Possible Evidence for MeV Dark Matter in Dwarf Spheroidals

Hooper, Dan; Ferrer, Francesc; Bœhm, Céline; Silk, Joseph; Paul, Jacques; Evans, N. W.; Cassé, Michel

doi:10.1103/physrevlett.93.161302

Cited by 71 publications

(70 citation statements)

References 35 publications

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“…To differentiate such a scenario from more exotic sources, such as light decaying particles, future tests must be made [31]. Additionally, if decaying axinos are the source of the 511 keV emission, signatures of supersymmetry, and R-parity violation will likely be observed at the LHC.…”

Section: Discussionmentioning

confidence: 99%

Possible evidence for axino dark matter in the galactic bulge

2004

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Recently, the SPI spectrometer on the INTEGRAL satellite observed strong 511 keV line emission from the galactic bulge. Although the angular distribution (spherically symmetric with width of ∼ 9 • ) of this emission is difficult to account for with traditional astrophysical scenarios, light dark matter particles could account for the observation. In this letter, we consider the possibility that decaying axinos in an R-parity violating model of supersymmetry may be the source of this emission. We find that ∼ 1 − 300 MeV axinos with R-parity violating couplings can naturally produce the observed emission. 95.35.+d, 14.80.Ly, 07.85.Fv,14.80.Mz

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Section: Discussionmentioning

confidence: 99%

Possible evidence for axino dark matter in the galactic bulge

2004

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“…That dSphs make good candidates for DM annihilation detection has been much discussed before, especially for the "classical", or pre-SDSS, dSphs [62,110,142,143,144,145]. The annihilation signal coming from Draco has been the subject of much research in recent years because of its relative proximity to the Earth [65,110,144,146,147,148,149,150].…”

Section: Predicted Annihilation Signals For Dwarf Spheroidalsmentioning

confidence: 99%

Substructure boosts to dark matter annihilation from Sommerfeld enhancement

Bovy

2009

Phys. Rev. D

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The recently introduced Sommerfeld enhancement of the dark matter annihilation cross section has important implications for the detection of dark matter annihilation in subhalos in the Galactic halo. In addition to the boost to the dark matter annihilation cross section from the high densities of these subhalos with respect to the main halo, an additional boost caused by the Sommerfeld enhancement results from the fact that they are kinematically colder than the Galactic halo. If we further believe the generic prediction of CDM that in each subhalo there is an abundance of substructure which is approximately self-similar to that of the Galactic halo, then I show that additional boosts coming from the density enhancements of these small substructures and their small velocity dispersions enhance the dark matter annihilation cross section even further. I find that very large boost factors (10 5 to 10 9 ) are obtained in a large class of models. The implications of these boost factors for the detection of dark matter annihilation from dwarf Spheroidal galaxies in the Galactic halo are such that, generically, they outshine the background gamma-ray flux and are detectable by the Fermi Gamma-ray Space Telescope.

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“…This proposal explains the measured injection rate of positrons as well as morphology of the signal extended over the bulge region. Intriguingly, popular astronomical sources such as supernovae again seem to fail to satisfy the observational constraints [17]. Motivated by this idea, in the previous paper [18] we have calculated the γ-ray background of redshifted 511 keV lines from extragalactic halos distributed over a large redshift range.…”

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confidence: 99%

Dark matter annihilation: The origin of cosmic gamma-ray background at 1–20 MeV

Ahn

Komatsu

2005

Phys. Rev. D

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The origin of the cosmic γ-ray background at 1-20 MeV remains a mystery. We show that γ-ray emission accompanying annihilation of 20 MeV dark matter particles explains most of the observed signal. Our model satisfies all of the current observational constraints, and naturally provides the origin of "missing" γ-ray background at 1-20 MeV and 511 keV line emission from the Galactic center. We conclude that γ-ray observations support the existence of 20 MeV dark matter particles. Improved measurements of the γ-ray background in this energy band undoubtedly test our proposal.PACS numbers: 95.35.+d, 95.85.Nv, 95.85.Pw What is the origin of the cosmic γ-ray background? It is usually understood that the cosmic γ-ray background is a superposition of unresolved astronomical γ-ray sources distributed in the universe. Active Galactic Nuclei (AGNs) alone explain most of the background light in two energy regions: ordinary (but obscured by intervening hydrogen gas) AGNs account for the lowenergy ( < ∼ 0.5 MeV) spectrum [1, 2, 3], whereas beamed AGNs (known as Blazars) account for the high-energy ( > ∼ 20 MeV) spectrum [4,5,6]. There is, however, a gap between these two regions. While historically supernovae have been a leading candidate for the background up to 4 MeV [7,8,9,10], recent studies [11,12] show that the supernova contribution is an order of magnitude lower than observed. The spectrum at 4-20 MeV also remains unexplained (for a review on this subject, see [13]). It is not very easy to explain such high-energy background light by astronomical sources without AGNs or supernovae.So, what is the origin of the cosmic γ-ray background at 0.5-20 MeV? On energetics, a decay or annihilation of particles having mass in the range of 0.5 MeV < ∼ m X < ∼ 20 MeV would produce the background light in the desired energy band. Since both lower-and higher-energy spectra are already accounted for by AGNs almost entirely, too lighter or too heavier (e.g., neutralinos) particles should be excluded. Is there any evidence or reason that such particles should exist? The most compelling evidence comes from 511 keV line emission from the central part of our Galaxy, which has been detected and mapped by the SPI spectrometer on the INTErnational Gamma-Ray Astrophysics Laboratory (INTE-GRAL) satellite [14,15]. This line should be produced by annihilation of electron-positron pairs, and one of the possible origins is the dark matter particles annihilating into electron-positron pairs [16]. This proposal explains the measured injection rate of positrons as well as morphology of the signal extended over the bulge region. Intriguingly, popular astronomical sources such as supernovae again seem to fail to satisfy the observational constraints [17]. Motivated by this idea, in the previous paper [18] we have calculated the γ-ray background of redshifted 511 keV lines from extragalactic halos distributed over a large redshift range. We have shown that the annihilation signal makes a substantial contribution to the low-energy spectrum at < 0.511 Me...

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Possible Evidence for MeV Dark Matter in Dwarf Spheroidals

Cited by 71 publications

References 35 publications

Possible evidence for axino dark matter in the galactic bulge

Possible evidence for axino dark matter in the galactic bulge

Substructure boosts to dark matter annihilation from Sommerfeld enhancement

Dark matter annihilation: The origin of cosmic gamma-ray background at 1–20 MeV

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