Talk:Quasar

How energetic?

"They (...) can emit up to a thousand times the energy output of the Milky Way. (...) The most luminous quasars radiate at a rate that can exceed the output of average galaxies, equivalent to two trillion (2×1012) suns." — Preceding unsigned comment added by 187.4.209.211 (talk) 01:31, 28 May 2012 (UTC)

Lensed quasars

"In 1979 the gravitational lens effect predicted by Einstein's General Theory of Relativity was confirmed observationally for the first time with images of the double quasar 0957+561.[18]" The first confirmation of the gravitational lens effect was by A. Eddington during the 1919 solar eclipse ! M. Tewes (talk) 21:41, 17 September 2012 (UTC)

This is probably referring to the formation of multiple images of the same source object, rather than deflection of light by gravity. I agree that it's a good idea to clarify that in the text. (Einstein also wasn't the first to predict deflection of starlight; the test measured how much it bent, because relativity predicted a different amount of deflection than Newtonian gravity did.) --Christopher Thomas (talk) 00:29, 18 September 2012 (UTC)

Yes, the bending of light by the Sun isn't considered an example of a gravitational lens, even though it's the same effect. The gravitational lens article makes the same distinction. Mhardcastle (talk) 06:35, 18 September 2012 (UTC)

Quasars are "one in a million galaxies", from super-large cDs ?

From figure 4.21 of the following webpage:

http://bigboss.lbl.gov/CH_4.html

the space-density of Quasars, converted to number per volume, peaks near (z~2.3), at nearly 40 per cubic giga-light-year, representing nearly one in a million galaxies. Within 1Gly of earth, there are about a hundred large clusters of galaxies, most presumably harboring large central cD galaxies. Ergo, the spatial density of quasars resembles that of large galaxy clusters, and their large central elliptical galaxies. And, Quasars may be generated, by massive mergers, in busy clusters:

http://www.space.com/8095-mystery-surrounding-brightest-cosmic-objects-solved.html

Inexpertly, a correlation exists, between clusters & cD galaxies, and Quasars, all of which represent approximately one in a million large galaxies. According to Galaxies & Cosmology by Blanchard, Boisse, Combes, & Mazure (pg. 271), observations show an average of 30 Quasars per square degree of sky, implying more than a million potentially-observable Quasars. And, extrapolating to all-sky, from the Hubble Extreme Deep Field, our visible universe harbors hundreds of billions of large galaxies. So Quasars seemingly represent approximately one in a million galaxies. 66.235.38.214 (talk) 12:34, 19 November 2012 (UTC)