at the dawn of time, only 2 billion years after the Big Bang, when stars and galaxies were furiously forming.
The blaze from material swirling around this newly observed drainpipe into eternity -- known officially as SMSS J215728.21-360215.1 -- is as luminous as 700 trillion suns, according to Wolf and his collaborators. If it were at the center of our own galaxy, the Milky Way, it would be 10 times brighter than the moon and bathe the Earth in so many X-rays that life would be impossible. Luckily it's not anywhere nearby. It is in fact 12 billion light years away, which means it took that long for its light to reach us, so we are glimpsing this cataclysm as it appeared at the dawn of time, only 2 billion years after the Big Bang, when stars and galaxies were furiously forming.
I assume you know that the black hole itself isn't emitting light, but its accretion disk is. There is a bunch of mass that "falls" into the black hole. This mass doesnt approach it head on, it is traveling by. As the black hole pulls the mass, it speeds up and builds angular momentum. This causes is to form a decaying orbit around the black hole. As it falls, it causes friction with all the rest of the mass falling in at the same time. This generates enormous amounts of heat that glows in various bands of radiation. The most luminous generate X-rays, Gamma-rays, light, infrared rays, microwaves, and lower-frequency radio waves.
This object has a massive accretion disk, that is super-luminous.
It is in fact 12 billion light years away, which means it took that long for its light to reach us,
No, that is not what it means. It took no time for the light at all to reach us. Time passes slower and distances become shorter the faster you go. Travelling at c, the Lorenz factor for the light itself is infinite, and no time passed for it.
What it means is that if light had been governed by Newtonian physics, it would have taken light 12 billion years to get from there to here.
But Newtonian physics turned out to be only an approximation for low speeds, and was overturned a century ago. Einstein discovered that time is a local phenomenon, and that it is meaningless to use phrases like "ago" for relativistic speeds and distances - no two clocks will ever agree, and may disagree by billions of years.
Whenever I see news like that, it reminds me that we're not really "seeing" anything. We just get tons of astronomic data, basically piles of photons and neutrinos and muons and god knows what, with different frequencies and spins and all that. Then we take that data, and start working towards mapping it all onto our continuously evolving and obviously imperfect theory what all that actually means. So astronomers in the end decide what the data means, and then you have these sensationalist articles in the media about "the things we see". Over time, theories will change, data will prove to be imperfect or contain some margin of error previously unaccounted for, etc, etc. So articles like this are quite meaningless. There is real data with real impact on the theory, but it's also very likely that data like that will over the long term change the theory and our understanding of the universe, with the sensationalist concepts of "giant black hole eating up whole galaxy" simply dying the way of the dodo. Good job astronomers for expanding the human knowledge! But let's take the sensationalist sentences with a grain of doubt.....
Sounds like the cookie monster of the cosmos. By the time a lot of the light from the stars reaches us, the star could already be dead or consumed. Astronomy never fascinated me all of that much but the sheer size of the universe is simply awe-inspiring. The light that we see from these distant stars could be coming from dead ones and we would never really know it. That, in of itself, astounds me.
So it's eating a star every two days, with an accretion disk managing the luminosity of 700 trillion suns.
If you take the Sun's current output and hold that constant for 4.6 billion years and then emit that total energy over two days, you get 0.1% of 700 trillion Sol brightnesses.
The mass balance here must be way strange, involving some kind of seriously supersized all-you-can-eat hot stardust buffet.
> Travelling at c, the Lorenz factor for the light itself is infinite
No, it's not travelling at C, "for it".
Also did you mean Lorentz factor? More importantly, did you forget the "relative" in "relativity"?
If you look at it from the light's reference frame, it didn't move, and there's nothing to talk about. It's moving at C only from *our* reference frame. Therefore the only reference frame that's useful to discuss, the reference from from which something happened, is ours. The frame in which it took 12 billion years for the light to reach us.
12 billion years old.