Fine structure in the gamma-ray sky and the origin of UHECR

The EGRET results for gamma ray intensities in and near the Galactic Plane have been analysed in some detail. Attention has been concentrated on energies above 1 GeV and the individual intensities in a $4^{\circ}$ longitude bin have been determined and compared with the large scale mean found from a nine-degree polynomial fit. Comparison has been made of the observed standard deviation for the ratio of these intensities with that expected from variants of our model. The basic model adopts cosmic ray origin from supernova remnants, the particles then diffusing through the Galaxy with our usual `anomalous diffusion'. The variants involve the clustering of SN, a frequency distribution for supernova explosion energies, and 'normal', rather than 'anomalous' diffusion. It is found that for supernovae of unique energy, and our usual anomalous diffusion, clustering is necessary, particularly in the Inner Galaxy. An alternative, and preferred, situation is to adopt the model with a frequency distribution of supernova energies. The results for the Outer Galaxy are such that no clustering is required. If their explosion energies are distributed then supernovae can be the origin of UHECR.Comment: 8 pages, 5 figures and 1 table, to appear in the proceedings of the CRIS2006 symposium, Catania, Italy, May-June 200

Fine structure in the gamma-ray sky

The EGRET results for gamma-ray intensities in and near the Galactic Plane have been analysed in some detail. Attention has been concentrated on energies above 1 GeV and the individual intensities in a $4^\circ$ longitude bin have been determined and compared with the large scale mean found from a nine-degree polynomial fit. Comparison has been made of the observed standard deviation for the ratio of these intensities with that expected from variants of our model. The basic model adopts cosmic ray origin from supernova remnants, the particles then diffusing through the Galaxy with our usual 'anomalous diffusion'. The variants involve the clustering of SN, a frequency distribution for supernova explosion energies, and 'normal', rather than 'anomalous' diffusion. It is found that for supernovae of unique energy, and our usual anomalous diffusion, clustering is necessary, particularly in the Inner Galaxy. An alternative, and preferred, situation is to adopt the model with a frequency distribution of supernova energies. The results for the Outer Galaxy are such that no clustering is required.Comment: 10 pages, 4 figures, 1 table, accepted for publication in J.Phys.G: Nucl.Part.Phy

The diffuse GeV-TeV γ\gamma-ray emission of the Cygnus region

Recently the Milagro experiment observed diffuse multi-TeV gamma-ray emission in the Cygnus region, which is significantly stronger than what predicted by the Galactic cosmic ray model. However, the sub-GeV observation by EGRET shows no excess to the prediction based on the same model. This TeV excess implies possible high energy cosmic rays populated in the region with harder spectrum than that observed on the Earth. In the work we studied this theoretical speculation in detail. We find that, a diffuse proton source with power index $\alpha_p\lesssim 2.3$, or a diffuse electron source with power index $\alpha_e\lesssim2.6$ can reproduce the Milagro's observation without conflicting with the EGRET data. Further detections on neutrinos, a diagnostic of the hadronic model, and hard X-ray synchrontron radiation, a diagnostic of the lepton model, help to break this degeneracy. In combination with the gamma ray observations to several hundred GeV by Fermi, we will be able to understand the diffuse emission mechanisms in the Cygnus region better.Comment: 14 pages (aastex), 5 figures, accepted for publication by The Astrophysical Journa

Galactic diffuse gamma rays --- recalculation based on the new measurements of cosmic electron spectrum

In this work, we revisit the all-sky Galactic diffuse $\gamma$-ray emission taking into account the new measurements of cosmic ray electron/positron spectrum by PAMELA, ATIC and Fermi, which show excesses of cosmic electrons/positrons beyond the expected fluxes in the conventional model. Since the origins of the extra electrons/positrons are not clear, we consider three different scenarios to account for the excesses: the astrophysical sources such as the Galactic pulsars, dark matter decay and annihilation. Further, new results from Fermi-LAT of the (extra-)Galactic diffuse $\gamma$-ray are adopted. The background cosmic rays without the new sources give lower diffuse $\gamma$ rays compared to Fermi-LAT observation, which is consistent with previous analysis. The scenario with astrophysical sources predicts diffuse $\gamma$-rays with little difference with the background. The dark matter annihilation models with $\tau^{\pm}$ final state are disfavored by the Fermi diffuse $\gamma$-ray data, while there are only few constraints on the decaying dark matter scenario. Furthermore, these is always a bump at higher energies ($\sim$ TeV) of the diffuse $\gamma$-ray spectra for the dark matter scenarios due to final state radiation. Finally we find that the Fermi-LAT diffuse $\gamma$-ray data can be explained by simply enlarging the normalization of the electron spectrum without introduce any new sources, which may indicate that the current constraints on the dark matter models can be much stronger given a precise background estimate.Comment: 23pages,7figures; Fermi diffuse gamma ray data are used, the corresponding discussion and figs are changed, sections are reorganized and a new section is added. ApJ in pres

Diffuse continuum gamma rays from the Galaxy

A new study of the diffuse Galactic gamma-ray continuum radiation is presented, using a cosmic-ray propagation model which includes nucleons, antiprotons, electrons, positrons, and synchrotron radiation. Our treatment of the inverse Compton (IC) scattering includes the effect of anisotropic scattering in the Galactic interstellar radiation field (ISRF) and a new evaluation of the ISRF itself. Models based on locally measured electron and nucleon spectra and synchrotron constraints are consistent with gamma-ray measurements in the 30-500 MeV range, but outside this range excesses are apparent. A harder nucleon spectrum is considered but fitting to gamma rays causes it to violate limits from positrons and antiprotons. A harder interstellar electron spectrum allows the gamma-ray spectrum to be fitted above 1 GeV as well, and this can be further improved when combined with a modified nucleon spectrum which still respects the limits imposed by antiprotons and positrons. A large electron/IC halo is proposed which reproduces well the high-latitude variation of gamma-ray emission. The halo contribution of Galactic emission to the high-latitude gamma-ray intensity is large, with implications for the study of the diffuse extragalactic component and signatures of dark matter. The constraints provided by the radio synchrotron spectral index do not allow all of the <30 MeV gamma-ray emission to be explained in terms of a steep electron spectrum unless this takes the form of a sharp upturn below 200 MeV. This leads us to prefer a source population as the origin of the excess low-energy gamma rays.Comment: Final version accepted for publication in The Astrophysical Journal (vol. 537, July 10, 2000 issue); Many Updates; 20 pages including 49 ps-figures, uses emulateapj.sty. More details can be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm

"Cały ten nieład" : od Szymborskiej do Kochanowskiego

Toczący się nieustannie w obrębie literatury dialog jest jedną z magicznych jej właściwości. Wsłuchani weń badacze literatury - znawcy intertekstualności wyodrębniają, klasyfikują i nazywają różne jego rejestry, tracąc jednak przy tym bezpowrotnie ową magiczność. Czy znajdzie się bowiem dla niej miejsce pomiędzy alegorezą a archetypezą, restytucją emblematyczną a restytucją tematyczną, paratekstualnością a hipertekstualnością? Nie ujmując wysiłkom (i ich efektom) teoretyków intertekstualistów, uprawomocnionych wszak do tego typu działań z racji swej profesji, należy jednak nieustannie upominać się o rozumienie literatury jako świadectwa i przestrzeni spotkania. Skąd bowiem, jak nie z tekstów literackich, pochodzi wiedza o myślach i pragnieniach człowieka renesansu czy baroku? Jego „głos” można usłyszeć tylko dzięki literaturze i tylko dzięki niej można udzielić nań odpowiedzi. Krytyka oświeceniowego czy romantycznego światopoglądu ma sens jedynie w obrębie literatury - dzięki niej przeszłość nie zamyka się definitywnie, lecz paradoksalnie trwa, reinterpretowana w kontekście współczesności. Gdzie, jak nie w tekście literackim, może i powinna odbywać się polemika ze średniowieczną koncepcją istnienia? To za sprawą literatury mogą wziąć w niej udział wszyscy, nie tylko historycy badacze XIII czy XIV stulecia. [fragm. tekstu