THE DEEP LOOK AT THE HARD X-RAY SKY: THE<i>SWIFT</i>โ<i>INTEGRAL</i>X-RAY (SIX) SURVEY
THE DEEP LOOK AT THE HARD X-RAY SKY: THE<i>SWIFT</i>โ<i>INTEGRAL</i>X-RAY (SIX) SURVEY
The supermassive black holes at the center of active galactic nuclei (AGNs) are surrounded by obscuring matter that can block nuclear radiation. Depending on the amount of blocked radiation, the flux from the AGN can be too faint to be detected by currently flying hard X-ray (above 15 keV) missions. โฆ