11-November-2004, 04:09 PM
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Order of Kilopi
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Join Date: Dec 2002
Location: Upstate New York
Posts: 4,290
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Quote:
Originally posted by Tim Thompson@Nov 10 2004, 02:00 AM
Well, I can't quite keep up with the furious pace of things around here. So maybe I can just make a few observations of my own.
First, the object in front of NGC 7319 is obviously a microquasar, like I said. The fact that Marti et al. found something else that isn't a microquasar certainly has little to do with our object. There are only 2 distinguishing characteristics of a quasar that seem relevant here, redshift & spectrum. The redshift is a primary indicator of relative velocity, not distance. Anything moving fast will show a large redshift, even if it is next door. So you can't use the redshift as the defining characteristic of a quasar. The spectrum is a better choice, but that will be controversial too. If a cosmological quasar is a black hole surrounded by an accretion disk, it will display the same kind of spectrum as a smaller, closer object, with the same kind of central engine. You can see this in fig 5, the smooth spectrum, in the original paper (I left everything home so I can't remember the citation). In any case, that spectrum shows a very broad Lyman-alpha emission feature, which is doppler broadened by rapid rotation. But the other emission lines are very narrow, which indicates that they are not from the same source as the Lyman-alpha. The narrow lines are likely from a fast moving jet, which explains both the high redshift and the lack of line broadening. In short, there is nothing about this source which requires that it be a cosmological quasar. It has all of the characteristics of a "local" microquasar.
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Tim, what velocity must this object have to give a redshift of z=2.12. And while you insist the Marti et al study has nothing to do with this, they note that a redshift of z=0.11 confirmed the object as a background object and not a microquasar.
And if an object with z=2.12 can be a microquasar in a local galaxy, then why exactly all the resistance to what Arp has been proposing about these associations? Why not just chalk it all up to "velocity" rather than distance?
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"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."
~Timothy Ferris (The Red Limit) 1982
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