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Dipole radiation and kinetic mixing from dark photon solitons

Enrico D. Schiappacasse1,* and Moira Venegas2

  • *Contact author: enrico.schiappacasse@uss.cl
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Phys. Rev. D 113, 123537 – Published 22 June, 2026

DOI: https://doi.org/10.1103/mhkg-qr6r

Abstract

Wavelike dark matter composed of spin-1 particles, known as dark photons, is theorized to form clumps called “vector solitons.” These solitons are compact astrophysical objects that exhibit coherent oscillations and a high concentration relative to the local dark matter density. A significant portion of dark matter in galactic halos today may consist of these solitons. This study explores how photons can be produced from these vector solitons by the influence of external electromagnetic fields or charge densities, via a dimension-6 dark photon-photon coupling and a kinetic mixing, respectively. We further explore the astrophysical implications of these phenomena, highlighting a novel avenue for dark matter discovery that our research provides.

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References (118)

  1. G. Bertone and D. Hooper, History of dark matter, Rev. Mod. Phys. 90, 045002 (2018).
  2. K. Freese, Status of dark matter in the universe, Int. J. Mod. Phys. D 1, 325 (2017).
  3. M. Cirelli, A. Strumia, and J. Zupan, Dark matter, arXiv:2406.01705.
  4. T. D. Brandt, Constraints on MACHO dark matter from compact stellar systems in ultra-faint dwarf galaxies, Astrophys. J. Lett. 824, L31 (2016).
  5. N. Dalal and A. Kravtsov, Excluding fuzzy dark matter with sizes and stellar kinematics of ultrafaint dwarf galaxies, Phys. Rev. D 106, 063517 (2022).
  6. M. A. Amin and M. Mirbabayi, A lower bound on dark matter mass, Phys. Rev. Lett. 132, 221004 (2024).
  7. R. Essig et al., Working group report: New light weakly coupled Particles, in Snowmass 2013: Snowmass on the Mississippi, arXiv:1311.0029.
  8. D. Antypas et al., New horizons: Scalar and vector ultralight dark matter, arXiv:2203.14915.
  9. S. Weinberg, A new light boson?, Phys. Rev. Lett. 40, 223 (1978).
  10. F. Wilczek, Problem of strong P and T invariance in the presence of instantons, Phys. Rev. Lett. 40, 279 (1978).
  11. L. Di Luzio, M. Giannotti, E. Nardi, and L. Visinelli, The landscape of QCD axion models, Phys. Rep. 870, 1 (2020).
  12. A. Arvanitaki, S. Dimopoulos, S. Dubovsky, N. Kaloper, and J. March-Russell, String axiverse, Phys. Rev. D 81, 123530 (2010).
  13. P. Arias, D. Cadamuro, M. Goodsell, J. Jaeckel, J. Redondo, and A. Ringwald, WISPy cold dark matter, J. Cosmol. Astropart. Phys. 06 (2012) 013.
  14. A. Ringwald, Axions and Axion-Like Particles, in 49th Rencontres de Moriond on Electroweak Interactions and Unified Theories (2014), pp. 223–230.
  15. E. G. M. Ferreira, Ultra-light dark matter, Astron. Astrophys. Rev. 29, 7 (2021).
  16. J. Jaeckel, A force beyond the Standard Model—Status of the quest for hidden photons, Frascati Phys. Ser. 56, 172 (2012).
  17. M. Fabbrichesi, E. Gabrielli, and G. Lanfranchi, The dark photon, The Physics of the Dark Photon (Springer, Cham, 2020).
  18. A. Caputo, A. J. Millar, C. A. J. O’Hare, and E. Vitagliano, Dark photon limits: A handbook, Phys. Rev. D 104, 095029 (2021).
  19. M. A. Gorji, M. Sasaki, and T. Suyama, Dark matter from inflationary quantum fluctuations, J. Cosmol. Astropart. Phys. 10 (2025) 110.
  20. D. Blas, J. Carlton, and C. McCabe, Massive graviton dark matter searches with long-baseline atom interferometers, Phys. Rev. D 111, 115020 (2025).
  21. M. A. Gorji, Spin-2 dark matter from inflation, J. Cosmol. Astropart. Phys. 11 (2023) 081.
  22. P. W. Graham, J. Mardon, and S. Rajendran, Vector dark matter from inflationary fluctuations, Phys. Rev. D 93, 103520 (2016).
  23. A. J. Long and L.-T. Wang, Dark photon dark matter from a network of cosmic strings, Phys. Rev. D 99, 063529 (2019).
  24. N. Kitajima and K. Nakayama, Dark photon dark matter from cosmic strings and gravitational wave background, J. High Energy Phys. 08 (2023) 068.
  25. H.-Y. Zhang, P. Arias, A. Cheek, E. D. Schiappacasse, L. Visinelli, and L. Roszkowski, Dark photon dark matter from flattened axion potentials, J. High Energy Phys. 10 (2025) 142.
  26. M. Jain and M. A. Amin, Polarized solitons in higher-spin wave dark matter, Phys. Rev. D 105, 056019 (2022).
  27. H.-Y. Zhang, M. Jain, and M. A. Amin, Polarized vector oscillons, Phys. Rev. D 105, 096037 (2022).
  28. H.-Y. Zhang, Unified view of scalar and vector dark matter solitons, J. High Energy Phys. 04 (2025) 174.
  29. M. Gorghetto, E. Hardy, J. March-Russell, N. Song, and S. M. West, Dark photon stars: Formation and role as dark matter substructure, J. Cosmol. Astropart. Phys. 08 (2022) 018.
  30. M. A. Amin, M. Jain, R. Karur, and P. Mocz, Small-scale structure in vector dark matter, J. Cosmol. Astropart. Phys. 08 (2022) 014.
  31. M. Jain, M. A. Amin, J. Thomas, and W. Wanichwecharungruang, Kinetic relaxation and Bose-star formation in multicomponent dark matter, Phys. Rev. D 108, 043535 (2023).
  32. D. G. Levkov, A. G. Panin, and I. I. Tkachev, Gravitational Bose-Einstein condensation in the kinetic regime, Phys. Rev. Lett. 121, 151301 (2018).
  33. M. P. Hertzberg, E. D. Schiappacasse, and T. T. Yanagida, Axion star nucleation in dark minihalos around primordial black holes, Phys. Rev. D 102, 023013 (2020).
  34. Z. Yin and L. Visinelli, Axion star condensation around primordial black holes and microlensing limits, J. Cosmol. Astropart. Phys. 10 (2024) 013.
  35. E. D. Schiappacasse, Dark spin-2 field solitons as a source of electromagnetic radiation, J. Cosmol. Astropart. Phys. 08 (2025) 085.
  36. M. A. Amin, A. J. Long, and E. D. Schiappacasse, Photons from dark photon solitons via parametric resonance, J. Cosmol. Astropart. Phys. 05 (2023) 015.
  37. E. Petroff, E. D. Barr, A. Jameson, E. F. Keane, M. Bailes, M. Kramer, V. Morello, D. Tabbara, and W. van Straten, FRBCAT: The fast radio burst catalogue, Pub. Astron. Soc. Aust. 33, e045 (2016).
  38. J. I. Katz, Fast radio bursts, Prog. Part. Nucl. Phys. 103, 1 (2018).
  39. E. Petroff, J. W. T. Hessels, and D. R. Lorimer, Fast radio bursts, Astron. Astrophys. Rev. 27, 4 (2019).
  40. D. W. P. Amaral, E. D. Schiappacasse, and H.-Y. Zhang, Constraining dark photon dark matter with radio silence from soliton mergers around supermassive black holes, arXiv:2509.08932.
  41. P. Adshead and K. D. Lozanov, Self-gravitating vector dark matter, Phys. Rev. D 103, 103501 (2021).
  42. M. A. Amin, A. J. Long, Z.-G. Mou, and P. Saffin, Dipole radiation and beyond from axion stars in electromagnetic fields, J. High Energy Phys. 06 (2021) 182.
  43. B. Holdom, Two U(1)’s and Epsilon charge shifts, Phys. Lett. 166B, 196 (1986).
  44. R. Foot and X.-G. He, Comment on Z Z-prime mixing in extended gauge theories, Phys. Lett. B 267, 509 (1991).
  45. E. D. Schiappacasse and M. P. Hertzberg, Analysis of dark matter axion clumps with spherical symmetry, J. Cosmol. Astropart. Phys. 01 (2018) 037; 03 (2018) E01(E).
  46. X. Du, D. J. E. Marsh, M. Escudero, A. Benson, D. Blas, C. K. Pooni, and M. Fairbairn, Soliton merger rates and enhanced axion dark matter decay, Phys. Rev. D 109, 043019 (2024).
  47. E. D. Carlson and W. D. Garretson, Photon to pseudoscalar conversion in the interstellar medium, Phys. Lett. B 336, 431 (1994).
  48. G. C. Wick, The evaluation of the collision matrix, Phys. Rev. 80, 268 (1950).
  49. M. A. Amin, M. P. Hertzberg, D. I. Kaiser, and J. Karouby, Nonperturbative dynamics of reheating after inflation: A review, Int. J. Mod. Phys. D 24, 1530003 (2015).
  50. M. J. Bentum, M. K. Verma, R. T. Rajan, A. J. Boonstra, C. J. M. Verhoeven, E. K. A. Gill, A. J. van der Veen, H. Falcke, M. K. Wolt, B. Monna, S. Engelen, J. Rotteveel, and L. I. Gurvits, A roadmap towards a space-based radio telescope for ultra-low frequency radio astronomy, Adv. Space Res. 65, 856 (2020).
  51. R. T. Rajan, A.-J. Boonstra, M. Bentum, M. Klein-Wolt, F. Belien, M. Arts, N. Saks, and A.-J. van der Veen, Space-based aperture array for ultra-long wavelength radio astronomy, Exp. Astron. 41, 271 (2016).
  52. R. T. Rajan, S. Engelen, M. Bentum, and C. Verhoeven, Orbiting low frequency array for radio astronomy, in Aerospace Conference (IEEE, 2011).
  53. G. Choi and E. D. Schiappacasse, PBH assisted search for QCD axion dark matter, J. Cosmol. Astropart. Phys. 09 (2022) 072.
  54. P. Goldreich and W. H. Julian, Pulsar electrodynamics, Astrophys. J. 157, 869 (1969).
  55. L. Ferrario, D. de Martino, and B. T. Gänsicke, Magnetic white dwarfs, Space Sci. Rev. 191, 111 (2015).
  56. A. J. Millar, S. Baum, M. Lawson, and M. C. D. Marsh, Axion-photon conversion in strongly magnetised plasmas, J. Cosmol. Astropart. Phys. 11 (2021) 013.
  57. J. W. Foster, Y. Kahn, O. Macias, Z. Sun, R. P. Eatough, V. I. Kondratiev, W. M. Peters, C. Weniger, and B. R. Safdi, Green bank and Effelsberg radio telescope searches for axion dark matter conversion in neutron star magnetospheres, Phys. Rev. Lett. 125, 171301 (2020).
  58. M. Leroy, M. Chianese, T. D. P. Edwards, and C. Weniger, Radio signal of axion-photon conversion in neutron stars: A ray tracing analysis, Phys. Rev. D 101, 123003 (2020).
  59. B. R. Safdi, Z. Sun, and A. Y. Chen, Detecting axion dark matter with radio lines from neutron star populations, Phys. Rev. D 99, 123021 (2019).
  60. F. P. Huang, K. Kadota, T. Sekiguchi, and H. Tashiro, Radio telescope search for the resonant conversion of cold dark matter axions from the magnetized astrophysical sources, Phys. Rev. D 97, 123001 (2018).
  61. M. S. Pshirkov and S. B. Popov, Conversion of Dark matter axions to photons in magnetospheres of neutron stars, J. Exp. Theor. Phys. 108, 384 (2009).
  62. S. J. Witte, S. Baum, M. Lawson, M. C. D. Marsh, A. J. Millar, and G. Salinas, Transient radio lines from axion miniclusters and axion stars, Phys. Rev. D 107, 063013 (2023).
  63. S. Nurmi, E. D. Schiappacasse, and T. T. Yanagida, Radio signatures from encounters between neutron stars and QCD-axion minihalos around primordial black holes, J. Cosmol. Astropart. Phys. 09 (2021) 004.
  64. T. D. P. Edwards, B. J. Kavanagh, L. Visinelli, and C. Weniger, Transient radio signatures from neutron star encounters with QCD axion miniclusters, Phys. Rev. Lett. 127, 131103 (2021).
  65. J. H. Buckley, P. S. B. Dev, F. Ferrer, and F. P. Huang, Fast radio bursts from axion stars moving through pulsar magnetospheres, Phys. Rev. D 103, 043015 (2021).
  66. A. J. Long and E. D. Schiappacasse, Resonant conversion of axion dark radiation into terahertz electromagnetic radiation in a neutron star magnetosphere, Phys. Rev. D 110, 103020 (2024).
  67. C.-A. Faucher-Giguere and V. M. Kaspi, Birth and evolution of isolated radio pulsars, Astrophys. J. 643, 332 (2006).
  68. L. G. Althaus, A. H. Córsico, J. Isern, and E. García-Berro, Evolutionary and pulsational properties of white dwarf stars, Astron. Astrophys. Rev. 18, 471 (2010).
  69. G. Fontaine, P. Brassard, and P. Bergeron, The potential of white dwarf cosmochronology, Publ. Astron. Soc. Pac. 113, 409 (2001).
  70. A. Kawka, S. Vennes, G. D. Schmidt, D. T. Wickramasinghe, and R. Koch, Spectropolarimetric survey of hydrogen-rich white dwarf stars, Astrophys. J. 654, 499 (2007).
  71. N. Giammichele, P. Bergeron, and P. Dufour, Know your neighborhood: A detailed model atmosphere analysis of nearby white dwarfs, Astrophys. J. Suppl. Ser. 199, 29 (2012).
  72. E. M. Sion, J. B. Holberg, T. D. Oswalt, G. P. McCook, R. Wasatonic, and J. Myszka, The white dwarfs within 25 pc of the sun: Kinematics and spectroscopic subtypes, Astron. J. 147, 129 (2014).
  73. J. Liebert, P. Bergeron, and J. B. Holberg, The True incidence of magnetism among field white dwarfs, Astron. J. 125, 348 (2003).
  74. S. O. Kepler, I. Pelisoli, S. Jordan, S. J. Kleinman, D. Koester, B. Külebi, V. Peçanha, B. G. Castanheira, A. Nitta, J. E. S. Costa, D. E. Winget, A. Kanaan, and L. Fraga, Magnetic white dwarf stars in the Sloan Digital Sky Survey, Mon. Not. R. Astron. Soc. 429, 2934 (2013).
  75. S. O. Kepler, I. Pelisoli, D. Koester, G. Ourique, A. D. Romero, N. Reindl, S. J. Kleinman, D. J. Eisenstein, A. D. M. Valois, and L. A. Amaral, New white dwarf and subdwarf stars in the Sloan Digital Sky Survey data release 12, Mon. Not. R. Astron. Soc. 455, 3413 (2016).
  76. L. Ferrario and D. T. Wickramasinghe, Magnetic fields and rotation in white dwarfs and neutron stars, Mon. Not. R. Astron. Soc. 356, 615 (2005).
  77. J. F. Acevedo, R. K. Leane, and L. Santos-Olmsted, Milky Way white dwarfs as sub-GeV to multi-TeV dark matter detectors, J. Cosmol. Astropart. Phys. 03 (2023) 042.
  78. S. Observatory, Ska1 system baseline design v2 (2016).
  79. R. Beck, Galactic and extragalactic magnetic fields, Space Sci. Rev. 99, 243 (2001).
  80. C. Faucher-Giguere and V. M. Kaspi, Birth and evolution of isolated radio pulsars, Astrophys. J. 643, 332 (2006).
  81. D. T. Wickramasinghe and L. Ferrario, Magnetism in isolated and binary white dwarfs, Publ. Astron. Soc. Pac. 112, 873 (2000).
  82. M. A. Belyaev and K. Parfrey, Spatial distribution of pair production over the pulsar polar cap, Astrophys. J. 830, 119 (2016).
  83. F. H. Shu, The Physical Universe: An Introduction to Astronomy (University Science Books, California, 1982).
  84. J. Binney and S. Tremaine, Galactic dynamics (Princeton University Press, Princeton, NJ, 2011).
  85. J. Kormendy and D. Richstone, Inward bound—The search for supermassive black holes in galactic nuclei, Annu. Rev. Astron. Astrophys. 33, 581 (1995).
  86. J. Kormendy and L. C. Ho, Coevolution (Or Not) of supermassive black holes and host galaxies, Annu. Rev. Astron. Astrophys. 51, 511 (2013).
  87. P. Gondolo and J. Silk, Dark matter annihilation at the galactic center, Phys. Rev. Lett. 83, 1719 (1999).
  88. G. Bertone, G. Sigl, and J. Silk, Annihilation radiation from a dark matter spike at the galactic center, Mon. Not. R. Astron. Soc. 337, 98 (2002).
  89. Z.-C. Zhang, H.-C. Yuan, and Y. Tang, Universal density and velocity distributions of dark matter around massive black holes, Phys. Rev. D 112, 043025 (2025).
  90. M. H. Chan and C. M. Lee, The first robust evidence showing a dark matter density spike around the supermassive black hole in OJ 287, Astrophys. J. Lett. 962, L40 (2024).
  91. P. Gondolo, Either neutralino dark matter or cuspy dark halos, Phys. Lett. B 494, 181 (2000).
  92. B. D. Fields, S. L. Shapiro, and J. Shelton, Galactic center gamma-ray excess from dark matter annihilation: Is there a black hole spike?, Phys. Rev. Lett. 113, 151302 (2014).
  93. T.-C. Liu, J.-G. Cheng, Y.-F. Liang, and E.-W. Liang, Search for gamma-ray line signals around the black hole at the galactic center with DAMPE observation, Sci. China Phys. Mech. Astron. 65, 269512 (2022).
  94. S. Balaji, D. Sachdeva, F. Sala, and J. Silk, Dark matter spikes around Sgr A* in γ-rays, J. Cosmol. Astropart. Phys. 08 (2023) 063.
  95. D. W. P. Amaral and E. D. Schiappacasse, Rescuing the primordial black holes all-dark matter hypothesis from the fast radio bursts tension, Phys. Rev. D 110, 083532 (2024).
  96. K. Kainulainen, S. Nurmi, E. D. Schiappacasse, and T. T. Yanagida, Can primordial black holes as all dark matter explain fast radio bursts?, Phys. Rev. D 104, 123033 (2021).
  97. S. Gillessen, P. M. Plewa, F. Eisenhauer, R. Sari, I. Waisberg, M. Habibi, O. Pfuhl, E. George, J. Dexter, S. von Fellenberg, T. Ott, and R. Genzel, An update on monitoring stellar orbits in the galactic center, Astrophys. J. 837, 30 (2017).
  98. S. Fakhry, S. Gholamhoseinian, and M. Farhang, Compact binary merger rate with modified gravity in dark matter spikes, Astrophys. J. 976, 248 (2024).
  99. J. Diemand, M. Kuhlen, P. Madau, M. Zemp, B. Moore, D. Potter, and J. Stadel, Clumps and streams in the local dark matter distribution, Nature (London) 454, 735 (2008).
  100. J. F. Navarro, A. Ludlow, V. Springel, J. Wang, M. Vogelsberger, S. D. M. White, A. Jenkins, C. S. Frenk, and A. Helmi, The diversity and similarity of cold dark matter halos, Mon. Not. R. Astron. Soc. 402, 21 (2010).
  101. M. Gustafsson, M. Fairbairn, and J. Sommer-Larsen, Baryonic pinching of galactic dark matter haloes, Phys. Rev. D 74, 123522 (2006).
  102. N. Neumayer, A. Seth, and T. Böker, Nuclear star clusters, Astron. Astrophys. Rev. 28, 4 (2020).
  103. M. Freitag, P. Amaro-Seoane, and V. Kalogera, Stellar remnants in galactic nuclei: Mass segregation, Astrophys. J. 649, 91 (2006).
  104. E. Gallego-Cano, R. Schödel, H. Dong, F. Nogueras-Lara, A. T. Gallego-Calvente, P. Amaro-Seoane, and H. Baumgardt, The distribution of stars around the Milky Way’s central black hole. I. Deep star counts, Astron. Astrophys. 609, A26 (2018).
  105. R. Schödel, E. Gallego-Cano, H. Dong, F. Nogueras-Lara, A. T. Gallego-Calvente, P. Amaro-Seoane, and H. Baumgardt, The distribution of stars around the Milky Way’s central black hole. II. Diffuse light from sub-giants and dwarfs, Astron. Astrophys. 609, A27 (2018).
  106. M. Habibi, S. Gillessen, O. Pfuhl, F. Eisenhauer, P. M. Plewa, S. von Fellenberg, F. Widmann, T. Ott, F. Gao, I. Waisberg, M. Bauböck, A. Jimenez-Rosales, J. Dexter, P. T. de Zeeuw, and R. Genzel, Spectroscopic detection of a cusp of late-type stars around the central black hole in the Milky Way, Astrophys. J. Lett. 872, L15 (2019).
  107. C. Hailey, K. Mori, F. Bauer et al., A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy, Nature (London) 556, 70 (2018).
  108. J. N. Bahcall and R. A. Wolf, Star distribution around a massive black hole in a globular cluster, Astrophys. J. 209, 214 (1976).
  109. W. Dehnen, A family of potential-density pairs for spherical galaxies and bulges, Mon. Not. R. Astron. Soc. 265, 250 (1993).
  110. S. Tremaine, D. O. Richstone, Y.-I. Byun, A. Dressler, S. M. Faber, C. Grillmair, J. Kormendy, and T. R. Lauer, A Family of models for spherical stellar systems, Astron. J. 107, 634 (1994).
  111. J. F. Acevedo, R. K. Leane, and L. Santos-Olmsted, Milky Way white dwarfs as sub-GeV to multi-TeV dark matter detectors, J. Cosmol. Astropart. Phys. 03 (2024) 042.
  112. O. Y. Gnedin and J. R. Primack, Dark matter profile in the galactic center, Phys. Rev. Lett. 93, 061302 (2004).
  113. D. Merritt, Evolution of the dark matter distribution at the galactic center, Phys. Rev. Lett. 92, 201304 (2004).
  114. S. L. Shapiro and D. C. Heggie, Effect of stars on the dark matter spike around a black hole: A tale of two treatments, Phys. Rev. D 106, 043018 (2022).
  115. P. Ullio, H. Zhao, and M. Kamionkowski, Dark-matter spike at the galactic center?, Phys. Rev. D 64, 043504 (2001).
  116. D. Merritt, M. Milosavljević, L. Verde, and R. Jimenez, Dark matter spikes and annihilation radiation from the galactic center, Phys. Rev. Lett. 88, 191301 (2002).
  117. D. Merritt and M. Y. Poon, Chaotic loss cones and black hole fueling, Astrophys. J. 606, 788 (2004).
  118. J. P. Ostriker, Collisional dark matter and the origin of massive black holes, Phys. Rev. Lett. 84, 5258 (2000).

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Phys. Rev. D 113, 123537– Published 22 June, 2026
  • Received 22 February 2026
  • Accepted 12 May 2026
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