Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) was an American

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. He was known for his 1966 ''

Atlas of Peculiar Galaxies 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 ...

'', which (it was later theorized) catalogues many examples of interacting and merging galaxies, though Arp disputed the idea, claiming apparent associations were prime examples of ejections.Halton Arp, ''Seeing Red: Redshift, Cosmology and Academic Science'', Montreal: Aperion (1998), pp. 14, 61–62, 72, 104–105 Arp was also known as a critic of the Big Bang theory and for advocating a

non-standard cosmology A non-standard cosmology is any physical cosmological model of the universe that was, or still is, proposed as an alternative to the then-current standard model of cosmology. The term ''non-standard'' is applied to any theory that does not confo ...

incorporating intrinsic redshift.

Biography

Arp was born on March 21, 1927, in New York City. He was married three times, has four daughters and five grandchildren. His

bachelor's degree A bachelor's degree (from Middle Latin ''baccalaureus'') or baccalaureate (from Modern Latin ''baccalaureatus'') is an undergraduate academic degree awarded by colleges and universities upon completion of a course of study lasting three to six ...

was awarded by Harvard (1949), and his PhD by

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

(1953). Afterward he became a Fellow of the

Carnegie Institution of Washington The Carnegie Institution of Washington (the organization's legal name), known also for public purposes as the Carnegie Institution for Science (CIS), is an organization in the United States established to fund and perform scientific research. Th ...

in 1953, performing research at the

Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observat ...

and Palomar Observatory. Arp became a research assistant at

Indiana University Indiana University (IU) is a system of public universities in the U.S. state of Indiana. Campuses Indiana University has two core campuses, five regional campuses, and two regional centers under the administration of IUPUI. *Indiana Universi ...

in 1955, and then in 1957 became a staff member at Palomar Observatory, where he worked for 29 years. In 1983 he joined the staff of the Max Planck Institute for Astrophysics in Germany. He died in Munich, Germany on December 28, 2013. He was an atheist.

''Atlas of Peculiar Galaxies''

Arp compiled a catalog of unusual galaxies titled ''

'', which was first published in 1966. Arp realized that astronomers understood little about how galaxies change over time, which led him to work on this project. This atlas was intended to provide images that would give astronomers data from which they could study the evolution of galaxies. Arp later used the atlas as evidence in his debate on quasi-stellar objects (QSOs). Other astronomers now recognize Arp's atlas as an excellent compilation of interacting and merging galaxies. Many objects in the atlas are referred to primarily by their Arp number. Many of these objects (particularly Arp 220) are also used as spectral templates for studying high-redshift galaxies. Arp himself disputed the idea that the peculiar galaxies were merging, claiming, rather, that apparent associations were prime examples of ejections from a host galaxy.

Quasars and redshifts

During the 1950s bright radio sources, now known as quasars, had been discovered that did not appear to have an optical counterpart. In 1960 one of these sources,

3C 48 3C48 is a quasar discovered in 1960; it was the second source conclusively identified as such. 3C48 was the first source in the Third Cambridge Catalogue of Radio Sources for which an optical identification was found by Allan Sandage and Thoma ...

, was found to be associated with what appeared to be a small blue star. When the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

of the star was measured, it contained unidentifiable

spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s that defied all attempts at explanation; John Gatenby Bolton's suggestion that these were highly

redshifted In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in f ...

sources was not widely accepted. In 1963

Maarten Schmidt Maarten Schmidt (28 December 1929 – 17 September 2022) was a Dutch-born American astronomer who first measured the distances of quasars. He was the first astronomer to identify a quasar, and so was pictured on the March cover of ''Time'' mag ...

found a visible companion to the quasar

3C 273 3C 273 is a quasar located in the constellation of Virgo. It was the first quasar ever to be identified. It is the optically brightest quasar in the sky from Earth ( m ~12.9), and one of the closest with a redshift, ''z'', of 0.158. A lumino ...

. Using the

Hale telescope The Hale Telescope is a , 3.3 reflecting telescope at the Palomar Observatory in San Diego County, California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation in 1928, he orchestrated the planning, de ...

, Schmidt found the same odd spectra, but was able to demonstrate that it could be explained as the spectrum of hydrogen, shifted by a very large 15.8% If this was due to the physical motion of the "star", it would represent a speed of 47,000 km/s, far beyond the speed of any known star and defying an obvious explanation. Schmidt noted that redshift is also associated with the expansion of the universe, as codified in

Hubble's law Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving a ...

. If the measured redshift was due to expansion, then the object in question would have to be very far away, and therefore have an extraordinarily high luminosity, equally beyond any object seen to date. This extreme luminosity would also explain the large radio signal. Schmidt concluded quasars are very distant, very luminous objects. Schmidt's explanation for the high redshift was not universally accepted at the time. Another explanation that was offered was that it was

gravitational redshift In physics and general relativity, gravitational redshift (known as Einstein shift in older literature) is the phenomenon that electromagnetic waves or photons travelling out of a gravitational well (seem to) lose energy. This loss of energy ...

that was being measured. Several other mechanisms were proposed as well, each with their own problems. In 1966, Arp published the ''Atlas of Peculiar Galaxies'', which contained photographs of 338 nearby galaxies that did not fall into any of the classic categories of galaxy shapes. His goal was to produce a selection that modellers could use in order to test theories of galactic formation. By testing against the collection, one could quickly see how well a particular theory stood up. One group of these, numbers 1 through 101, were otherwise conventional galaxies that appeared to have small companion objects of unknown origin. In 1967 Arp noted that several of these objects appeared on the list of quasars. In some photographs a quasar is in the foreground of known galaxies, and in others there appeared to be matter bridging the two objects, implying they are very close in space. If they are, and the redshifts were due to Hubble expansion, then both objects should have similar redshifts. The galaxies had much smaller redshifts than the quasars. Arp also noted that quasars were not evenly spread over the sky, but tended to be more commonly found in positions of small angular separation from certain galaxies. This being the case, they might be in some way related to the galaxies. Arp argued that the redshift was not due to Hubble expansion or physical movement of the objects, but must have a non-

cosmological Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', and in 1731 taken up in Latin by German philosopher ...

or "

intrinsic In science and engineering, an intrinsic property is a property of a specified subject that exists itself or within the subject. An extrinsic property is not essential or inherent to the subject that is being characterized. For example, mass ...

" origin, and that quasars were local objects ejected from the core of

active galactic nuclei An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...

(AGN). Nearby galaxies with both strong radio emission and peculiar morphologies, particularly M87 and

Centaurus A Centaurus A (also known as NGC 5128 or Caldwell 77) is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable d ...

, appeared to support Arp's hypothesis. Since the 1960s,

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observ ...

s and astronomical instrumentation have advanced greatly: the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...

was launched, and cosmological theory and observation has advanced considerably. Black holes and

supermassive black hole A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical ob ...

s have been directly as well as indirectly detected, extremely distant objects are routinely studied and contextualized, and multiple 8-10 meter

telescopes A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

(such as those at

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when co ...

and the

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m acro ...

) have become operational, and detectors such as CCDs are now more widely employed. These developments, have led to quasars being understood to be very distant active galaxies with high redshifts. Many imaging surveys, most notably the

Hubble Deep Field The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2.6 arcminutes on a side, about one 24-millionth of the ...

, have found many high-redshift objects that are not QSOs but that appear to be normal galaxies like those found nearby. The spectra of the high-redshift galaxies, as seen from

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

to radio wavelengths, match the spectra of nearby galaxies (particularly galaxies with high levels of star formation activity but also galaxies with normal or extinguished star formation activity) when corrected for redshift effects. Arp never wavered from his stand against the Big Bang, and until shortly before his death in 2013, he continued to publish articles stating his contrary view in both popular and scientific literature, frequently collaborating with

Geoffrey Burbidge Geoffrey Ronald Burbidge FRS (24 September 1925 – 26 January 2010) was an English astronomy professor and theoretical astrophysicist, most recently at the University of California, San Diego. He was married to astrophysicist Margaret Burbi ...

(until Burbidge's death in 2010) and

Margaret Burbidge Eleanor Margaret Burbidge, FRS (; 12 August 1919 – 5 April 2020) was a British-American observational astronomer and astrophysicist. In the 1950s, she was one of the founders of stellar nucleosynthesis and was first author of the influentia ...

. He explained his reasons for believing that the Big Bang theory is wrong, citing his research into quasars or quasi-stellar objects (QSOs). Instead, Arp supported the

redshift quantization Redshift quantization, also referred to as redshift periodicity, redshift discretization, preferred redshifts and redshift-magnitude bands, is the hypothesis that the redshifts of cosmologically distant objects (in particular galaxies and quasars) ...

theory as an explanation of the redshifts of galaxies. As more recent experiments have expanded the amount of collected data by orders of magnitude Arp's theories can now be scrutinized further. For instance a recent study by Tang and Zhang about the periodicity of redshifts (a hypothesis articulated by Arp) stated that: :"... the publicly available data from the Sloan Digital Sky Survey and 2dF QSO redshift survey to test the hypothesis that QSOs are ejected from active galaxies with periodic noncosmological redshifts. For two different intrinsic redshift models, ..and find there is no evidence for a periodicity at the predicted frequency in log(1+z), or at any other frequency." However, a follow-up study by Bell and McDiarmid shows that Arp's hypothesis about the periodicity in red-shifts cannot be discarded easily. The authors argue that :"The Tang and Zhang (2005) analysis could thus have missed, or misidentified, many of the parent galaxies, which could explain why the pairs they found differed little from what would be expected for a random distribution. In spite of this, although it was not pointed out by these authors, their pairs did show a slight excess near the expected value of 200 kpc….In fact, most of the conclusions reached by Tang and Zhang (2005) appear to have resulted because they have assumed that many of the values hat they have usedare much more accurate than they really are. … e found by examining 46400 quasars from Sloan Digital Sky Survey thatthe locations of the peaks in the redshift distribution are in agreement with the preferred redshifts predicted by the intrinsic redshift equation"

Honors and awards

In 1960, Arp was awarded the

Helen B. Warner Prize for Astronomy The Helen B. Warner Prize for Astronomy is awarded annually by the American Astronomical Society to a young astronomer (aged less than 36, or within 8 years of the award of their PhD) for a significant contribution to observational or theoretical ...

by the American Astronomical Society, a prize "normally awarded annually for a significant contribution to observational or theoretical astronomy during the five years preceding the award." In the same year, Arp was awarded the

Newcomb Cleveland Prize The Newcomb Cleveland Prize of the American Association for the Advancement of Science (AAAS) is annually awarded to author(s) of outstanding scientific paper published in the Research Articles or Reports sections of ''Science''. Established in 192 ...

for his address, "The Stellar Content of Galaxies", read before a joint session of the American Astronomical Society and AAAS Section D. In 1984, he was awarded the Alexander von Humboldt Senior Scientist Award.Juan Miguel Campanario and Brian Martin,
Challenging dominant physics paradigms
" (2004) ''Journal of Scientific Exploration'', vol. 18, no. 3, Fall 2004, pp. 421–438.

Books

* ''

'' (1966) * ''The Redshift Controversy'' (1973, with

George B. Field George B. Field (born October 25, 1929 in Providence, Rhode Island) is an American astrophysicist. Early life, family and education Field was born in Providence, Rhode Island. His father Winthrop Brooks Field and mother Pauline Woodworth Fie ...

and John N. Bahcall) * '' Quasars, Redshifts and Controversies'' (1987) * ''Seeing Red: Redshifts, Cosmology and Academic Science'' (1998) * ''Catalogue of Discordant Redshift Associations'' (2003)

References

External links

Halton Arp's Website

Oral History interview transcript with Halton Arp on 29 July 1975, American Institute of Physics, Niels Bohr Library and Archives

Publications by Halton C. Arp at the Scientific Commons repository

Halton Arp directory page at the IAU from 2011
{{DEFAULTSORT:Arp, Halton 20th-century American astronomers 21st-century American astronomers 1927 births 2013 deaths American atheists Harvard College alumni California Institute of Technology alumni Indiana University people