PDA

View Full Version : Discussion: Spitzer Sees Hidden Black Holes



Fraser
2005-Aug-04, 05:08 PM
SUMMARY: NASA's Spitzer Space Telescope has peered through walls of galactic dust to spot supermassive black holes called quasars. Some quasars are visible to telescopes, but others are behind so much gas and dust they can only be seen in the infrared spectrum, which is good for viewing through dust. Based on background X-ray radiation, astronomers had an estimate for how many quasars are out there, but they could never see them with telescopes. Now Spitzer has shown that those quasars are there, just hidden.

View full article (http://www.universetoday.com/am/publish/spitzer_finds_hungry_black_holes.html)

What do you think about this story? Post your comments below.

Jsperry20
2005-Aug-04, 05:48 PM
hey, ive only recently got into astonomy and space objects so this might sound a little obvious or silly to some people, but i thought that black holes were so dense that not evan light can escape, so how can they be the brightest objects in the sky if no light can escape, also how come the dust and gas around a quasar doesnt get eaten but the black hole ?

i hope someone can answer my questions, thanks

cran
2005-Aug-04, 11:52 PM
Jsperry20, welcome to UT!

In simplest terms (we won't get into Hawking radiation...yet), you are right - the EMR (electromagnetic radiation - infrared, visible, UV, X-rays, etc) that we can detect is not emerging from the black hole; it is from the torus (annular ring, like a donut) of material surrounding the black hole - the more material there is...the brighter the quasar.

In many early depictions for public consumption, material falling into black holes were shown as dropping straight down; however, if you've watched dirty water draining from a bath, you would have noticed that a vortex forms over the drainhole - the dust and gas around a black hole moves in a similar way.

The energy signals we detect from quasars are from the acceleration and annihilation of matter...before it has fallen beyond the event horizon; if there is no material available, there is virtually no signal to detect from a black hole, and we can only deduce its presence by its gravtitational effect on another (detectable) body (like a star), or if it lies between us and a more distant detectable body (a gravitational lens).

cran
2005-Aug-04, 11:56 PM
I forgot to ask my own question...some sense of scale, please; are the blue (and barely visible red) bits within the same galaxy?

suitti
2005-Aug-05, 02:32 PM
are the blue (and barely visible red) bits within the same galaxy?

I doubt it.

BTW, the triangluar features of some of these bits are an artifact of the Spitzer's optics. It seems to me that they are predictable, and therefore should be correctable with post processing image manipulation. Anyone know of any software that can do this?

Jsperry20
2005-Aug-05, 06:16 PM
Thank you very much cran for the info, very interesting :)

cran
2005-Aug-06, 02:05 AM
Originally posted by Jsperry20@Aug 6 2005, 02:16 AM
Thank you very much cran for the info, very interesting :)
You're welcome, Jsperry20.
I'd feel much more comfortable, for both our sakes, if someone with more expertise clarified the matter. I am, after all, only a rockhound who occasionally looks above the horizon :rolleyes:

Have to say, I don't know, suitti. Your take on the image is that the blues and reds are other galaxies, or intergalactic objects?