Search Publications
Second COS-B catalogue of high-energy gamma-ray sources.
Bignami, G. F.; Hermsen, W.; Masnou, J. L. +11 more
A list of 25 high-energy (greater than 100 MeV) gamma-ray sources detected by COS B is presented. Only four sources are identified with well-known objects. Of the remaining sources, 20 are at low galactic latitude, and they may represent a new galactic population. Their luminosity is estimated to be in the range of (0.4-5) x 10 to the 36th ergs/se…
3C 273 revisited : confirmation by COS-B of high energy gamma-ray emission.
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +11 more
The results of a second observation in the Virgo region by the ESA COS-B satellite are presented. The presence of a high- energy (50-800 MeV) gamma-radiation source is confirmed, and its position is consistent with 3C273. The error box at the 90% confidence level containing the quasar is ∼2.5 square degrees, and the probability of a chance coincid…
Search for gamma-radiation from extragalactic objects using a likelihood method.
Bignami, G. F.; Hermsen, W.; Masnou, J. L. +5 more
A search through COS-B data for gamma-radiation from a number of extragalactic objects reveals no strong evidence for any positive identification except, as already reported, for the region around the quasar 3C273. Upper limits to the photon fluxes from active extragalactic objects are evaluated using a likelihood method. They reinforce the conclu…
A change in light curve asymmetry and the ephemeris of CYG X-3.
van der Klis, M.; Bonnet-Bidaud, J. M.
Cygnus X-3 was observed in the 2-12 keV range for 40 days in May-June 1980. The mean 4.8 h light curve was seen to change significantly in a way suggestive of the existence of an underlying binary with an eclipse duration of 40 percent of the period. The observed time of X-ray minimum was found to increase the level of confidence of a period deriv…
The X-ray modulation of CYG X-3.
van der Klis, M.; Bonnet-Bidaud, J. M.
Results of three 40d COS-B X-rays observations of Cyg X-3 are presented. The shape of the light curve, although variable from cycle to cycle, is generally very stable when averaged over many cycles. During one four-week period, however, a different mean light curve was observed. It is shown that the correlated behavior of amplitude, average level,…
Long term X-ray observations of SMC X-1 including a turn-on.
van der Klis, M.; Bonnet-Bidaud, J. M.
A 38 d COS-B observation of SMC X-1 in the 2-12 keV band is presented, the observation including a turn-on of this source. The data are analyzed within the framework of the stellar wind accretion model, both from the point of view of the expected accretion rate and of the absorption of X-rays in the wind. It is noted that neither the high state lu…
The γ -ray Emissivity of the Local Interstellar Medium from Correlations with Gas at Intermediate Latitudes
Strong, A. W.; Wolfendale, A. W.
A survey of recent studies of the correlation between γ -rays from latitudes |b| > 10 degrees and gas tracers is presented. Results for the ranges 35-100 MeV and above 100 MeV from the SAS-2 satellite, and for energies between 70 and 5000 MeV from the COS-B satellite, are used to obtain an estimate of the γ -ray emissivity spectrum for all form…
Further COS-B evidence for gamma-ray emission from 3C273
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +7 more
The results of a third observation of the Virgo region of the sky by the ESA gamma-ray satellite COS-B are reported. The gamma-ray source (CG291 plus 65) was again seen, and the combined data are analyzed to improve on the position and time-averaged energy spectrum of the source. During the observation, the number of photons from the instrumental …
Galactic γ and radio synchrotron radiation
Osborne, J. L.; Phillipps, S.; Haslam, C. G. T. +2 more
The galactic γ-radiation and radio synchrotron radiation contains information on the distribution of cosmic-ray particles, magnetic field and gas throughout the Galaxy. We report here a new all-sky survey of 408-MHz radio continuum which has been used to compare the distributions of radio and γ-ray emission, with the former convolved to the respon…
Observation by COS-B of the gamma-ray source 2CG195/plus/04
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +7 more
Data accumulated from observations of the high-energy gamma-ray source 2CG195(plus)04 are used to improve the position and energy spectrum of the source, and to search for short term variability. Skymaps from four observations in three energy ranges are analyzed using the cross-correlation method by Hermsen (1980), and results are within the error…