Material source of the quasar redshift

  • #1

Summary:

When we look at quasar redshift, are we looking at the redshift of the blueshifted jet pointed toward us?
When I see discussions about quasar redshift, exactly what are they talking about? I assume a quasar is similar to a black hole, so emits little radiation from the main mass. The light from a quasar comes principally from its jets of accelerated material, no? Which means the jet pointed toward us is blueshifted and the jet pointed away from us is redshifted, no? And the blueshifted jet would be extra-energized by the blueshift, so would probably obscure the red-shifted jet's spectrum, no? So doesnt all this make determining quasar redshift a complicated affair?

And on a tangentally related note, wouldnt quasar metallicity simply reflect what they are currently devouring, not the primordial blackhole constituent materials? So does that mean metallicity issues concerning quasars, means no galactic cores should have second-generation stars by that time period in the universe? And determining the universe timeframe of the quasar is much dependent on accurately determining its redshift with the issues above?

When I see discussion about quasar redshifts, it appears that the redshift is being used raw without regard to the high degree of falsification owing to the way it is generated. Are all the adjustments handled behind the scenes and taken for granted? If not, then we should assume most quasars are highly blueshifted, which makes their deep redshifts even more puzzling. But as a layman, I assume I am missing the fundamentals of the picture, thus my question. "When we look at quasar redshift, are we looking at the redshift of the blueshifted jet pointed toward us?"
 

Answers and Replies

  • #2
Bandersnatch
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The light from a quasar comes principally from its jets of accelerated material, no?
No, it's principally from the accretion disk. What you seem to be thinking of is not quasars, but blazars - i.e. the relatively rare quasars with their jet beam directed towards Earth.
Which means the jet pointed toward us is blueshifted and the jet pointed away from us is redshifted, no? And the blueshifted jet would be extra-energized by the blueshift, so would probably obscure the red-shifted jet's spectrum, no? So doesnt all this make determining quasar redshift a complicated affair?
Remember that quasars are extended objects, not point sources. One can find the redshift of the host galaxy by blocking the central region of the aperture.

And on a tangentally related note, wouldnt quasar metallicity simply reflect what they are currently devouring, not the primordial blackhole constituent materials?
Yes. One can never know the black hole constituent materials anyway, because black holes have no hair.
But I don't quite get the rest of the question.
 
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  • #3
Hi Bandersnatch, Great name.
Thanks for your answers, and yes I suppose I am talking blazars. I did some reading on related threads below, and found the material jets only move at 1/10 the speed of light, which wont falsify the redshift much. I thought they moved at relativistic speeds, which even then wouldnt much affect readings from high-redshift blazars.
 
  • #4
About metallicity, yes blackholes have no hair, meaning we can never determine what constituents went into it. So all metallicity readings are coming from the accretion disk.
 
  • #5
So you say quasar light comes from the accetion disk being consumed? Hm, that news to me. And that explains their great brightness? Wow, thats gonna take some digesting...
 
  • #6
Thanks again for refining my understanding.
 
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