Here's a link to their site that has some nice pictures, though!:
( http://www.space.com/php/multimedia/imagegallery/archive.php )
PS: And I was going to refrain from associating hitler clintoon with the title of this article, too! Bad me!. . .
;-)
I get asked all the time: “How do I get on this bump list?” Well the answer is you can’t! The FreeRepublic Master Bump List is not a list of people who get notified about a topic appearing on FreeRepublic but it is a list of topics that you can click on and have posts relevant to those topics displayed to you. There are many topics like “WOD_list” (War On Drugs) or “Homeschool_list” (Stories that Homeschoolers may be interested in) or “Homosexual Agenda” (A list of articles related to that topic). And they all appear on the The FreeRepublic Bump List
When you are reading an article you can add it to the list by posting a reply to that topic and in the “TO” box put the name of the list you want it to appear on preceded by an “*”. For example if you want the article to appear on the War on Drugs list then put “*WOD_list” in the “TO:” box instead of someones screen name. You can also put it on several lists by separating the list names with a simi-colon “;”. Then when you want to see the list go to The FreeRepublic Master Bump List and click on the link for that list.
Here's a hypothesis, which is very likely wrong. As the material falls in towards the black hole, it begins to radiate as it loses gravitational potential energy. We see this as visible light. As it continues, it falls faster and faster, so that it radiates much more intensely. The radiation quickly goes up into the x-ray range. As the material approaches the event horizon, however, gravitational time dilation (i.e., the gravitational redshift) starts to dominate, and the x-ray radiation gets redshifted back down into the visible range.
What's wrong with this is that material doesn't fall straight in to the black hole, but whips around in a tight orbit--the accretion disk--so that the radiation from the infalling matter is successively redshifted or blueshifted by the Doppler effect, depending whether it is travelling away from you or towards you.
What might save my hypothesis is the optical distortion that exists around a black hole. If you look at the accretion disk around a black hole almost edge-on, it doesn't look like the disk of a galaxy. Light takes a curved path around the black hole, so that while the near side of the accretion disk is seen edge-on, the far side of the accretion disk is actually seen face-on! (Look at the simulated black hole image on this page, and you'll get an idea of what it would look like.)
If you look at the accretion disk face-on, of course, there is no Doppler wobble as the material whips around. Since it is possible that the light output could be dominated by the face-on part of the accretion disk, regardless of the orientation of the disk with respect to the observer--thanks to the distortion--my hypothesis might still be correct.
By the way, here's a quick explanation of the idea of "reprocessed" light. All electromagnetic radiation is carried by tiny packets of energy called photons. The energy of each photon is determined by its wavelength; the shorter the wavelength, the higher the energy. When a photon interacts with matter, the typical interaction is to knock an electron from a lower energy state to a higher energy state. After a short time, the electron drops back to its lower energy state, emitting another photon in the process. The energy of the emitted photon corresponds to the change in energy from the higher state to the lower state. Sometimes, the incoming photon can kick an electron up more than one level. Coming back down, the electron can drop in steps, emitting at each step a photon of lower energy than the initial photon. This is what it means to "reprocess" the initial energy down to longer wavelengths.
Almost everyone is familiar with this process even if they don't know what causes it. When you shine "black" (ultraviolet) light on some molecules, the electrons are kicked up several levels, then drop down by steps, emitting photons of visible and infrared light. This is the effect that makes black-light posters work. They were popular in dormitories when I was in college. (Which probably dates me!)
Sounds like my Ex's house...Sorry, I couldn't resist.