Black Holes and Accretion: Observational Frontiers X-ray Spectra of Active Galactic Nuclei: Inner Disc or an Obscuring Veil? Black Holes and Accretion: Observational Frontiers Dom Walton NASA Postdoctoral Fellow JPL/Caltech Hi! Its my pleasure to be here to tell you about my work on the observational side of BH research. Dom Walton H51

Black Holes and Spin Fully defined by: Mass, M Spin, a (angular momentum , -1 < a < 1) Cygnus A (radio) Relativistic Jets: Powered by black hole spin? Quick fact about black holes, they’re fully defined by mass and spin (angular momentum) One other cool thing we know some black holes do is launch relativistic jets. We don’t really know how these are launched, but one popular idea is that they’re powered by BH spin. Can use the same tools to study both problems! Host galaxy scale Walton 4

Many minor accretion events Supermassive Black Hole Growth Major accretion events High Spin Supermassive black hole spin is of particular importance, as the SMBH spin distribution carries rare information about their growth history Major mergers -> spin up, minor mergers -> spin down. The current sample of 20 SMBH spin measurements is not yet sufficient to probe the intrinsic spin distribution; expanding this sample is one of the main goals I have for this fellowship. Used to test things like cosmological galaxy formation simulations Many minor accretion events Low Spin

Innermost Stable Circular Orbit BH spin Relativistic Disc Reflection Fe Kα (= X-rays) Explain physics of line broadening Broader the line, the higher the spin! Innermost Stable Circular Orbit BH spin Walton 7

Relativistic Iron Lines NGC3783 Occasionally you get supermassive black holes with clean spectra, but more typically you have absorption by intervening material. NGC1365 is one such example, and changes in this absorption lead to wild changes in the X-ray spectrum at ~2 keV With broadband X-ray coverage you can accurately model this out, and still robustly measure BH spin MCG-6-30-15 NGC1365

A Partially-Ionised Veil? Talk about reflection vs absorption degeneracy here

A Partially-Ionised Veil? Talk about reflection vs absorption degeneracy here

Relativisic disc reflection? Complex, partially-ionised absorption? The Essay Relativisic disc reflection? Complex, partially-ionised absorption? The aim for this essay is to consider and compare the observational evidence for each of these interpretations for the broad iron features observed in the X-ray spectra of AGN Explain physics of line broadening Broader the line, the higher the spin!