Adopey.128
net.space
utcsrgv!utzoo!decvax!ucbvax!ihnss!mhtsa!rabbit!npois!harpo!chico!duke!unc!dopey.smb
Wed Mar  3 19:56:10 1982
superluminal quasars
Here's the basis for my question about quasars moving faster than light,
from the August 22, 1981 issue of Science News:

	Just a few months ago, only four quasars with components moving
	apart at apparent velocities faster than the speed of light had
	been identified.  Now... there are six.

	... Each of the six has at least one pair of components
	separating at velocities that, from our vantage point, appear to
	be faster than light.  The apparent expansion velocities are all
	in the range of 3 to 10 times the speed of light, with the exact
	numbers depending on which assumed value of the Hubble
	constant... is used.

	... When astronomers refer to "superluminal expansion", they
	don't necessarily mean the components involved actually are
	separating from each other at faster than the speed of light.
	Built into the phrase... is the idea ... "as it appears from
	earth."  The leading explanation... calls on a geometric
	situation in which a relativistic jet from the quasar is moving
	out from the core at a small angle to our line of sight to the
	core.  During any given period since light left the jet on its
	route towards us, the jet itself has moved almost the same
	distance toward us as well.  The light from its second position
	therefore reaches us only a short time after the light from its
	first position.

	... Most astronomers assume this to be what is responsible for
	the measurements of superluminal expansions, although there is
	plenty of uneasiness over the requirement of having the fairly
	special line-of-sight orientation....  Six of twelve, or half,
	the appropriately analyzed quasars have shown it, a troublingly
	high frequency.  However, the twelve are not random samples,
	but highly selective samples, and that might help explain away
	the difficulty.

Now -- does anyone have any later information on this?  (I note in
passing that we seem to have yet another situation where special
alignments are involved, as in the red shift/blue shift discussion.)

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