ar X iv : a st ro - p h / 98 11 36 1 v 2 2 5 N ov 1 99 8 Cosmic Rays in the Galactic Center Region
نویسندگان
چکیده
EGRET data on the Gamma ray emission from the inner Galaxy have shown a rather flat spectrum. This spectrum extends to about 50 GeV in photon energy. It is usually assumed that these gamma-rays arise from the interactions of cosmic ray nuclei with ambient matter. Cosmic Ray particles have been observed up to 3 10 20 eV, with many arguments suggesting, that up to about 3 10 18 eV they are of Galactic origin. Cosmic ray particles get injected by their sources, presumably supernova explosions. Their injected spectrum is steepened by diffusive losses from the Galaxy to yield the observed spectrum. As cosmic ray particles roam around in the Galactic disk, and finally depart, they encounter molecular clouds and through p-p collisions produce gamma rays from pion decay. The flux and spectrum of these gamma rays is then a clear signature of cosmic rays throughout the Galaxy. Star formation activity peaks in the central region of the Galaxy, around the Galactic Center, the focus of this meeting. Looking then at the gamma ray spectrum of the central region of our Galaxy yields clues as to where the cosmic ray particles interact, and with what spectrum. Using the FLUKA Monte-Carlo, we have modelled this spectrum, and find a best fit for a powerlaw spectrum of cosmic rays with a spectrum of 2.34, rather close to the suggested injection spectrum for supernovae which explode into their own winds. This suggests that most cosmic ray interaction happens near the sources of injection; it has already been shown elsewhere that this is consistent with the spectrum of cosmic ray nuclei derived from spallation. One important consequence is that cosmic ray heating and ionization should be strong in the Galactic Center region.
منابع مشابه
ar X iv : a st ro - p h / 98 11 36 1 v 1 2 3 N ov 1 99 8 Cosmic Rays in the Galactic Center Region
EGRET data on the Gamma ray emission from the inner Galaxy have shown a rather flat spectrum. This spectrum extends to about 50 GeV in photon energy. It is usually assumed that these gamma-rays arise from the interactions of cosmic ray nuclei with ambient matter. Cosmic Ray particles have been observed up to 3 10 20 eV, with many arguments suggesting, that up to about 3 10 18 eV they are of Gal...
متن کاملar X iv : a st ro - p h / 98 11 14 9 v 1 1 0 N ov 1 99 8 The BeppoSAX High Energy Large Area Survey ( HELLAS )
We have surveyed ∼ 50 deg of sky in the largely unexplored 5-10 keV band using the BeppoSAX MECS instrument, finding 180 sources. After correction for the non uniform sky coverage we find about 18 sources deg with F5−10keV > ∼ 5 × 10 erg cm s , and resolve 30-40 % of the hard 5-10 keV Cosmic X-ray Background (XRB). Optical identification of a first small sample of sources show that most (11 out...
متن کاملar X iv : a st ro - p h / 99 11 03 5 v 2 1 9 N ov 1 99 9 Top - Down Models and Extremely High Energy Cosmic Rays
We developed numerical code for calculation of the extragalactic component of the spectra of leptons, nucleons and γ-rays resulting from " top-down " (non-acceleration) models for the case of uniform and isotropic source distribution. We explored two different classes of " top-down " scenarios: the wide earlier investigated class of X particles coming from collapse and/or annihilation of cosmic...
متن کاملar X iv : a st ro - p h / 98 11 19 7 v 1 1 2 N ov 1 99 8 The ‘ bare ’ strange stars might not be bare
متن کامل
ar X iv : a st ro - p h / 98 11 41 8 v 1 2 6 N ov 1 99 8 Astrophysics on the GRAPE Family of Special Purpose Computers Piet Hut Institute for Advanced Study
The GRAPE-4, the world's fastest computer in 1995-1997, has produced some major scientific results, through a wide diversity of large-scale simulations in astrophysics. Applications have ranged from planetary formation, through the evolution of star clusters and galactic nuclei, to the formation of galaxies and clusters of galaxies.
متن کامل