Written by Michael Allen
A team of international astronomers has made a significant breakthrough regarding supermassive black holes using NASA’s IXPE (Imaging X-ray Polarimetry Explorer). They pinpointed the source of X-rays in a black hole’s jet, finally answering a question that has puzzled scientists for decades. Their research features in a recent paper in The Astrophysical Journal Letters.
The IXPE mission focused on the Perseus Cluster, the brightest galaxy cluster visible in X-rays, over more than 600 hours between January and March. This marks not just the longest observation for IXPE, but also its debut in studying a galaxy cluster.
The scientists turned their attention to 3C 84, a well-known active galaxy at the center of the Perseus Cluster. This galaxy is frequently observed due to its brightness and proximity.
The Perseus Cluster is vast, containing a massive amount of X-ray emitting gas, heated to core-like temperatures. IXPE’s ability to combine data with NASA’s Chandra X-ray Observatory and other missions was crucial for deciphering incoming signals.
- IXPE’s polarization measurements reveal how X-ray light waves are aligned. High levels of synchronization mean greater polarization.
- X-rays from 3C 84 likely arise from inverse Compton scattering, where light interacts with particles, gaining energy. IXPE’s data helps discern this process from others.
- The term “seed photons” refers to the lower-energy radiation involved in inverse Compton scattering.
- Fans of astronomy may recognize the Perseus Cluster from a sonification that mimicked its black hole’s sounds in May 2022.
“While measuring the polarization of 3C 84 was key, we are still looking for other signals that might indicate more exotic physics,” said Steven Ehlert, project scientist for IXPE.
Ioannis Liodakis, a leading researcher on the study, confirmed, “We’ve established that in cases like 3C 84, the X-rays come from inverse Compton scattering. IXPE gave us a rare opportunity to examine seed photons in detail.”
The first scenario for these photons is synchrotron self-Compton, where radiation originates within the same jet producing the energetic particles. In contrast, the external Compton scenario suggests these photons come from external sources.
“The two scenarios predict different X-ray polarization outcomes,” noted Frederic Marin, a co-author of the study. “If we detect X-ray polarization in 3C 84, it virtually rules out external Compton as the emission mechanism.”
Throughout their 60-day campaign, optical and radio telescopes closely monitored 3C 84 to test these theories.
IXPE recorded a net polarization of 4% in its X-ray spectrum, with similar results from optical and radio data. These findings strongly support the synchrotron self-Compton model, suggesting that the seed photons come from the jet itself.
“Separating these components was crucial and couldn’t be achieved with just one X-ray telescope. We confirmed the polarization measurements specifically linked to 3C 84 by combining IXPE’s data with results from Chandra, NuSTAR, and Swift,” said Sudip Chakraborty, a co-author of the paper.
Looking ahead, scientists plan to analyze IXPE’s data from various locations within the Perseus Cluster for further insights.
NASA’s IXPE, a joint effort with the Italian Space Agency and collaborators from 12 countries, continues to provide valuable data for groundbreaking discoveries in astrophysics. The mission is led by NASA’s Marshall Space Flight Center.
For more details on IXPE’s mission, visit NASA’s IXPE page.
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Astrophysics, Chandra X-Ray Observatory, Galaxies, Galaxy clusters, IXPE (Imaging X-ray Polarimetry Explorer), Marshall Astrophysics, Marshall Science Projects, Marshall Science Research & Projects, Marshall Space Flight Center, The Universe, X-ray Astronomy
