NASA Satellite Sees Black Hole Belching Out Hundred-Million-Degree X-rays 74
The Bad Astronomer writes "NASA's NuSTAR satellite, designed to detect cosmic X-rays, detected a flare of high-energy emission coming from the Milky Way galaxy's central supermassive black hole. The X-rays were the dying gasp of a small gas cloud being torn apart, heated to a hundred million degrees, and then falling into the black hole itself. Events like this are relatively uncommon, so it's fortunate NuSTAR happened to be observing the black hole when it flared."
If you see a black hole (Score:2, Informative)
Isn't it already too late?
Re: (Score:2)
Would it even be possible to see in the first place though.
Not as in detecting that it exists, but photons are only going one way, and that is the same direction you are going.
Re: (Score:1)
Re: (Score:2)
Isn't it already too late?
You'd know it was too late if your spirit was watching your body being irradiated and distorted by the intense magnetic (and other radiation) fields and gravity. You'd be rather amazed while the chap in black, with the scythe rode up on his white horse, Binky and said YOU DON'T SEE THAT EVERY DAY. FIGURATIVELY AND LITERALLY.
Re: (Score:2)
You should look for a precursor, such as glaciers melting in the dead of night.
Re: (Score:1)
Aw, crap. I live on a glacier.
Re: (Score:1)
Burp (Score:5, Funny)
That's taking belching to a very uncivilized level. Someone ought to teach that black hole some table manners.
Re: (Score:3)
Or teach the table how to lighten up and just hold its breath for a moment until it passes.
Obligatory (Score:2)
Oh shit, the infinite improbability drive is on the fritz again.
Re: (Score:2)
Oh shit, the infinite improbability drive is on the fritz again.
Someone just tipped the waiter a penny aboard The Bistromath.
The title makes me weep for science journalism (Score:4, Insightful)
Re:The title makes me weep for science journalism (Score:4, Insightful)
At that temperature the scale is fairly irrelevant. It's less than an order of magnitude difference either way.
Re: (Score:2)
Yep, sure enough: http://science.howstuffworks.com/x-ray2.htm [howstuffworks.com]
Re: (Score:3)
Re: (Score:3, Interesting)
Re: (Score:2)
Re: (Score:2)
Re: (Score:1)
It's a common, but somewhat sloppy, convention in physics to refer a collection of photons whose energies are the same as the Planck distribution for a black-body radiator of temperature T as "T-degree photons".
Whether or not that's reasonable, whether Slashdot titles count as science journalism, whether photons count as matter, and all sorts of other minor points are certainly arguable, but the use of that phrase is hardly the fault of "science journalism".
Re:The title makes me weep for science journalism (Score:5, Informative)
X-Rays have no temperature, they are EM radiation, not matter.
I weep for whoever told you a collection of photons can't have a temperature in the same way a collection of particles can. Who was it? Was it... no one?
Black body radiation has a characteristic temperature just like the black body that produced it, however in the case of the photon gas [wikipedia.org] it's the Plank's Law distribution of energy in photons rather than the Maxwellâ"Boltzmann distribution which describes the matter.
If there's any sloppiness in the title at all it's specifying just the X-rays when you'd technically have to include all photon energies to get the correct temperature, just like you would include all the particles in a gas or solid. However I think it's pretty much in the noise [wolframalpha.com] as far as inaccuracy goes. Unlike your statement. Sorry.
P.S. Such radiation has a temperature and *also entropy*, which is inversely proportional to temperature. So for example if you assume the earth is more or less in equilibrium with the sun, that means the total energy received is equal to the total energy output, but the temperature of the received radiation is much higher, meaning less energy, meaning the earth is emitting a net-positive amount of entropy. In case you've ever wondered how exactly the whole "the earth is not a closed system; it's powered by the sun" thing worked in terms of entropy.
Re: (Score:2)
I weep for whoever told you a collection of photons can't have a temperature in the same way a collection of particles can. Who was it? Was it... no one?
It's pefectly reasonable to think that collections of photons don't have a temperature. It's also perfectly reasonable to think that not everything other than hydrogen and helium is a "metal". Some other posters
Re: (Score:3)
Sure, it's reasonable to think that, just incorrect. Happens all the time. Don't confuse unusual nomenclature with aspects of thermodynamic theory that you weren't familiar with. Don't go complaining about a perfectly correct statement because it doesn't match the high school notion of what temperature means.
Re: (Score:2)
The point I was making is that the definition being used is fairly specialized to the context, just as the definition of "metal" differs from one context to another. Consider how context sensitive mathematical symbols can be. Is it a cross product or a cartesian product or a standard product? Is it a dot product or a logical and? Don't even get me started on the overloading of the greek alphabet. If someone is familiar with a term in one context, confusion is natural when they encounter it in another and it
Re: (Score:2)
The point I was making is that the definition being used is fairly specialized to the context
There is no context in modern science where "only matter can have temperature" is correct.
In short, you can educate someone about the meanings of terms in context without needing to be arrogant jerk about it.
When the someone is sincerely questioning or just confused, then I make every effort not to be. When the someone is themselves being an arrogant jerk, calling a PhD in astronomy stupid because of their own ignorance, I see no reason to be anything else.
If the subject of this thread was "How can X-Rays have temperature?" or similar then you would have seen that reflected in my post.
But it isn't.
Re: (Score:2)
There is no context in modern science where "only matter can have temperature" is correct.
Common definitions of temperature typically define it as a property of matter. Given those kinds of definitions being presented, believing that "only matter can have temperature" is perfectly reasonable. Referring to the temperature of electromagnetic radiation is a convention and not everyone is going to be familiar with this convention.
Remember, not all science is physics. Well, ok, everything actually is ultimately physics, but many other sciences don't focus that way. Medical science, for example, mostl
Re: (Score:2)
Maybe some freshman physics books would gloss over this, but it is an example in just about every introductory thermal physics and statistical mechanics book I've seen.
Okay, but those aren't books that a medical doctor or an archaeologist would need to crack open during the course of their educations. For them, temperature is just a physical property of matter, and the temperature of electromagnetic radiation is an abstract concept.
Re: (Score:2)
X-Rays have no temperature, they are EM radiation, not matter.
I love how people who didn't bother to RTFA get modded insightful. The summary is bad but the article clearly states that the gas creating the X-ray emissions is what is heated.
Re: (Score:2)
If the X-rays have a spectrum that looks at all like a blackbody then temperature is a reasonable way to describe them. If you have a box of material at some temperature, the inside of that box will be filled with electromagnetic radiation who's spectrum matches that temperature and it is reasonable to describe that radiation as having a temperature (even from a technical thermodynamic point if view). As a very rough guide, you get radiation with photon energies in the range of 1eV for 10,000 degrees Kelv
Re: (Score:2)
The energy of a photon at any given frequency is constant. That means that every gamma ray on earth is more energetic than any X-Ray in space. To describe the temperature of a photon is meaningless and gives the false impression that temperature can vary for a given fixed frequency of light. When describing EM Radiation it makes much more sense to consider the energy of the photons in eV or to describe the entire energy amount of a discharge in joules.
The attributing of temperature of light was the aut
Re: (Score:2)
To describe the temperature of a photon is meaningless
To describe the temperature of a massive particle is meaningless.
Only by having a collection of particles (whether massive or not) that follow a particular statistical distribution can temperature be meaningfully talked about. Those distributions are different for different types of collections of particles. The one that describes ideal gasses is not the only one.
and gives the false impression that temperature can vary for a given fixed frequency of light
I suppose if you assume that X-ray is a single fixed frequency and that they were talking about single photons, but that would be as silly as th
Re: (Score:3)
It's clearly a reference to Wien's displacement law [wikipedia.org]. At 100 million kelvins, the peak blackbody emission frequency by the Wien displacement law would be somewhere in the region of 6e18 Hz (0.05 nm), which is well into the hard X ray region, almost energetic enough to be called low-energy gamma rays.
Re: (Score:2)
Hows the view from mount stupid? [smbc-comics.com]
Others have explained the physics, but yes, talking about the temperature of an EM emission is perfectly acceptable, even common, in physics. You could nitpick and say that any particular X-ray photon does not tell you the temperature of what emitted it, but in order to discuss complex matters you need a shorthand, and one of those is to say that a collection of photons has a temperature (whilst really meaning "this collection of photons is consistent with black body emissio
When are we sending astronauts? (Score:2)
Any volunteers?
How does something escape a black hole? (Score:1)
In order to be detected, something must escape a black hole. Since my understanding is that not even photons could escape a black hole, how does these X-Rays manage to do it?
Re: (Score:2)
It was emitted before, not after cloud was absorbed into the black hole...
My favourite lines from TFA:
So maybe saying this was a belch is a bit misleading, since you do that after you eat something. This is more like your food screaming loudly and incoherently and flailing around while you’re actually eating it. Is that better?
Paul B.
Re: (Score:1)
Very good - this will make astrophysics more appealing to cats!
Re: (Score:3)
Hawking radiation escapes.
Re: (Score:2)
Re: (Score:2)
Not only is TFA not talking about Hawking radiation, Hawking radiation doesn't even technically escape. Hawking radiation particles are actually formerly virtual particles that are generated just outside of the event horizon. Virtual particles are created in particle-antiparticle pairs which then instantly self-annihilate before the universe notices. But when the pair appears just outside of a black hole, sometimes one particle falls into the hole allowing the other to continue existing. This produces the i
Re: (Score:2)
It didn't escape the black hole. These photons were generated as matter was falling into the hole and being compressed by the hole's gravity before passing beyond the event horizon. More like they were never inside the hole to begin with.
I hate this (Score:5, Funny)
Naturally. The Bears go to 5 and 1 and look really good to go to the playoffs and here comes a high-energy X-ray cataclysm.
This is how it always goes for me.
Re: (Score:2)
Desperately need some mod points....
Re: (Score:2)
Re: (Score:1)
Hard to bear, eh?
Re: (Score:2)
Cowboys fans on the hand are just happy to have something new to blame on Tony Romo....
Hundred-Million Degrees? (Score:4, Funny)
is that Fahrenheit or Celsius?
Re: (Score:1)
Re: (Score:2)
First one, then the other.
Re: (Score:2)
Only the Lord Kelvin can preserve you from entropy.
A hundred million degrees ain't so much. The University of Mumbai churns out more than that a year.
Upper Limit (Score:2)
Re: (Score:3)
Re: (Score:2)
Your question is equivalent to "Is there a singularity at the beginning of the universe".
Going back through time in conventional cosmology leads you through increasing temperature and density, until conventionally you reach a point where both are infinite - the singularity. This, however, is merely a mathematical result that fits with observations later in the universe, and our theories about gravity. We have no way of directly knowing if the universe ever was a singularity.
too much science-fiction (Score:1)
yap, definitely too much fantasy there
Selection Bias? (Score:1)
Events like this are relatively uncommon, so it's fortunate NuSTAR happened to be observing the black hole when it flared.
And when nobody is looking, nothing happens?
-
-99 pednatic; -999 spilleng; it's the TYPOs