Narrow Results

We report on the results from the observations in very high energy band (VHE, E_γ ≥ 100 GeV) of the γ-ray binary LS I +61 303 and the black hole X-ray binary (BHXB) Cygnus X-1. LS I +61 303 was recently discovered at VHE by MAGIC¹ and here we present the preliminary results from an extensive observation campaign, comprising 112 observation hours covering 4 orbital cycles, aiming at determining the time-dependent features of the VHE emission. Cygnus X-1 was observed for a total of 40 hours during 26 nights, spanning the period between June and November 2006. We report on the results of the searches for steady and variable γ-ray signals from Cygnus X-1, including the first experimental evidence for an intense flare, of duration between 1.5 and 24 hours.

The BATSE instrument aboard the Compton Gamma Ray Observatory monitored numerous astronomical sources, including the Galactic black holes Cygnus X-1, GRO J0422+32, GRO J1719-24, GRS 1915+105, and GRO J1655-40, almost continuously from 1991 to 2000 in the energy range 23–1798 keV. We present results for these five black holes from the full nine-year BATSE earth occultation database using the JPL data analysis package EBOP (Enhanced BATSE Occultation Package). Light curves in four broad energy bands with 1-day resolution are presented showing flux histories for each source over the nine years. Spectra during the high flux/outburst states and low flux/quiescent states for these objects are also presented. The differences in the spectra suggest that there may two different classes of Galactic black holes.

PoGOLite is a balloon-borne soft gamma-ray (X-ray) polarimeter operating in the 25-80 keV energy band. The polarisation of incoming photons is determined using Compton scattering and photo-absorption events reconstructed in an array of plastic scintillator detector cells surrounded by a BGO side anticoincidence shield and a polyethylene neutron shield. Observations take place from a stratospheric balloon operating at an altitude of ∼40 km. A custom attitude control system keeps the polarimeter field-of-view aligned to targets of interest. The maiden ‘pathfinder’ flight of PoGOLite took place from the Esrange Space Centre in July 2011.