The Search for celestial positronium via the recombination spectrum

S. C. Ellis, J. Bland-Hawthorn

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Positronium is a short-lived atom consisting of a bound electron-positron pair. In the triplet state, when the spins of both particles are parallel, radiative recombination lines will be emitted prior to annihilation. The existence of celestial positronium is revealed through gamma-ray observations of its annihilation products. These observations, however, have intrinsically low angular resolution. In this paper, we examine the prospects for detecting the positronium recombination spectrum. Such observations have the potential to reveal discrete sources of e + for the first time and will allow the acuity of optical telescopes and instrumentation to be applied to observations of high-energy phenomena. We review the theory of the positronium recombination spectrum and provide formulae to calculate expected line strengths from the e + production rate and for different conditions in the interstellar medium. We estimate the positronium emission line strengths for several classes of Galactic and extragalactic sources. These are compared to current observational limits and to current and future sensitivities of optical and infrared instrumentation. We find that observations of the Psα line should soon be possible due to recent advances in NIR spectroscopy.

LanguageEnglish
Pages457-471
Number of pages15
JournalAstrophysical Journal
Volume707
Issue number1
DOIs
Publication statusPublished - 1 Jan 2009
Externally publishedYes

Fingerprint

positronium
recombination
instrumentation
acuity
spectroscopy
electron-positron pairs
radiative recombination
electron
angular resolution
atomic energy levels
energy
gamma rays
telescopes
estimates
products
atoms

Keywords

  • Elementary particles
  • Line: formation
  • Line: identification

Cite this

Ellis, S. C. ; Bland-Hawthorn, J. / The Search for celestial positronium via the recombination spectrum. In: Astrophysical Journal. 2009 ; Vol. 707, No. 1. pp. 457-471.
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The Search for celestial positronium via the recombination spectrum. / Ellis, S. C.; Bland-Hawthorn, J.

In: Astrophysical Journal, Vol. 707, No. 1, 01.01.2009, p. 457-471.

Research output: Contribution to journalArticleResearchpeer-review

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