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Galactic redshift anomalies

  1. Jan 17, 2006 #1
    Hi!

    I just read an article about galactic redshift anomalies discovered by Halton Arp. Do these pose a problem for Big Bang Theory?

    Thanks in advance!
     
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  3. Jan 17, 2006 #2

    Nereid

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    Welcome to Physics Forums, lezardo!

    Halton Arp's 'discoveries' are controversial.

    For example, the principal basis for the 'anomalous' claim is statistical (essentially, 'look, the chances of randomly finding a (dozen) quasar(s) this close to a galaxy are far, far too low'), yet these analyses are full of holes. A secondary basis ('bridges' between the quasar and galaxy) weak (if only because the only redshifts in these 'systems' are those the galaxy and the quasar, nothing in between).

    Further, lensed quasars pretty much knocks out the Arpian idea (at least in the form of 'all quasars are local').

    Finally, the BBT would be alive and well even if a handful of quasars were found to be 'local' (in summary).

    But you said 'galactic redshift anomalies'; perhaps you didn't mean quasars? If so, then it's a new one on me - can you provide a reference please?
     
  4. Jan 17, 2006 #3
    Oops, sorry! No, I meant quasars.
     
  5. Jan 18, 2006 #4

    Chronos

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    Arp's 'theories' have been discredited by so many studies that hardly anyone even blinks when he publishes a new 'paper'. I'm not saying 'crackpot', but, he is often perceived as standing on the shoulders of pottery shards.
     
  6. Jan 18, 2006 #5
    Thanks for your answers. I remember reading 'The Borderlands of Science' by Charles Sheffield in which he also mentioned something about physical connections between galaxies and quasars. He stated that this could possibly pose a problem for BBT. Hadn't this been discredited by the time the book came out (1999, according to Wikpedia)?
    After coming across this problem again (in biblical creationist propaganda being handed out at my university of all places) I just wanted to ask.
     
  7. Jan 19, 2006 #6

    Chronos

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    Arp created a catalog of objects that appeared to have anomalous redshifts - such as 'bridges' between galaxies with discordant redshifts. While not every example has been thoroughly refuted, not a single one has emerged that defies the redshift = distance explanation - which is fundamental to BBT.
     
  8. Jan 23, 2006 #7
    Some astronomers, such as Toomre, have postulated that quasars are the result of galactic collisions. I thought that this explanation of quasars has become relatively well accepted, at least initially. If so, wouldn't these galactic collisions be consistent with Arp's theories that the quasar and adjacent galaxy are physically connected?
     
  9. Jan 24, 2006 #8

    Nereid

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    Except that the quasars seem to be just active galaxy nuclei with normal galaxies around them (the 'quasar host', as it's called) ... at distances from us consistent with their redshifts (i.e. vastly further away than the galaxy Arp claims they've been ejected from). Further, if there were some kind of interaction, how come there's no material - in the bridge - with a redshift in between that of the galaxy and the quasar?

    When you 'do the numbers', you quickly see just how inconsistent with lots of good observations Arp's claims are.
     
  10. Jan 24, 2006 #9

    Chronos

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    Nereid has driven another stake in the heart of this beast. If they truly are bridges, where are the transitional redshifts in the 'bridges'. I usually just whine about 'where are the high redshift objects superimposed in front of low redshift galaxies?'
     
  11. Jan 24, 2006 #10
    I'm not sure if I follow. As you say, quasars are always (as far I know) been found associated with a host galaxy. For the quasars in Alp's atlas, the only nearby (visually) galaxies which could serve as the host galaxies (and which likely are due to the observed dust bridges) are ones with dramatically different redshifts. How does that show Alp to be wrong? Alp and Burbrige even claimed just a year ago to have found a quasar with larger redshift embedded in, or possibly immediately in front of, the galaxy NGC 7319. How could a quasar so far away (if it is far away) be seen clearly through the dust of the central core of a galaxy?
    That assumes what is the scope and nature of the cause of the quasar redshift. Quasars are thought to be rather small, on the order of a singularity up to about the size of our solar system, from what I've read. If the cause of the redshift is a halo of diffuse plasma around the quasar, as postulated by Brynjolfsson, then the light emitting from the compact quasar could be shifted without affecting the light from dust bridges many hundreds or thousands of light years away.
     
  12. Jan 25, 2006 #11

    Nereid

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    The confusion here is 'host'; the host galaxies of quasars (those that have been reliably observed, to date) are very, very close (on the sky) to the photocentre of the quasar ... mostly <2" ... and they surround the photocentre on all sides.

    The 'host galaxies' that you seem to be referring to are those which Arp (and followers) identify as the 'parent' from which the quasar was ejected ... they are almost always >10" away from the nucleus (and in some cases 30' or more), and in only a few cases are the purported 'child' quasars within the 'sky isophotes' of the 'parent'.

    Another curious thing (if you're an Arpian): the sizes and colours of those host galaxies (the real ones, not the Arpian fictions) which have been reliably detected are quite consistent with those of galaxies at the distance that the redshift of the quasar implies (via the Hubble relationship).

    NGC 7319 is an excellent example of the sloppy statistics I referred to above - given the observed sky density of quasars, that of large (on the sky) galaxies, and the well-observed gravitational lensing of background objects that appear near galaxies, an object like the 'quasar within NGC 7319' is entirely unexceptional.

    It's not difficult to find curious alignments - one of my favourites is CG4. The hard part is doing the statistics to show when something curious is more than a chance alignment. As I said earlier, the Arpians have a miserable track record in this regard.
    Indeed. However that would take us beyond the scope of this section of PF - Brynjolfsson's ideas are very clearly non-mainstream (and, I suspect, strongly inconsistent with many many more very good observational and experimental results than Arp's are).
     
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