Radiation astronomy/Theory

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This image is the first direct observation of a neutron star in visible light. The neutron star is RX J185635-3754. Credit: Fred Walter (State University of New York at Stony Brook) and NASA.

At its simplest theoretical radiation astronomy is the definition of terms to be applied to astronomical radiation phenomena. In essence, it is the theory of the science of biological, chemical, physical, and logical laws with respect to any natural radiation source in the sky especially at night.

While many of the first terms a student may encounter regarding natural radiation sources in the sky are at a secondary level, the term radiation, perhaps overly associated with the nuclear power, electricity-providing technology and associated mutations (usually fictional), is often reserved for the university undergraduate level and above.

Cautionary speculation is introduced to stimulate the imagination and perhaps open a few doors that may seem closed at present.

This learning resource is in part a lecture and in part an article.

Exploratory theory is the playtime activity that leads to discoveries which better our world. In the radiation physics laboratories here on Earth, the emission, reflection, transmission, absorption, and fluorescence of radiation is studied and laws relative to sources are proven.

The laboratories of radiation astronomy are limited to the radiation observatories themselves. To attempt to understand what is happening outside the observatory, it is necessary to explore the radiation itself within the laboratory. For theoretical radiation astronomy, this laboratory-based science is called astronomical radiation theory. It is the theory of the radiation as tested in the laboratory that explains at least in part the theory needed for radiation astronomy.

Notations[edit | edit source]

To indicate and designate certain relatively specific types of radiation, the Greek alphabet is used. For example, an alpha ray is designated:

Notation: let the Greek lower-case letter α indicate an alpha ray or alpha particle.

Capital Greek letters are often used for baryons.

Notation: let the Greek captial letter Λ indicate a lambda baryon.

English lower-case letters are used for particle forms of radiation which can be described by wave mechanics.

Notation: let the English lower-case letter n denote or indicate a neutron.

English capital letters (upper-case) are used for various types of radiation.

Notation: let the English upper-case (capital) letter X when juxtaposed to -ray indicate radiation at wavelengths longer than those of radiation that emanates from atomic nuclei to those just above the extreme ultraviolet; hence, X-ray, or X-radiation.

Notation: let the capital English letters XUV, or EUV, designate ultraviolet radiation between the far ultraviolet and soft, or ultrasoft, X-rays; specifically extreme ultraviolet.

Notation: let the English upper case letter N indicate a nucleon, or nucleon radiation. In nuclear reactions this letter may also indicate an isotope of the element nitrogen (chemical symbol N).

Notation: let the English upper case letter V indicate violet radiation.

Notation: let the English capital letter B indicate blue radiation.

With respect to subluminal radiation, the term ray (e.g., in cosmic ray) is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles. However, when first discovered, cosmic rays are thought to be rays. Their subatomic particle nature is emphasized by writing cosmic ray particle.

Superluminal radiation does not appear to have any specific designation or notation, but there may be the following:

Notation: let the English capital letters CR indicate Cerenkov radiation.

In the literature when, say, tachyonic gamma rays are discussed, they are referred to as tachyonic γ rays.[1]

Additional notation is indicated when introduced.

Theory[edit | edit source]

The theory of radiation astronomy consists of four fundamental parts:

  1. the derivation of logical laws with respect to radiation,
  2. the definitions of natural radiation sources,
  3. the definition of the sky and associated realms with respect to radiation, and
  4. the discovery, development, and calibration of radiation technology for astronomy.

In addition to the 'universals' of theoretical astronomy which are also applicable to theoretical radiation astronomy, there are specific notations, entities, objects and sources.

Def. the electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when it is deflected by another charged particle, such as an atomic nucleus is called bremsstrahlung.

Def. "the electromagnetic radiation emitted by the accelerating charged particles in a synchrotron that are moving at near the speed of light"[2] is called synchrotron radiation.

Def. light emitted by the Cerenkov effect is called Cerenkov radiation.

Def. any of many mathematical relationships in which something is related to something else by an equation of the form f(x) = a.xk is called a power law.

Def. "ionizing radiation that is naturally present in the environment"[3] is called background radiation.

Hypotheses[edit | edit source]

  1. Observers have been watching the skies and recording what they saw for more than 40,000 years.

See also[edit | edit source]

References[edit | edit source]

  1. Roman Tomaschitz (March 2007). "Superluminal cascade spectra of TeV [gamma-ray sources"]. Annals of Physics 322 (3): 677-700. doi:10.1016/j.aop.2006.11.005. http://wallpaintings.at/geminga/superluminal_cascade_spectra_TeV_gamma-ray_sources.pdf. Retrieved 2011-11-24. 
  2. "synchrotron radiation". San Francisco, California: Wikimedia Foundation, Inc. November 10, 2012. Retrieved 2012-12-21.
  3. "background radiation". San Francisco, California: Wikimedia Foundation, Inc. October 6, 2013. Retrieved 2014-04-10.

Further reading[edit | edit source]

  • James Binney, Michael Merrifield (1998). Galactic Astronomy. Princeton University Press. ISBN 0691004021. OCLC 39108765. 
  • Kaufmann, W. J. (1994). Universe. W H Freeman. ISBN 0-7167-2379-4. 
  • Smith, E.V.P.; Jacobs, K.C.; Zeilik, M.; Gregory, S.A. (1997). Introductory Astronomy and Astrophysics. Thomson Learning. ISBN 0-03-006228-4. 

External links[edit | edit source]

{{Principles of radiation astronomy}}