Hidden-sector dark matter achieves standard thermal relic abundance via early decoupling with temperature-matched freeze-out, enabling WIMP-like cross sections without late-time thermalization.
Two Emission Mechanisms in the Fermi Bubbles: A Possible Signal of Annihilating Dark Matter
4 Pith papers cite this work. Polarity classification is still indexing.
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abstract
We study the variation of the spectrum of the Fermi Bubbles with Galactic latitude. Far from the Galactic plane (|b| > 30 degrees), the observed gamma-ray emission is nearly invariant with latitude, and is consistent with arising from inverse Compton scattering of the interstellar radiation field by cosmic-ray electrons with an approximately power-law spectrum. The same electrons in the presence of microgauss-scale magnetic fields can also generate the the observed microwave "haze". At lower latitudes (b < 20 degrees), in contrast, the spectrum of the emission correlated with the Bubbles possesses a pronounced spectral feature peaking at 1-4 GeV (in E^2 dN/dE) which cannot be generated by any realistic spectrum of electrons. Instead, we conclude that a second (non-inverse-Compton) emission mechanism must be responsible for the bulk of the low-energy, low-latitude emission. This second component is spectrally similar to the excess GeV emission previously reported from the Galactic Center (GC), and also appears spatially consistent with a luminosity per volume falling approximately as r^-2.4, where r is the distance from the GC. We argue that the spectral feature visible in the low-latitude Bubbles is the extended counterpart of the GC excess, now detected out to at least 2-3 kpc from the GC. The spectrum and angular distribution of the signal is consistent with that predicted from ~10 GeV dark matter particles annihilating to leptons, or from ~50 GeV dark matter particles annihilating to quarks, following a distribution similar to the canonical Navarro-Frenk-White (NFW) profile. We also consider millisecond pulsars as a possible astrophysical explanation for the signal, as observed millisecond pulsars possess a spectral cutoff at approximately the required energy. Any such scenario would require a large population of unresolved millisecond pulsars extending at least 2-3 kpc from the GC.
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Cosmic ray protons scattering off dark matter produce the Galactic Center gamma-ray excess through inelastic up-scattering followed by decay or direct elastic 2-to-3 photon production.
Reports ~20% projected polarization in synchrotron and thermal dust emission from Fermi bubbles, with fields parallel to edges, and attributes larger lobes to an older supermassive black hole outburst.
Updated constraints on two simplified dark matter models for the Galactic Center Excess leave unconstrained parameter space after applying recent multi-experiment data.
citing papers explorer
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WIMP-like Dark Matter Without Thermalization At Freeze-Out
Hidden-sector dark matter achieves standard thermal relic abundance via early decoupling with temperature-matched freeze-out, enabling WIMP-like cross sections without late-time thermalization.
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Producing the GeV Galactic Center Excess via Cosmic Ray-Dark Matter Scattering
Cosmic ray protons scattering off dark matter produce the Galactic Center gamma-ray excess through inelastic up-scattering followed by decay or direct elastic 2-to-3 photon production.
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Detection of polarized Fermi-bubble synchrotron and dust emission
Reports ~20% projected polarization in synchrotron and thermal dust emission from Fermi bubbles, with fields parallel to edges, and attributes larger lobes to an older supermassive black hole outburst.
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Testing Viability of Benchmark Dark Matter Models for the Galactic Center Excess
Updated constraints on two simplified dark matter models for the Galactic Center Excess leave unconstrained parameter space after applying recent multi-experiment data.