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.
Fermi-LAT Observations of High-Energy Gamma-Ray Emission Toward the Galactic Center
9 Pith papers cite this work. Polarity classification is still indexing.
abstract
The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission towards the Galactic centre (GC) in high-energy gamma-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1-100 GeV from a $15^\circ \times 15^\circ$ region about the direction of the GC, and implications for the interstellar emissions produced by cosmic ray (CR) particles interacting with the gas and radiation fields in the inner Galaxy and for the point sources detected. Specialised interstellar emission models (IEMs) are constructed that enable separation of the gamma-ray emission from the inner $\sim 1$ kpc about the GC from the fore- and background emission from the Galaxy. Based on these models, the interstellar emission from CR electrons interacting with the interstellar radiation field via the inverse Compton (IC) process and CR nuclei inelastically scattering off the gas producing gamma-rays via $\pi^0$ decays from the inner $\sim 1$ kpc is determined. The IC contribution is found to be dominant in the region and strongly enhanced compared to previous studies. A catalog of point sources for the $15^\circ \times 15^\circ$ region is self-consistently constructed using these IEMs: the First Fermi-LAT Inner Galaxy point source Catalog (1FIG). After subtracting the interstellar emission and point-source contributions from the data a residual is found that is a sub-dominant fraction of the total flux. If spatial templates that peak toward the GC are used to model the positive residual and included in the total model for the $15^\circ \times 15^\circ$ region, the agreement with the data improves, but none of the additional templates account for all of the residual structure. The spectrum of the positive residual modelled with these templates has a strong dependence on the choice of IEM. [Abridged]
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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.
Joint prompt and inverse-Compton modeling of MSP-injected e± yields strong upper limits on η_e/η_γ from recent Fermi-LAT GCE spectra that exceed MAGIC globular-cluster bounds.
WIMP models for the Galactic Center Excess survive only in finely tuned resonant funnels with portal couplings around 10^-4, with leptophilic vectors and pseudoscalar portals remaining most viable after current bounds.
The thesis presents a new 3-to-2 freezeout mechanism, bound-state effects on searches, a new axion interferometric search, reionization assessments, 21-cm constraints, and the DarkHistory code for ionization and thermal histories.
Filtering unidentified Fermi sources and comparing to repopulated VL-II simulations yields upper limits of 4e-26 cm3/s (10 GeV) and 5e-25 cm3/s (100 GeV) on tau-pair annihilation.
LHC mono-W/Z searches with a new channel-separation method can exclude large ranges of neutral and charged mass splittings in the 70-75 GeV IDM dark matter scenario that fits astrophysical excesses.
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A Comprehensive Study of WIMP Models Explaining the Fermi-LAT Galactic Center Excess
WIMP models for the Galactic Center Excess survive only in finely tuned resonant funnels with portal couplings around 10^-4, with leptophilic vectors and pseudoscalar portals remaining most viable after current bounds.