Chandra Imaging of the Outer Accretion Flow onto the Black Hole at the Center of the Perseus Cluster

TL;DR

This study uses advanced Chandra imaging techniques to constrain the size of the Fe K-alpha emission region in NGC 1275, revealing an extended structure consistent with a molecular torus fueling the black hole, and correlates X-ray flux dips with jet activity.

Contribution

The paper presents a novel high-resolution imaging approach to measure the accretion region size in NGC 1275, providing new insights into the structure fueling the black hole in Perseus.

Findings

Fe K-alpha emission region is less than 98 pc in size.

The emission region is consistent with an extended molecular torus or disk.

X-ray flux dips correlate with radio flaring and high GeV fluxes.

Abstract

Nowhere is black hole feedback seen in sharper relief than in the Perseus cluster of galaxies. Owing to a combination of astrophysical and instrumental challenges, however, it can be difficult to study the black hole accretion that powers feedback into clusters of galaxies. Recent observations with Hitomi have resolved the narrow Fe K-alpha line associated with accretion onto the black hole in NGC 1275 (3C 84), the active galaxy at the center of Perseus. The width of that line indicates the fluorescing material is located 6-45 pc from the black hole. Here, we report on a specialized Chandra imaging observation of NGC 1275 that offers a complementary angle. Using a sub-array, sub-pixel event repositioning, and an X-ray "lucky imaging" technique, Chandra imaging suggests an upper limit of about 0.3 arc seconds on the size of the Fe K-alpha emission region, corresponding to 98 pc. Both spectroscopy and direct imaging now point to an emission region consistent with an extended molecular torus or disk, potentially available to fuel the black hole. A low X-ray continuum flux was likely measured from NGC 1275; contemporaneously, radio flaring and record-high GeV fluxes were measured. This may be an example of the correlation between X-ray flux dips and jet activity that is observed in other classes of accreting black holes across the mass scale.