- Open Access
Astrophysical positronium and Dicke superradiance
Phys. Rev. D 113, 063003 – Published 2 March, 2026
DOI: https://doi.org/10.1103/m7sp-swr1
Abstract
Dicke superradiance is a fascinating phenomenon in which a large number of atoms cooperate to produce a brief and very intense burst of spontaneous emission. This phenomenon has been well studied in the laboratory, but its astrophysical aspects have only recently attracted the attention of a small number of researchers. Since the phenomenon of Dicke superradiance is relatively little known to the wider astrophysical community, we provide a fairly detailed review of its elementary theory in the Appendix and speculate on the significance of superradiance for astrophysical hydrogen and positronium, given the abundant formation of the latter near the Galactic Center.
Physics Subject Headings (PhySH)
Article Text
References (108)
- S. Mohorovičić, Möglichkeit neuer elemente und ihre bedeutung für die astrophysik, Astron. Nachr. 253, 93 (1934).
- D. B. Cassidy, Experimental progress in positronium laser physics, Eur. Phys. J. D 72, 53 (2018).
- M. Randić, Positronium—hydrogen like and unlike, Croat. Chem. Acta 82, 791 (2009), https://hrcak.srce.hr/file/70552.
- H. Kragh, From “electrum” to positronium, J. Chem. Educ. 67, 196 (1990).
- S. C. Ellis and J. Bland-Hawthorn, Astrophysical signatures of leptonium, Eur. Phys. J. D 72, 18 (2018).
- T. Siegert, The positron puzzle, Astrophys. Space Sci. 368, 27 (2023).
- N. Prantzos, C. Boehm, A. M. Bykov, R. Diehl, K. Ferrière, N. Guessoum, P. Jean, J. Knoedlseder, A. Marcowith, I. V. Moskalenko, A. Strong, and G. Weidenspointner, The 511 keV emission from positron annihilation in the galaxy, Rev. Mod. Phys. 83, 1001 (2011).
- I. Mirabel, The great annihilator in the central region of the galaxy, The Messenger 70, 51 (1992), https://www.eso.org/sci/publications/messenger/archive/no.70-dec92/messenger-no70-51-54.pdf.
- M. Leventhal, Galactic positronium, Am. J. Phys. 60, 856 (1992).
- R. H. Dicke, Coherence in spontaneous radiation processes, Phys. Rev. 93, 99 (1954).
- N. Skribanowitz, I. P. Herman, J. C. MacGillivray, and M. S. Feld, Observation of dicke superradiance in optically pumped HF gas, Phys. Rev. Lett. 30, 309 (1973).
- H. Weaver, D. R. W. Williams, N. H. Dieter, and W. T. Lum, Observations of a strong unidentified microwave line and of emission from the OH molecule, Nature (London) 208, 29 (1965).
- F. Rajabi and M. Houde, Dicke’s superradiance in astrophysics. I. The 21 cm line, Astrophys. J. 826, 216 (2016).
- F. Rajabi and M. Houde, Dicke’s superradiance in astrophysics. II. The OH 1612 MHz line, Astrophys. J. 828, 57 (2016).
- F. Rajabi and M. Houde, Explaining recurring maser flares in the ISM through large-scale entangled quantum mechanical states, Sci. Adv. 3, e1601858 (2017).
- M. Houde, A. Mathews, and F. Rajabi, Explaining fast radio bursts through Dicke’s superradiance, Mon. Not. R. Astron. Soc. 475, 514 (2018).
- F. Rajabi, M. Houde, A. Bartkiewicz, M. Olech, M. Szymczak, and P. Wolak, New evidence for Dicke’s superradiance in the 6.7 GHz methanol spectral line in the interstellar medium, Mon. Not. R. Astron. Soc. 484, 1590 (2019).
- M. Houde, F. Rajabi, B. M. Gaensler, A. Mathews, and V. Tranchant, Triggered superradiance and fast radio bursts, Mon. Not. R. Astron. Soc. 482, 5492 (2019).
- F. Rajabi and M. Houde, Astronomical masers and Dicke’s superradiance, Mon. Not. R. Astron. Soc. 494, 5194 (2020).
- M. Houde, F. Rajabi, G. C. MacLeod, S. Goedhart, Y. Tanabe, S. P. van den Heever, C. M. Wyenberg, and Y. Yonekura, Variability, flaring and coherence–the complementarity of the maser and superradiance regimes, Proc. Int. Astron. Union 18, 399 (2022).
- F. Rajabi, M. Houde, G. C. MacLeod, S. Goedhart, Y. Tanabe, S. P. van den Heever, C. M. Wyenberg, and Y. Yonekura, Modelling of the multitransition periodic flaring in G9.62+0.20E, Mon. Not. R. Astron. Soc. 526, 443 (2023).
- T. Rashidi, V. Anari, A. Bartkiewicz, P. Wolak, M. Szymczak, and F. Rajabi, Modelling the periodic 6.7 GHz methanol flaring in G22.356+0.066, Mon. Not. R. Astron. Soc. 542, L12 (2025).
- M. Houde and F. Rajabi, Quantum coherence and the invisible Universe: Subradiance as a dark matter mechanism, arXiv:2412.16663.
- J. H. Eberly, Superradiance revisited, Am. J. Phys. 40, 1374 (1972).
- F. T. Arecchi and E. Courtens, Cooperative phenomena in resonant electromagnetic propagation, Phys. Rev. A 2, 1730 (1970).
- J. C. MacGillivray and M. S. Feld, Theory of superradiance in an extended, optically thick medium, Phys. Rev. A 14, 1169 (1976).
- M. Gross and S. Haroche, Superradiance: An essay on the theory of collective spontaneous emission, Phys. Rep. 93, 301 (1982).
- K. S. Kölbig, Second-order differential equations (Runge–Kutta–Nyström), in CERN Program Library CERNLIB: short writeups (CERN, Geneva, 1996), pp. 119–120.
- M. Benedict, V. Ermolaev, V. Malyshev, I. Sokolov, and E. Trifonov, Super-Radiance. Multiatomic Coherent Emission (Taylor & Francis Group, New York, 1996).
- C. M. Wyenberg, Wideband and relativistic superradiance in astrophysics, Ph.D. thesis, The University of Western Ontario (Canada), 2022.
- E. M. Purcell and G. B. Field, Influence of collisions upon population of hyperfine states in hydrogen, Astrophys. J. 124, 542 (1956).
- W. Mitchell and S. J. Ward, Electron–positronium scattering and photodetachment, J. Phys. B 58, 075203 (2025).
- V. V. Burdyuzha and V. L. Kauts, Positronium in space: Proposal for detection, Astrophys. Space Sci. 258, 329 (1997).
- V. Burdyuzha, P. Durouchoux, and V. Kauts, Space positronium detection by radio measurements, arXiv:astro-ph/9912550.
- I. S. Shklovskii, Possible maser effect in clouds of interstellar hydrogen in the galactic corona, Sov. Astron. 11, 240 (1967), https://adsabs.harvard.edu/full/1967SvA....11..240S.
- R. A. Vlasov, O. N. Gadomskii, and V. V. Samartsev, Annihilation superradiance in a system of positronium atoms and positron polarization of the medium, Theor. Math. Phys. 79, 631 (1989).
- N. Cui, M. Macovei, K. Z. Hatsagortsyan, and C. H. Keitel, Manipulating the annihilation dynamics of positronium via collective radiation, Phys. Rev. Lett. 108, 243401 (2012).
- M. Dijkstra and A. Loeb, Requirements for cosmological 21-cm masers, New Astron. 13, 395 (2008).
- T. Hyodo, T. Nakayama, H. Saito, F. Saito, and K. Wada, The quenching of ortho-positronium, Phys. Status Solidi C 6, 2497 (2009).
- A. Méndez, K. O. Ceballos, and J. I. Zuluaga, Arecibo wow! I: An astrophysical explanation for the wow! Signal, arXiv:2408.08513.
- A. Méndez et al., Arecibo wow! II: Revised properties of the wow! Signal from archival Ohio SETI data, arXiv:2508.10657.
- N. E. Rehler and J. H. Eberly, Superradiance, Phys. Rev. A 3, 1735 (1971).
- L. Men’shikov, The classical model of superradiance and its applications, Phys. Part. Nucl. 29, 392 (1998), https://www.researchgate.net/publication/260503904_The_classical_model_of_superradiance_and_its_applications.
- L. I. Men’shikov, Superradiance and related phenomena, Phys. Usp. 42, 107 (1999).
- L. Landau and E. Lifshitz, The Classical Theory of Fields: Course of Theoretical Physics Vol. 2, 4th ed. (Elsevier, Singapore, 2010).
- S. Bloom, Molecular ringing, J. Appl. Phys. 27, 785 (1956).
- M. D. Crisp, Magnetic effects in radiation reaction theory, Phys. Rev. A 39, 6224 (1989).
- V. Ginzburg, The theory of the excited spin states of elementary particles, J. Exp. Theor. Phys. 13, 33 (1943).
- V. L. Ginzburg, Theoretical Physics and Astrophysics (Elsevier, Amsterdam, 2013).
- F. Rohrlich, Self-energy and stability of the classical electron, Am. J. Phys. 28, 639 (1960).
- J. Schwinger, Electromagnetic mass revisited, Found. Phys. 13, 373 (1983).
- V. V. Zheleznyakov, V. V. Kocharovskiĭ, and V. V. Kocharovskiĭ, Polarization waves and super-radiance in active media, Sov. Phys. Usp. 32, 835 (1989).
- M. Göppert-Mayer, Über elementarakte mit zwei quantensprüngen, Ann. Phys. (Berlin) 401, 273 (1931).
- C. Cohen-Tannoudji, J. Dupont-Roc, and G. Grynberg, Photons and Atoms: Introduction to Quantum Electrodynamics (Wiley, New York, 1989).
- D. A. Steck, Quantum and Atom Optics (University of Oregon, Oregon City, 2007) University of Oregon lecture notes available online: http://atomoptics.uoregon.edu/~tbrown/files/relevant_papers/quantum-optics-notes.pdf.
- W. E. Lamb, Fine structure of the hydrogen atom. III, Phys. Rev. 85, 259 (1952).
- E. A. Power and T. Thirunamachandran, On the nature of the Hamiltonian for the interaction of radiation with atoms and molecules: , , and all that, Am. J. Phys. 46, 370 (1978).
- R. R. Schlicher, W. Becker, J. Bergou, and M. O. Scully, Interaction Hamiltonian in quantum optics or: vs revisited, in Quantum Electrodynamics and Quantum Optics, edited by A. O. Barut (Springer, Boston, 1984), pp. 405–441.
- D. L. Andrews, G. A. Jones, A. Salam, and R. G. Woolley, Perspective: Quantum Hamiltonians for optical interactions, J. Chem. Phys. 148, 040901 (2018).
- N. Funai, J. Louko, and E. Martín-Martínez, vs : Gauge invariance in quantum optics and quantum field theory, Phys. Rev. D 99, 065014 (2019).
- A. Stokes and A. Nazir, Implications of gauge freedom for nonrelativistic quantum electrodynamics, Rev. Mod. Phys. 94, 045003 (2022).
- D. H. Kobe and A. L. Smirl, Gauge invariant formulation of the interaction of electromagnetic radiation and matter, Am. J. Phys. 46, 624 (1978).
- W. E. Lamb, R. R. Schlicher, and M. O. Scully, Matter-field interaction in atomic physics and quantum optics, Phys. Rev. A 36, 2763 (1987).
- V. P. Bykov, Form of the Hamiltonian and the initial conditions in radiation problems, Phys. Usp. 27, 631 (1984).
- P. A. M. Dirac, Gauge-invariant formulation of quantum electrodynamics, Can. J. Phys. 33, 650 (1955).
- P. P. Kulish and L. D. Faddeev, Asymptotic conditions and infrared divergences in quantum electrodynamics, Theor. Math. Phys. 4, 745 (1970).
- C. Gustin, Gauge invariance of the natural lineshape and dissipative dynamics of a two-level system, Phys. Rev. A 112, 053709 (2025).
- E. A. Power and S. Zienau, Coulomb gauge in non-relativistic quantum electro-dynamics and the shape of spectral lines, Phil. Trans. R. Soc. A 251, 427 (1959).
- R. G. Woolley, Molecular quantum electrodynamics, Proc. R. Soc. A 321, 557 (1971).
- M. Babiker, R. Loudon, and G. W. Series, Derivation of the Power-Zienau-Woolley Hamiltonian in quantum electrodynamics by gauge transformation, Proc. R. Soc. A 385, 439 (1983).
- C. Cohen-Tannoudji, B. Diu, and F. Laloë, Quantum Mechanics, Volume 3: Fermions, Bosons, Photons, Correlations, and Entanglement (Wiley-VCH, New York, 2019).
- G. Grynberg, A. Aspect, and C. Fabre, Introduction to Quantum Optics: From the Semi-classical Approach to Quantized Light (Cambridge University Press, Cambridge, England, 2010).
- E. G. Harris, A Pedestrian Approach to Quantum Field Theory (Wiley-Interscience, New York, 1972).
- L. Allen and J. H. Eberly, Optical Resonance and Two-Level Atoms (Dover, New York, 1987).
- V. Kac and P. Cheung, Quantum Calculus (Springer-Verlag, New York, 2002).
- R. P. Feynman, F. L. Vernon Jr., and R. W. Hellwarth, Geometrical representation of the Schrödinger equation for solving maser problems, J. Appl. Phys. 28, 49 (1957).
- C. Fleming, N. I. Cummings, C. Anastopoulos, and B. L. Hu, The rotating-wave approximation: Consistency and applicability from an open quantum system analysis, J. Phys. A 43, 405304 (2010).
- X.-A. Mao and J.-H. Chen, Relation between the delay time and the tipping angle for superradiance, Phys. Rev. A 60, 5140 (1999).
- A. Barone, F. Esposito, C. J. Magee, and A. C. Scott, Theory and applications of the sine-Gordon equation, Riv. Nuovo Cimento 1, 227 (1971).
- D. C. Burnham and R. Y. Chiao, Coherent resonance fluorescence excited by short light pulses, Phys. Rev. 188, 667 (1969).
- Q. H. F. Vrehen and M. F. H. Schuurmans, Direct measurement of the effective initial tipping angle in superfluorescence, Phys. Rev. Lett. 42, 224 (1979).
- M. F. H. Schuurmans and D. Polder, Quantum theory of superfluorescence, in Laser Spectroscopy IV, edited by H. Walther and K. W. Rothe (Springer, Berlin, 1979), pp. 459–470.
- M. Schuurmans, Q. Vrehen, D. Polder, and H. Gibbs, Superfluorescence (Academic Press, New York, 1982), pp. 167–228.
- D. J. Griffiths, Hyperfine splitting in the ground state of hydrogen, Am. J. Phys. 50, 698 (1982).
- C. P. Frahm, Some novel delta-function identities, Am. J. Phys. 51, 826 (1983).
- J. Franklin, Comment on “some novel delta-function identities” by Charles P. Frahm [Am. J. Phys. 51, 826–829 (1983)]; 78, 1225 (2010).
- C. E. Soliverez, The contact hyperfine interaction: An ill-defined problem, J. Phys. C 13, L1017 (1980).
- F. J. Milford, Hyperfine interaction and the knight shift, Am. J. Phys. 28, 521 (1960).
- M. Tinkham, Group Theory and Quantum Mechanics (McGraw-Hill, New York, 1964).
- H. C. Van De Hulst, Origin of the radio waves from space, in Classics in Radio Astronomy (Springer, Dordrecht, 1982), pp. 302–316.
- H. I. Ewen and E. M. Purcell, Observation of a line in the galactic radio spectrum: Radiation from galactic hydrogen at 1,420 Mc./sec., Nature (London) 168, 356 (1951).
- The Cosmic 21-cm Revolution, edited by A. Mesinger (IOP Publishing, Bristol, 2019).
- J. R. Pritchard and A. Loeb, 21 cm cosmology in the 21st century, Rep. Prog. Phys. 75, 086901 (2012).
- H. A. Bethe and E. E. Salpeter, Quantum Mechanics of One- and Two-Electron Atoms (Springer-Verlag, Berlin, 1957).
- N. S. Kardashev, Optimal wavelength region for communication with extraterrestrial intelligence: , Nature (London) 278, 28 (1979).
- P. G. Steffes and D. R. DeBoer, A SETI search of nearby solar-type stars at the 203-GHz positronium hyperfine resonance, Icarus 107, 215 (1994).
- R. Mauersberger, T. L. Wilson, R. T. Rood, T. M. Bania, H. Hein, and A. Linhart, SETI at the spin-flip line frequency of positronium, Astron. Astrophys. 306, 141 (1996), https://articles.adsabs.harvard.edu/pdf/1996A%26A...306..141M.
- L. A. Mason, M. A. Garrett, K. Wandia, and A. P. V. Siemion, Conducting high-frequency radio SETI searches using ALMA, Mon. Not. R. Astron. Soc. 536, 2127 (2024).
- T. Jacq, P. R. Jewell, C. Henkel, C. M. Walmsley, and A. Baudry, in hot dense molecular cloud cores, Astron. Astrophys. 199, L5 (1988), https://articles.adsabs.harvard.edu/pdf/1988A%26A...199L...5J.
- V. B. Berestetskii, E. M. Lifshitz, and L. P. Pitaevskii, Quantum Electrodynamics, Course of Theoretical Physics Vol. 4 (Pergamon Press, Oxford, 1982).
- G. Adkins, D. Cassidy, and J. Pérez-Ríos, Precision spectroscopy of positronium: Testing bound-state QED theory and the search for physics beyond the standard model, Phys. Rep. 975, 1 (2022).
- P. B. Pal, Representation-independent manipulations with Dirac matrices and spinors, arXiv:physics/0703214.
- S. N. Gupta, Particle-particle and particle-antiparticle interactions, Nucl. Phys. 57, 19 (1964).
- A. R. Kuzmak, The physics of the hyperfine structure in the hydrogen atom. The hydrogen line, J. Phys. Stud. 28, 3901 (2024).
- G. E. Stedman, Fermi’s golden rule—an exercise in quantum field theory, Am. J. Phys. 39, 205 (1971).
- T. Yamazaki, A. Miyazaki, T. Suehara, T. Namba, S. Asai, T. Kobayashi, H. Saito, I. Ogawa, T. Idehara, and S. Sabchevski, Direct observation of the hyperfine transition of ground-state positronium, Phys. Rev. Lett. 108, 253401 (2012).
- P. Wallyn, W. A. Mahoney, P. Durouchoux, and C. Chapuis, The positronium radiative combination spectrum: Calculation in the limit of thermal positrons and low densities, Astrophys. J. 465, 473 (1996).
- K. R. Lang, Astrophysical Formulae: A Compendium for the Physicist and Astrophysicist (Springer-Verlag, Berlin, 1980).