Discussion of Arp's paper

Comment Weedman: What is needed to confirm the association of quasars with active galaxies is for you to take a control sample of normal galaxies and demonstrate that quasars are not associated with them.

Answer Arp: That would be very dangerous. "Normal" galaxies undoubtedly have been active in the past and they would be expected to be associated with a slightly older population of second generation objects. Or the galaxy could have quite recently become quiescent. It would be expected that one would find a significant but somewhat weaker association with such galaxies. That would naturally be interpreted as "the association is getting weaker with further measurement". the only correct control is as was done - to compare with similar latitude fields centered on galactic stars. If these results are not believed, then there are no results which would be believed.

Question Gurzadyan: During the recent decade at least two alternative methods have appeared of measuring distances: the gravity lensing and high redshift supernovae. Until now no contradiction with the Hubble Law. So my question is whether you consider the possibility of existence of two different populations of quasars, one at cosmological distances and one ejected from host galaxies? Or do you believe in non-cosmological origin of redshifts of all quasars?

Answer Arp: Extrapolating the numbers of quasars found around Seyferts so far, to the total number of active galaxies in the sky would seem to account roughly for the quasars which are now known. Gravitational lensing you must remember was invented for extragalactic objects because that was the only escape from observations which required the physical association of objects of much different redshifts. The low mass particle masses which characterize matter in younger galaxies will naturally give rise to a lower luminosity. That gives a rough, higher redshift - fainter apparent magnitude, relation for galaxies of different age at the same distance. This should also apply to the supernovae within the galaxies. But the relation is probably not exactly Hubble. In this regard you must face the fact that recent supernova measures around z = 1, show accelerating expansion in a low density universe. Even if you believe "space can expand" it is hard for many astronomers to accept this result.

Question Terzian: In the plots showing galaxies and QSO's, these cover several square degrees. Did you plot all the QSO's in these fields or only the ones of interest.

Answer Arp: In fields like NGC5985 I plotted all catalogued QSO's. In other fields I plotted all objects brighter than a given limit. I know you did not mean to praise the evidence, but I am flattered that you think the plots are so convincing that you should suggest that I had not fairly presented the data.


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