But were these objects, such as the new and unknown quasars, physically related interacting and close to a galaxy?
Arp compiled the Atlas of Peculiar Galaxies, which is the basic reference work on 338 of the most striking of these objects. As Arp was completing his Atlas in the 1960s, quasars were discovered. These star-like objects have a very high redshift, implying that they are tremendously distant. This would mean that they are unrelated to the closer-in galaxies that Arp was photographing on a regular basis. Even though Arp subscribed to Hubble's Law, he decided to do a study of the newly discovered quasars and see if they are uniformly scattered throughout the sky.
Arp concentrated his analysis on the areas around his beloved peculiar galaxies. By analysing photographs of peculiar galaxies, Arp determined that there are more quasars around the peculiar galaxies than in other sections of the sky. Arp could not measure if the quasars that appeared to be clustering around the peculiar galaxies are actually physically related to peculiar galaxy since he could only measure the distance to galaxies and quasars by Hubble's Law, which puts the quasars much farther away than the peculiar galaxies. But if they are so much farther away, why would there seem to be more of them "hiding" way behind the peculiar galaxies?
If on the other hand, the clustering of quasars near peculiar galaxies really means that the quasars are related to the peculiar galaxies, all bets are off. If the redshift of the quasars really represents velocity, then the quasars are moving away from (if they are behind) or toward it (if they are in front of) the galaxy at 10% to 30% of the speed of light. But since they are all redshifted anywhere they are in the sky, the quasars must all be on the same side of each peculiar galaxy no matter what part of the sky it is in. It is virtually impossible for the quasars to be moving toward (or away from) the galaxies only in the direction of the Earth. Arp was left with the conclusion that the huge redshift of the quasars is not due to velocity but some unknown effect. If this is true for the quasars and they are part of the peculiar galaxies, then Hubble's Law can no longer be relied on for distance determination, and the universe may not be expanding, invalidating the Big Bang theory.
Astronomers have debated Arp's assertion that quasars are related to peculiar galaxies since the late 1960's. Most astronomers believe that quasars are unrelated to the peculiar galaxies...
But no one has been able to explain why the quasars seem to be more numerous around the peculiar galaxies. Arp does not declare that the Big Bang never occurred or that Hubble's Law is wrong. He simply states that he has made an observation that does not fit the accepted theories. Since astronomy (and science in general) is a series of interlocking facts and theories, they cannot be thrown away based on one anomaly.
Preface to Atlas of Peculiar Galaxies, Astrophysical Journal Supplement Number 123, Volume 14, November 1966, University of Chicago Press | Astronomical League
Arp suggested that perhaps these structures had an intrinsic blueshift or redshift that changes. Astronomical object starts with new energy level and this transforms over time. For example when new matter is ejected from quasars they have very little or virtually no mass, the mass of new quasar ejected protons and electrons changes with time, as this matter changes their redshift or blueshift naturally (intrinsic redshift) has to change.
The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp in 1966. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among galaxies...
A large number of the objects have been interpreted as interacting galaxies, including M51 (Arp 85), Arp 220, and the Antennae Galaxies (NGC 4038/NGC 4039, or Arp 244). A few of the galaxies are simply dwarf galaxies that do not have enough mass to produce enough gravity to allow the galaxies to form any cohesive structure. NGC 1569 (Arp 210) is an example of one of the dwarf galaxies in the atlas. A few other galaxies are radio galaxies. These objects contain active galactic nuclei that produce powerful jets of gas called radio jets. The atlas includes the nearby radio galaxies M87 (Arp 152) and Centaurus A (Arp 153).
Many of the peculiar associations present in the catalogue have been interpreted as galaxy mergers, though Arp refuted the idea, claiming, rather, that apparent associations were prime examples of ejections. He writes in Seeing Red:
For me, the whole lesson of the Atlas of Peculiar Galaxies was that galaxies are generally ejected material. The merger mania seems to be a first guess based on a cursory look at galaxies... The Atlas of Peculiar Galaxies contained a very interesting class of galaxies called spirals with companions (smaller galaxies) on the ends of arms. How had they gotten there? Certainly not by accidental collisions or by the beginning of a merger process, which is fashionably used to "explain" everything in the extragalactic realm.
Atlas of Peculiar Galaxies | wikipedia
Centaurus A is one of the first radio sources that revealed “jets and lobes” accelerating out of its nucleus. It was discovered by James Dunlop on August 4, 1826. Dunlop subsequently published, “A Catalogue of Nebulae and Clusters of Stars in the Southern Hemisphere observed in New South Wales” in Philosophical Transactions of the Royal Society, Volume 118, in 1828. Astronomer Halton Arp included Centaurus A in his Atlas of Peculiar Galaxies as Arp 153.
Arp 153 | Thunderbolts
From the 1960s, however, astronomers began to discover strange objects that became known as quasars — intense radio sources whose spectra are shifted dramatically towards longer, redder wavelengths of light, implying they are moving away from our galaxy at enormous velocities and are therefore at extreme distances away from us. Arp began looking at quasars and noticed that many appeared to be lying quite close in the sky to galaxies, sometimes in alignment with them. In 1971 he claimed to have found a “bridge” of gas joining a galaxy named NGC 4319 and a quasar that sits next to it in the sky. As the quasar had a far higher red shift than the galaxy, under conventional Big Bang theory it should be millions or even billions of light years further away. Its apparent proximity needed some explaining.
Most cosmologists concluded that Arp’s observations were wrong, explaining that the galaxy and quasar simply appeared to be close because they were in the same line of sight. Arp’s response was to produce more and more images of objects which seemed to be associated with each other, yet had remarkably different redshifts. One showed a neat row of stellar objects consisting of a deformed spiral galaxy flanked at equal distances by two quasars which appeared to be related to it even though the quasars had enormous red shifts, much bigger than the central galaxy. Another quasar-like object had a redshift which placed it about a billion light years from us, but appeared to be in front of a galaxy only 70 million light years away.
Arp went on to suggest that quasars are created in and ejected by galaxies, and have an “intrinsic” high redshift that has nothing to do with distance or velocity...
While Big Bang is almost universally accepted as the most plausible account of the origin of the universe, it is still only a theory, not proven fact, and in principle should be open to any scientists to test it against alternative cosmological possibilities. Yet Arp found himself being treated as a pariah.
Halton Arp - obituary | The Telegraph
Notwithstanding all the Homeric attempts at galaxy classification, the problem remained that nobody knew what forces shaped normal galaxies, much less peculiar ones. Normal galaxies, at least, displayed recognizable patterns—corkscrews, pinwheels, and spheres—forms that hinted at some underlying, and hopefully apprehensible, dynamic. Peculiars
on the other hand defied description. God only knew what forces shaped them. Moreover, it must be remembered that the Atlas was published at a time when galaxy-galaxy interactions
were considered highly unlikely. Therefore, it was tacitly understood by established researchers that peculiar galaxies were best contained in academic asylum where they could wail and rattle their chains without distracting those outside the walls. This is why Barry Madore couldn’t believe his eyes when he first saw Arp’s Atlas. He was looking upon galactic bedlam.
Arp’s Atlas unlocked the asylum door and threw away the key. But though the “inmates” were now free to rave out in the open, astronomers could still point out that there weren’t
that many of them to matter statistically. They were freaks and they were few. Two developments, however, would change that.
Since Hubble’s day, astronomers have classified galaxies according to their appearance at visual wavelengths—in blue light. But the advent of radio, ultraviolet, and near-infrared observations has shown that a galaxy’s appearance can substantially morph with wavelength. A normal spiral can appear distinctly abnormal depending on whether it is seen in ultraviolet or near-infrared light. Dust as well as its core energy output can also affect a galaxy’s appearance at wavelengths other than those in the visual band...
Taken together, the multiwavelength observations and deep-field findings have significantly altered astrophysicists’ ideas of what a normal galaxy is. In fact, there are no “normal”
galaxies. As Arp presciently wrote in his preface to Atlas of Peculiar Galaxies, when looked at closely enough,every galaxy is peculiar.
The Arp Atlas of Peculiar Galaxies — A Chronicle and Observer’s Guide (preface only and PDF) | Willmann-Bell
Dr. Arp compiled the Atlas with photographs he made mainly using the Palomar 200-inch telescope and the 48-inch Schmidt between 1961 and 1966. The Atlas was published in the Astrophysical Journal Supplement Number 123, Volume 14, November 1966, University of Chicago Press. A small number of larger scale photographic prints of the Atlas were published in 1966 and 1978. Caltech presents an online version of the Atlas, including Arp's original tabular data.
Dr. Arp plays a unique role in the debate on the nature of the universe in general and the galaxies in particular, often standing alone in his assessments of observations on the nature of observed redshifts and the cosmological implications.
Arp's Catalog Of Peculiar Galaxies | Arp Galaxy
Halton suggests when matter is ejected from quasars they have no mass, the mass of new quasar ejected protons and electrons changes with time, as this matter changes their redshift or blueshift naturally (intrinsic redshift) has to change.
A matter of change | Everything Is Electric
Arp Atlas of Peculiar Galaxies, A Chronicle and Observer’s Guide (Preview PDF) | Los Angeles Astronomical Society
Arp Objects in Other Catalogs | Arp Galaxy
Hubble Space Telescope Images of Halton Arps Catalogue Of Peculiar Galaxies | Arp Galaxy