NASA’s IXPE solves long-standing black hole jets mystery

The Perseus Cluster is the brightest galaxy cluster observable in X-rays. This IXPE mission focused on this galaxy cluster to discover where the X-rays in a supermassive black hole’s jet really came from. This is the first time IXPE observed a galaxy cluster. It is also IXPE’s longest observation of a single target since its launch.

In the Perseus Cluster’s center, there is an active galaxy called 3C 84. This galaxy is a common target for X-ray studies due to its proximity and brightness. This mission measured the polarization of 3C 84. The polarization measurements carry information about the orientation and alignment of emitted X-rays.

Scientists already believe that X-rays from active galaxies like 3C 84 result from inverse Compton scattering. Inverse Compton scattering is a process where low-energy photons are boosted to higher energy ranges, such as the X-ray range. This process happens by photon–electron scattering. The low-energy photons in this case are called seed photons. From this study, scientists came up with two scenarios for the origin of these seed photons.

The first scenario is the Synchrotron self-Compton, where the seed photons originate from the same jet that produces the higher-energy radiation. The other scenario suggests that the seed photons originate from background radiation outside the jet. This is called external Compton. The astronomers analyzed the available data and came to the conclusion that the Synchrotron self-Compton scenario was the more likely case for 3C 84.

To get these results, the astronomers combined IXPE’s observation with data from the Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR), and Neil Gehrels Swift Observatory. The findings from the study were published in the Astrophysical Journal Letters.