Cosmic background radiation

Short description: Electromagnetic radiation from the Big Bang

Not to be confused with cosmic microwave background or cosmic infrared background.

Part of a series on

Physical cosmology

* Big Bang · Universe
* Age of the universe
* Chronology of the universe

Early universe

* Planck epoch
* Grand unification epoch
* Electroweak epoch
* Quark epoch
* Hadron epoch
* Lepton epoch
* Photon epoch
* Big Bang nucleosynthesis
* Inflation
* Dark Ages

Backgrounds

* Cosmic background radiation (CBR)
* Gravitational wave background (GWB)
* Cosmic microwave background (CMB) · Cosmic neutrino background (CNB)
* Cosmic infrared background (INB)

Expansion · Future

* Hubble's law · Redshift
* Expansion of the universe
* Accelerating expansion of the universe
* Comoving and proper distances
* FLRW metric · Friedmann equations
* Inhomogeneous cosmology
* Future of an expanding universe
* Ultimate fate of the universe
* Heat death of the universe
* Big Rip
* Big Crunch
* Big Bounce

Components · Structure

|  Components

* Lambda-CDM model
* Baryonic matter
* Energy
* Radiation
* Dark energy
* Quintessence
* Phantom energy
* Dark matter
* Cold dark matter
* Warm dark matter
* Hot dark matter
* Dark radiation

Structure

* Shape of the universe
* Reionization · Structure formation
* Galaxy formation
* Large-scale structure
* Large quasar group
* Galaxy filament
* Supercluster
* Galaxy cluster
* Galaxy group
* Local Group
* Galaxy
* Dark matter halo
* Star cluster
* Solar system
* Planetary system
* Void

Experiments

* BOOMERanG
* Cosmic Background Explorer (COBE)
* Dark Energy Survey
* Euclid
* Illustris project
* Large Synoptic Survey Telescope
* Planck space observatory
* Sloan Digital Sky Survey (SDSS)
* 2dF Galaxy Redshift Survey ("2dF")
* UniverseMachine
* Wilkinson Microwave Anisotropy
Probe (WMAP)

* Scientists

* Aaronson
* Alfvén
* Alpher
* Bharadwaj
* Copernicus
* de Sitter
* Dicke
* Eddington
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* Einstein
* Ellis
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* Penzias
* Rubin
* Schmidt
* Schwarzschild
* Smoot
* Starobinsky
* Steinhardt
* Suntzeff
* Sunyaev
* Tolman
* Wilson
* Zeldovich

Subject history

* Discovery of cosmic microwave
background radiation

* History of the Big Bang theory
* Religious interpretations of
the Big Bang theory

* Timeline of cosmological theories

* Category

* v
* t
* e

Temperature of the cosmic background radiation spectrum based on COBE data: uncorrected (top); corrected for the dipole term due to our peculiar velocity (middle); corrected additionally for contributions from our galaxy (bottom).

Cosmic background radiation is electromagnetic radiation that fills all space. The origin of this radiation depends on the region of the spectrum that is observed. One component is the cosmic microwave background. This component is redshifted photons that have freely streamed from an epoch when the Universe became transparent for the first time to radiation. Its discovery and detailed observations of its properties are considered one of the major confirmations of the Big Bang.[1] Background radiation is largely homogeneous and isotropic. A slight detectable anisotropy is present which correlates to galaxy filaments and voids.[2][3] The discovery (by chance in 1965) of the cosmic background radiation suggests that the early universe was dominated by a radiation field, a field of extremely high temperature and pressure.[4]

There is background radiation observed across all wavelength regimes, peaking in microwave, but also notable in infrared and X-ray regimes. Fluctuations in cosmic background radiation across regimes create parameters for the amount of baryonic matter in the universe.[5] See cosmic infrared background and X-ray background. See also cosmic neutrino background and extragalactic background light.

The Sunyaev–Zel'dovich effect shows the phenomena of radiant cosmic background radiation interacting with "electron" clouds distorting the spectrum of the radiation.[6]

## Contents

* 1 Timeline of significant events
* 2 See also
* 3 References
* 4 External links

## Timeline of significant events

1896: Charles Édouard Guillaume estimates the "radiation of the stars" to be 5.6 K.[7]

1926: Sir Arthur Eddington estimates the non-thermal radiation of starlight in the galaxy has an effective temperature of 3.2 K. [1]

1930s: Erich Regener calculates that the non-thermal spectrum of cosmic rays in the galaxy has an effective temperature of 2.8 K.[7]

1931: The term microwave first appears in print: "When trials with wavelengths as low as 18 cm were made known, there was undisguised surprise that the problem of the micro-wave had been solved so soon." Telegraph & Telephone Journal XVII. 179/1"

1938: Walther Nernst re-estimates the cosmic ray temperature as 0.75 K.[7]

1946: The term "microwave" is first used in print in an astronomical context in an article "Microwave Radiation from the Sun and Moon" by Robert Dicke and Robert Beringer.

1946: Robert Dicke predicts a microwave background radiation temperature of 20 K (ref: Helge Kragh)

1946: Robert Dicke predicts a microwave background radiation temperature of "less than 20 K" but later revised to 45 K (ref: Stephen G. Brush).

1946: George Gamow estimates a temperature of 50 K.[7]

1948: Ralph Alpher and Robert Herman re-estimate Gamow's estimate at 5 K.[7]

1949: Ralph Alpher and Robert Herman re-re-estimate Gamow's estimate at 28 K.

1960s: Robert Dicke re-estimates a MBR (microwave background radiation) temperature of 40 K (ref: Helge Kragh).

1965: Arno Penzias and Robert Woodrow Wilson measure the temperature to be approximately 3 K. Robert Dicke, P. J. E. Peebles, P. G. Roll and D. T. Wilkinson interpret this radiation as a signature of the Big Bang.[7]

## See also

* Hot dark matter
* Irradiation
* Unruh effect

## References

1. ↑ Scott, Douglas (2005-10-26), "The standard cosmological model", Canadian Journal of Physics 84 (6–7): 419–435, doi:10.1139/P06-066, arXiv:astro-ph/0510731
2. ↑ Camacho-Ciurana, G.; Lee, P.; Arsenov, N.; Kovács, A.; Szapudi, I.; Csabai, I. (2024-09-01). "The cosmic microwave background lensing imprint of cosmic voids detected in the WISE-Pan-STARRS luminous red galaxy catalog" (in en). Astronomy & Astrophysics 689: A171. doi:10.1051/0004-6361/202348970. ISSN 0004-6361. Bibcode: 2024A&A...689A.171C. https://www.aanda.org/articles/aa/full_html/2024/09/aa48970-23/aa48970-23.html.
3. ↑ Hu, Wayne; Dodelson, Scott (September 2002). "Cosmic Microwave Background Anisotropies" (in en). Annual Review of Astronomy and Astrophysics 40: 171–216. doi:10.1146/annurev.astro.40.060401.093926. ISSN 0066-4146. Bibcode: 2002ARA&A..40..171H.
4. ↑ "First minutes of the Big Bang". What is USA News. 12 March 2014. http://whatisusa.info/the-first-minutes-of-the-big-bang/.
5. ↑ Kashlinsky, A.; Arendt, R. G.; Atrio-Barandela, F.; Cappelluti, N.; Ferrara, A.; Hasinger, G. (2018-06-19). "Looking at cosmic near-infrared background radiation anisotropies". Reviews of Modern Physics 90 (2). doi:10.1103/RevModPhys.90.025006. Bibcode: 2018RvMP...90b5006K. https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.90.025006#s6.
6. ↑ Birkinshaw, Mark (1999-03-01). "The Sunyaev–Zel'dovich effect". Physics Reports 310 (2): 97–195. doi:10.1016/S0370-1573(98)00080-5. ISSN 0370-1573. Bibcode: 1999PhR...310...97B. https://www.sciencedirect.com/science/article/abs/pii/S0370157398000805.
7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Assis, A. K. T.; Neves, M. C. D. (3 July 1995). "History of the 2.7 K Temperature Prior to Penzias and Wilson". Apeiron 2 (3). http://redshift.vif.com/JournalFiles/Pre2001/V02NO3PDF/V02N3ASS.PDF.

## External links

* The Diffuse X-ray and Gamma-ray Background & Deep Fields

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