An Excited Dark Matter Solution to the MeV Galactic Center Excesses
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866909991350304768 |
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| author | Balaji, Shyam Cleaver, Damon Luque, Pedro De la Torre |
| author_facet | Balaji, Shyam Cleaver, Damon Luque, Pedro De la Torre |
| contents | Recent COMPTEL data analysis reveals a $\sim$ 2 MeV continuum excess whose spatial distribution closely matches the long-standing 511 keV line observed by INTEGRAL/SPI, indicating a common population of low-energy positrons that is difficult to reconcile with known astrophysical sources or standard thermal dark matter (DM). We show that a minimal Excited Dark Matter (XDM) model naturally explains these features. In this scenario a DM particle $χ$ is inelastically upscattered into an excited state $χ^*$, followed by de-excitation $χ^*\toχe^+ e^-$ producing $\sim$2 MeV positrons that reproduce the 511 keV line morphology and the COMPTEL MeV continuum. Using a full cosmic-ray (CR) propagation treatment, we obtain an excellent fit for $m_χ\simeq$ 1.5 TeV DM particle with mass-splitting $Δm =m_{χ^*}-m_χ\simeq$ 4 MeV for an inelastic geometric scattering cross section of $σ_\textrm{mr}= 3-4\times 10^{-23}\,\textrm{cm}^2$. The same positrons supply a substantial, radially flat contribution to the anomalous Central Molecular Zone (CMZ) ionization rate. This is the first unified treatment of XDM-induced positrons across all three observables, yielding correlated MeV signatures testable by upcoming missions targeting the Galactic MeV band. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_13797 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | An Excited Dark Matter Solution to the MeV Galactic Center Excesses Balaji, Shyam Cleaver, Damon Luque, Pedro De la Torre High Energy Physics - Phenomenology High Energy Astrophysical Phenomena Recent COMPTEL data analysis reveals a $\sim$ 2 MeV continuum excess whose spatial distribution closely matches the long-standing 511 keV line observed by INTEGRAL/SPI, indicating a common population of low-energy positrons that is difficult to reconcile with known astrophysical sources or standard thermal dark matter (DM). We show that a minimal Excited Dark Matter (XDM) model naturally explains these features. In this scenario a DM particle $χ$ is inelastically upscattered into an excited state $χ^*$, followed by de-excitation $χ^*\toχe^+ e^-$ producing $\sim$2 MeV positrons that reproduce the 511 keV line morphology and the COMPTEL MeV continuum. Using a full cosmic-ray (CR) propagation treatment, we obtain an excellent fit for $m_χ\simeq$ 1.5 TeV DM particle with mass-splitting $Δm =m_{χ^*}-m_χ\simeq$ 4 MeV for an inelastic geometric scattering cross section of $σ_\textrm{mr}= 3-4\times 10^{-23}\,\textrm{cm}^2$. The same positrons supply a substantial, radially flat contribution to the anomalous Central Molecular Zone (CMZ) ionization rate. This is the first unified treatment of XDM-induced positrons across all three observables, yielding correlated MeV signatures testable by upcoming missions targeting the Galactic MeV band. |
| title | An Excited Dark Matter Solution to the MeV Galactic Center Excesses |
| topic | High Energy Physics - Phenomenology High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2512.13797 |