Speaker
Description
We studied gamma-ray emission from Cyg X-3 and Cyg X-1 with the LAT. With the currently improved calibration and background determination, we studied spectra and variability of Cyg X-3 in its soft, intermediate and hard states and during bright flares. We measured detailed spectra for all of the states except for finding upper limits only in the hard state, in spite of strong radio emission correlated with X-rays in that state. We also measured the orbital modulation to a much greater precision than before. We modelled the spectra and the modulation in terms of jet models and found strong constraints on the location of the bulk of the emission (at a distance along the jet comparable to the separation). The gamma-ray emission is strongly correlated with the radio, which allows us to measure the time lag.
In the case of Cyg X-1, we determined a detailed LAT spectrum in the hard/intermediate state and found a significant soft excess below 60 MeV. Also, while we found no soft-state emission above 100 MeV, we found a significant flux below it. In both cases, the soft excesses connect to the previously measured MeV tails.
