0000000000408403
AUTHOR
Fiorenza Donato
Galactic synchrotron emission from astrophysical electrons
The interaction between the galactic magnetic field and the non-thermal population of electrons is responsible for a large part of the radio sky from 10 MHz up to several GHz. This population is mostly composed of electrons with primary and secondary origin. Cosmic ray propagation models describe their evolution in space and energy, and allow to study the impact on the radio sky in intensity and morphology at different frequencies. We consider different propagation models and test their compatibility with available radio maps. We find models highly consistent both with B/C data, the local electron flux and synchrotron emission observations. The resulting constraints on propagation models co…
Conservative upper limits on WIMP annihilation cross section from Fermi-LAT $γ$-rays
The spectrum of an isotropic extragalactic {\gamma}-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement of the annihilation cross section are set as well. Finally, we consider models for DM annihilation depending on the inver…
Conservative upper limits on WIMP annihilation cross section from Fermi-LAT γ rays
The spectrum of an isotropic extragalactic {\gamma}-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement of the annihilation cross section are set as well. Finally, we consider models for DM annihilation depending on the inver…
Extending the DAMA annual-modulation region by inclusion of the uncertainties in astrophysical velocities
The original annual-modulation region, singled out by the DAMA/NaI experiment for direct detection of WIMPs, is extended by taking into account the uncertainties in the galactic astrophysical velocities. Also the effect due to a possible bulk rotation for the dark matter halo is considered. We find that the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L. with a further extension in the upper bound, when a possible bulk rotation of the dark matter halo is taken into account. We show that the DAMA results, when interpreted in the framework of the Minimal Supersymmetric extension of the Standard Model, are consistent with a relic neutralino as a dominant componen…
Interpretation of AMS-02 electrons and positrons data
We perform a combined analysis of the recent AMS-02 data on electrons, positrons, electrons plus positrons and positron fraction, in a self-consistent framework where we realize a theoretical modeling of all the astrophysical components that can contribute to the observed fluxes in the whole energy range. The primary electron contribution is modeled through the sum of an average flux from distant sources and the fluxes from the local supernova remnants in the Green catalog. The secondary electron and positron fluxes originate from interactions on the interstellar medium of primary cosmic rays, for which we derive a novel determination by using AMS-02 proton and helium data. Primary positron…
Radio data and synchrotron emission in consistent cosmic ray models
It is well established that phenomenological two-zone diffusion models of the galactic halo can very well reproduce cosmic-ray nuclear data and the observed antiproton flux. Here, we consider lepton propagation in such models and compute the expected galactic population of electrons, as well as the diffuse synchrotron emission that results from their interaction with galactic magnetic fields. We find models in agreement not only with cosmic ray data but also with radio surveys at essentially all frequencies. Requiring such a globally consistent description strongly disfavors very large ($L\gtrsim 15$ kpc) and, even stronger, small ($L\lesssim 1$ kpc) effective diffusive halo sizes. This has…