Nereid said:Welcome to Physics Forums, lezardo!
Halton Arp's 'discoveries' are controversial.
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?Galoot said: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?
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?Nereid said: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).
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.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?
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.Galoot said: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?Nereid said: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).
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).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.
Galactic redshift refers to the phenomenon where light from distant galaxies appears to be shifted towards the red end of the electromagnetic spectrum. This is due to the expansion of the universe, which causes the wavelengths of light to stretch as it travels through space.
Galactic redshift anomalies are deviations from the expected redshift values observed in galaxies. These can occur due to a variety of factors such as peculiar velocities of galaxies, gravitational lensing, or unknown physical processes.
Galactic redshift can be measured using a technique called spectroscopy, where the light from a galaxy is split into its component wavelengths and the shift towards the red end is measured. This can also be done using the Doppler effect, where the motion of a galaxy away from Earth can be determined by the amount of redshift observed.
Galactic redshift anomalies can provide valuable insights into the structure and evolution of the universe. By studying these anomalies, scientists can better understand the distribution of matter and energy in the universe, as well as the effects of dark matter and dark energy on galactic motion.
Scientists take into account galactic redshift anomalies in their research by using statistical methods to identify and analyze these deviations. They also continue to study and investigate the causes of these anomalies in order to better understand the underlying physical processes at work.