Abstract: The European Space Observatory INTEGRAL has been providing excellent results on X-ray and ?-ray astronomy since its launch in 2002. Among the most important results are the spectroscopy and imaging measurements of celestial ?-ray sources, including mapping the 511 keV radiation from the Galactic plane. However, the nature of the 511 keV positron annihilation line around the Galactic Center region is still a mystery. Similarly, the structure and nature of the Galactic Center supermassive black...

Source: New Mission Concept: Investigation ... the Galactic Center Explorer (GalCenEx)