Related papers: Unstable Relics as a Source of Galactic Positrons
We analyze two dedicated NuSTAR observations with exposure ${\sim}190$ ks located ${\sim}10^\circ$ from the Galactic plane, one above and the other below, to search for x-ray lines from the radiative decay of sterile-neutrino dark matter.…
The AMS-02 experiment confirms the excess of positrons in cosmic rays (CRs) for energy above 10 GeV with respect to the secondary production of positrons in the interstellar medium. This is interpreted as evidence of the existence of a…
We have shown that inflatons with a mass which is calculated to be of the order of $10^{10}\GeV$ can constitute a dominant part of dark matter. They can decay uniquely into a neutrino and antineutrino with a lifetime calculated to be…
We have estimated fluxes of neutrinos and gamma-rays that are generated from decays of charged and neutral pions from a pulsar surrounded by supernova ejecta in our galaxy, including an effect that has not been taken into consideration,…
A recent observation of the 511 keV electron-positron annihilation line from the Galactic bulge has prompted a debate on the origin of the galactic positrons responsible for this emission. Assuming equilibrium between annihilation and…
We study the production of sterile neutrinos in the early universe from $\pi \rightarrow l \nu_s$ shortly after the QCD phase transition in the absence of a lepton asymmetry while including finite temperature corrections to the $\pi$ mass…
We show that the $e^++e^-$ decay of a light scalar boson of mass 1-10 MeV may account for the fluxes of 511 keV gamma ray observed by SPI/INTEGRAL. We argue that candidates of such a light scalar boson is one of the string moduli or a…
We show that the existence of low scale gravity at TeV scale could lead to a direct production of photons with energies above 10^22 eV due to annihilation of ultra high energy neutrinos on relic massive neutrinos of the galactic halo. Air…
The Pierre Auger observatory has presented evidence that the arrival directions of cosmic rays with energies in excess of 6x10^7 TeV may be correlated with nearby active galactic nuclei (AGN). In this context we revisit a suggestion based…
Observations of TeV--PeV-energy cosmic neutrinos by the IceCube observatory have suggested that extragalactic cosmic-ray sources should have an optical depth greater than $\sim$0.01 and contribute to more than 10\% of the observed bulk of…
Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often heavier particles decay into the lightest dark matter particle as the Universe evolves. Here we explore the possibilities that arise if…
Active galactic nuclei (AGN) are known as sources of high energy gamma-rays. The emission probably results from non-thermal radiation of relativistic jets belonging to the AGN. Earlier investigations of these processes have suggested that…
We consider the possibility that the excess of cosmic rays near $\sim 10^{18}$ eV, reported by the AGASA and SUGAR groups from the direction of the Galactic Center, is caused by a young, very fast pulsar in the high density medium. The…
The diffused gamma halo around our Galaxy recently discovered by EGRET could be produced by annihilations of relic neutrinos N (of fourth generation), whose mass is within a narrow range (Mz /2 < M < Mz). Neutrino annihilations in the halo…
It has previously been proposed that annihilating dark matter particles with MeV-scale masses could be responsible for the flux of 511 keV photons observed from the region of the Galactic Bulge. The conventional wisdom, however, is that it…
There is growing evidence for star formation inside outflows of active galactic nuclei (AGNs). The formed stars are injected into bulges and give rise to perturbation of bulges. In this paper, we investigate the issues of non-rotating,…
Solar, atmospheric and reactor neutrino experiments established that neutrinos are massive. It is quite natural then to consider neutrinos as candidate particles for explaining the dark matter in halos around galaxies. We study the…
We study the growth of density perturbations in a universe with unstable dark matter particles. The mass (m_\nu) range 30 eV < m_\nu < 10 keV with lifetimes ($t_d$) in the range 10^7 sec < t_d < 10^16 sec are considered. We calculate the…
The latest results from PAMELA and FERMI experiments confirm the necessity to improve theoretical models of production and propagation of galactic electrons and positrons. There are many possible explanations for the positron excess…
We estimate energy spectra and fluxes at the Earth's surface of the cosmic and Galactic neutrino backgrounds produced by thermonuclear reactions in stars. The extra-galactic component is obtained by combining the most recent estimates of…