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Halton C Arp

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Halton C. Arp
Halton C. Arp
Born(1927-03-21)March 21, 1927
New York City, United States
DiedDecember 28, 2013(2013-12-28) (aged 86)
Munich, Germany
ResidenceD-85741 Garching, Germany
NationalityUSA / German
Known forRedshift, Intrinsic redshift, Quasars, Atlas of Peculiar Galaxies, Big Bang criticism
Scientific career
FieldsAstronomer

Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) was an American astronomer, best known for his 1966 Atlas of Peculiar Galaxies and for his sustained observational challenge to the Big Bang interpretation of redshift. His work on apparently connected objects of widely differing redshift made him one of the most prominent scientific critics of standard cosmology in the twentieth century.

Education

Arp was born on March 21, 1927 in New York City. He received his Bachelor's degree from Harvard College in 1949 and his Ph.D. from the California Institute of Technology in 1953, both cum laude.

Career

After completing his doctorate, Arp became a Fellow of the Carnegie Institution of Washington in 1953, carrying out research at the Mount Wilson and Palomar observatories. He was a Research Assistant at Indiana University from 1955, and joined the staff of Palomar Observatory in 1957, where he remained for close to three decades. Earlier in his career he conducted Edwin Hubble's nova search in M31.

In 1983 Arp moved to Germany to join the staff of the Max Planck Institute for Astrophysics in Garching, where he continued his research until his death in Munich on December 28, 2013.

Atlas of Peculiar Galaxies

While at Palomar, Arp compiled his well-known catalogue of peculiar galaxies — galaxies that are disturbed or irregular in appearance — published in 1966 as the Atlas of Peculiar Galaxies. The catalogue remains widely used; in mainstream astronomy many of its entries were later interpreted as interacting and merging galaxies.

Redshift and the Big Bang

Arp's central and most controversial claim arose from photographs and spectra taken with the large telescopes. He found that many quasars (quasi-stellar objects) with extremely high redshift z values — which on the standard interpretation must be receding rapidly and therefore lie at very great distances — appear to be physically connected to galaxies of low redshift that are known to be relatively nearby.

If such associations are real, then redshift cannot be purely a measure of distance and recession velocity: some component must be intrinsic to the object. On Arp's view this means the assumption that high-redshift objects must be far away — the assumption on which the Big Bang theory and much of accepted cosmology rests — has to be fundamentally re-examined. He developed the argument across four books, including Quasars, Redshifts and Controversies (1987) and Seeing Red (1998), the latter also an account of the professional resistance his work met.

The observational cases

Two pairings became emblematic of the argument. The galaxy NGC 4319 and the quasar-like object Markarian 205 appear, on Arp's reading, to be joined by a bridge of luminous material despite grossly different redshifts. The galaxy NGC 7603 — an entry in his own Atlas of Peculiar Galaxies — has a companion of much higher redshift apparently connected to it by an anomalous luminous arm.

The most striking case came late in his career: in 2005 Galianni, Arp and colleagues reported an X-ray-emitting quasar of redshift z = 2.11 lying within a few arcseconds of the nucleus of the active galaxy NGC 7319 (z = 0.0225), and apparently in front of it. On the standard interpretation the quasar should be some thirty times more distant than the galaxy. He catalogued many further such pairings in his Catalogue of Discordant Redshift Associations (2003).

The ejection model

From this evidence Arp developed a positive account rather than merely a negative one. He proposed that quasars are ejected — often in aligned pairs — from the nuclei of active parent galaxies, beginning life with a large intrinsic redshift that decreases as they age, eventually evolving into ordinary companion galaxies. On this view quasars are not the remote ancestors of galaxies but their nearby offspring.

For a mechanism he drew on the Hoyle–Narlikar variable mass hypothesis, in which newly created matter has low particle mass and correspondingly redshifted spectra, so that a young ejected object appears redshifted because its matter is young rather than because it is receding. Working with Geoffrey Burbidge, he held that quasar redshift disparities reflect this evolutionary process rather than distance. See Intrinsic redshift and Quasar.

Honors

  • Helen B. Warner Prize for Astronomy
  • Newcomb Cleveland Award
  • Alexander von Humboldt Senior Scientist Award
  • Sagnac Award, Natural Philosophy Alliance (2011)

Arp's legacy on this wiki

Arp is the central figure of the redshift and cosmology material catalogued here, and the topic articles built around his work form a connected cluster:

  • Intrinsic redshift — the hypothesis his observations were meant to establish, that part of an object's redshift is intrinsic rather than cosmological.
  • Quasar — the objects at the heart of the dispute, including the discordant associations and the ejection model.
  • Redshift — the wider question of what redshift measures, and the alternative mechanisms proposed for it.
  • Redshift quantization — the independent line of evidence from William G Tifft, which Arp regarded as supporting an intrinsic component; he argued that the correlation function used in mainstream analyses cannot detect quanta that are temporal rather than spatial steps.
  • Hubble's law and Edwin Hubble — the redshift–distance relation Arp's associations call into question, and the fact that Hubble himself never accepted the recession interpretation attached to it.
  • Non-standard cosmology and Big Bang — the broader alternatives and the critical case against the standard model.

His own papers and books are listed below, and further material is indexed under Category:Cosmology and Category:Redshift.

Articles

Abstracts

Books

Media

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