INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) is an ESA mission in cooperation with Russia and USA and was launched on 17 October 2002. It is the most sensitive gamma-ray observatory and its main task is to gather some of the most energetic radiation that comes from space. Gamma rays are even more powerful than the X-rays used in medical examinations. Earth’s atmosphere protects us from this dangerous radiation; therefore gamma-rays can only be detected with space telescopes. The satellite is 5 meters high, more than 4 tonnes in weight and orbits the Earth once every three days at an altitude higher than 40,000 Km. Equipped with four scientific instruments, it can detect Gamma rays from supernova explosions and study compact objects as neutron stars or black holes. It will also try to solve the mystery of flashes of extremely powerful radiation that suddenly appear somewhere in the gamma sky and disappear again after a short time.
Using the IBIS telescope onboard the INTEGRAL observatory, a team of astronomers led by I. Mereminskiy, analyzed the deepest observations from 12 years of data (2003-2015) from 3 deep extragalactic fields (M81, LMC, 3C 273/Coma) to detect 147 sources. Most of the sources have an extragalactic origin, including 37 observed in hard X-rays for the first time, expanding our knowledge about populations of extragalactic hard X-ray sources. The sample contains 98 AGN (64 Seyfert galaxies, 7 LINERs 3 XBONGs (X-ray Bright Optically Inactive Galaxies), 16 blazars and 8 AGN of unclear optical class), 2 galaxy clusters, 17 X-ray binaries and pulsars located in the Large and Small Magellanic Clouds, 3 Galactic cataclysmic variables and one Ultraluminous X-ray source, among others. 25 sources have not been identified.
Publication: Mereminskiy et al. 2016