Hubble directly observes the disc around a black hole | Hacker News Reader

Hubble directly observes the disc around a black hole

physorg.com

116 pointsjaxonrice17 comments

Straight from the European Space Agency, cutting out the physorg blogspam: http://www.spacetelescope.org/news/heic1116/ (press release), http://www.spacetelescope.org/videos/heic1116a/ (video), http://www.spacetelescope.org/static/archives/releases/scien... (paper).

PhysOrg: just say no.

Noted for the next time I submit a space related article. Thanks for the heads up.

The way they're using the gravitational lensing here blows my mind. From what I understand they're using a distant galaxy as a part of the telescope itself to resolve objects behind it. Insane.

Surely this constitues the largest scientific instrument ever?

That's a pretty standard usage of gravitational lensing. It's a giant magnifying glass in space, and they've used them as such since like forever.

Wikipedia describes https://secure.wikimedia.org/wikipedia/en/wiki/Twin_QSO ("Old Faithful") as the first identified gravitationally lensed object.

So, "since forever" is 1979, which makes me feel old.

30+ years ago, so it should, depending on whether you remember 1979. I don't really, I was 5.

In astrophysics, anything more than 15 years old is considered "archeoastronomy."

Makes a change from web programming, where the equivalent period seems to be about four months.

So can anyone tell me why a galaxy is considered to be anything more than a large (and 3-dimensional) black-hole accretion disk?

Galaxy's from huge black holes at their center they don't from around huge black holes that predate them. Also galaxy's have several black holes of various sizes where an accretion disks only includes smaller chunks of matter. They can even have more than one super massive black holes if two older galaxy's collide.

I was going to say "also, galactic stuff never actually falls into the central black hole", but I'm wrong-ish. According to http://en.wikipedia.org/wiki/Future_of_the_universe#Stellar_... it's expected that on a timescale of 10^20 years all the stars (or rather, stellar remnants, since stars will have burned out long before) will either fall into galactic black holes (10%) or get ejected from galaxies entirely (90%).

So, I guess we've got that to look forward to.

Not all of the objects classed as galaxies feature a black hole at the center. Many of the objects classed as galaxies are mere bundles of stars compared to the "traditional" spiral galaxies. Where do galaxies end and globular clusters begin? It is arbitrary.

I'm in danger of veering into category theory/zen buddhism here, so I'll leave it at that.

"directly" is a little bit of an exaggeration

How so?

True, but "directly" is rather relative anyway.

Should it have been "generally relatively"?

Lens Flare

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