Probing the inner regions of supermassive black hole accretion disks and jets
Keck, Mason Lawrence
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Active galactic nuclei (AGN), which host actively accreting supermassive black holes (SMBHs), present multiple mysteries. Primary among these are the physics of inner accretion disks and the production of relativistic plasma jets. Observations of two types of AGN, Seyfert galaxies and blazars, provide some of the most revealing clues toward solving these mysteries. I examine the inner accretion flow of Seyfert galaxies within ~10 Schwarzschild radii of the SMBH and the jet and its environment of blazars within ~10,000 Schwarzschild radii of the SMBH based on their X-ray, optical, and radio emission. Through measuring the relativistic distortion of the X-ray emission from the inner accretion disk, important properties of the inner accretion disk and black hole can be determined, including the black hole spin. I present a measurement of the spin of the SMBH at the center of the Seyfert Galaxy NGC 4151 through X-ray spectroscopy with the NuSTAR and Suzaku X-ray observatories, showing that it has a near-maximal value. Through probing blazar jets on parsec (pc) scales with high-resolution Very Long Baseline Array (VLBA) observations, fundamental details of AGN jets can be determined. I present a multi-frequency study of ten blazar jets to probe the jet shape and magnetic field on pc scales with the VLBA. I show that the jet of 3C 273 is consistent with being conical with adiabatic lateral expansion on ~pc scales. From estimating the SMBH masses in these sources with observations of emission lines with the Discovery Channel Telescope, I show that the regions probed with the VLBA are at a distance comparable to the Bondi radius. I discuss my results on the Seyfert galaxy NGC 4151 relative to the SMBH spin census. I compare NGC 4151 with a blazar, 3C 273, to put my results in broader context of AGN. I discuss the future of these studies with high spectral resolution X-ray missions such as Athena and with high frequency, higher angular resolution interferometric arrays such as the Event Horizon Telescope.
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