Search Publications
The radial distribution of galactic gamma rays. IV. The whole galaxy.
Strong, A. W.; Grenier, I. A.; Hermsen, W. +6 more
The correlation between diffuse galactic γ-rays and gas tracers is studied using the final COS-B database and H I and CO surveys covering the entire galactic plane. A good quantitative fit to the γ-rays is obtained, with a small gradient in the γ-ray emissivity per hydrogen atom. The average ratio of H2 column density to integrated CO t…
High energy gamma rays from the VELA pulsar : long-term variability and energy distribution.
Grenier, I. A.; Hermsen, W.; Clear, J.
New results on the temporal and spectral characteristics of the high energy (50 MeV to 5 GeV) gamma ray emission from the Vela pulsar are presented. A new sensitive analysis method using maximum likelihood techniques has been applied to the final COS-B dataset. The whole pulsed flux is found to exhibit long term variability. The energy spectrum of…
High-energy gamma rays as a probe of cosmic-ray spectral differences throughout the Galaxy. II - A comparison with radio synchrotron emission
Schlickeiser, R.; Bloemen, J. B. G. M.; Reich, W. +1 more
A spectral analysis of the galactic high-energy γ-ray emission (300 MeV-6 GeV) is presented using the observations obtained with the COS-B satellite. Large-scale spectral variations are found and compared with recent results from a study of the galatic radio-continuum emission at 408 and 1420 MHz. The combination of the radio and γ-ray findings es…
On the High-Energy Gamma-Ray Signature of Cosmic-Ray Sources
Ormes, J. F.; Ozel, M. E.; Morris, D. J.
If cosmic rays are accelerated by strong shocks, then cosmic-ray sources should be characterized by spectra, dN/dE is proportional to p^-(2.0-2.2)^, reflecting the strength of those shocks. This is expected from the "standard leaky box" model of cosmic-ray propagation in which the source spectra are harder than the observed spectra because higher …
High resolution cluster method for topological studies of the light curves of gamma-ray pulsars.
Buccheri, R.; Sacco, B.; di Gesu, V. +1 more
The authors describe a non-parametric, binning-free, adaptive method for the detection and the analysis of structures in the light curves of gamma-ray pulsars, based on a clustering technique. They use computer simulated data and a sample of COS-B data relative to the Vela pulsar to show its behavior and robustness. As a main result they find that…
Search for Linear Polarization in Gamma-Ray Sources: Possible Evidence for the VELA Pulsar
Caraveo, P. A.; Bignami, G. F.; Mitrofanov, I. +1 more
The use of the azimuthal distribution of planes containing e(+)/e(-) pairs from high-energy photon materialization to investigate the nature of gamma-ray sources is discussed. Analytical work done on COS B data for bright COS B sources (Vela, Crab, and Geminga) and for a reference background region is presented along with results which are indicat…
Periodicity Search in Sources with Low Count Rate
Bisnovatyi-Kogan, G. S.; Gurin, L. S.; Beliaeva, N. P. +2 more
The problem of discovery and estimation of the period, slowly changing in time is considered, when the pulses are rare. Several criteria are proposed on the base of which a multilevel algorithm of the period detection is constructed. The reliability and precision of the period determination are investigated with taking into account of the correlat…
Two new results on PSR 0833-45: (1) optical data on its birthplace, and (2) possible polarization in its high energy gamma-ray emission
Bignami, G. F.
Two new and completely different results are presented, both related to the Vela pulsar PSR 0833-45. In Part I, recent ESO optical images of the pulsar and its starfield are compared to the discovery plates, and used to set stringent upper limits on its proper motion and thus on its birthplace. Consequences are briefly explored. Part 2 refers to a…