Spin Signatures in Horizon-Resolved Images of LLAGN

Speaker

Dr. Daniel Palumbo, Harvard University

Abstract

With the advent of the Event Horizon Telescope (EHT), near-horizon black hole imaging with sub-mm very-long-baseline interferometry (VLBI) is now routine for the two sources for which terrestrial VLBI is sufficient to resolve the black hole shadow: Messier 87* and Sagittarius A*. Since the first images of M87*, the theoretical analysis of these images has advanced a broad class of black hole spin tracers in horizon-resolving observations, all of which have complex interplay with the astrophysical conditions near the horizon. Meanwhile, space VLBI mission concepts such as the Black Hole Explorer aim to drastically improve the angular resolution available via sub-mm VLBI, resolving out the primary accretion disk image to isolate the strongly lensed "photon ring," which more robustly exposes black hole mass, spin, and viewing inclination to distant observers. In this talk, I will detail the spin signatures in both of these angular resolution regimes, and how they work together to build a "robustness ladder" for spin measurement with which the spins of many more low-luminosity AGN will soon become accessible as sub-mm VLBI sensitivity, frequency coverage, angular resolution improves. The resulting local "spin census" will help fill in missing pieces of the history of accretion and merging in the broader AGN population.

Coupling Driven H2 Excitation in Seyferts: GATOS JWST/MRS

Speaker

Daniel Delaney, University of Alaska

Abstract 

We utilize James Webb Space Telescope/Mid Infrared Instrument (JWST/MIRI) Integral Field Unit observations from the Galaxy Activity, Torus and Outflow Survey to investigate the diverse range of ionized outflow rates of obscured active galactic nuclei (AGN) with similar bolometric luminosity and explore potential associations with AGN feedback. We explore spatial correlations between ionized emission potentially associated with fast shocks ([Fe II]5.34μm) and the excitation of H2. We further constrain our investigation to the inner 400 pc (the nuclear and circumnuclear regions r < 200 pc), and estimate the excitation temperature and column density of H2 assuming local thermodynamic equilibrium and using the S(1)–S(8) rotational H2 emission lines visible to JWST/MIRI spectroscopy. We report the molecular gas temperature of the deprojected 400 pc nuclear region to correlate with the ionized mass outflow rate. We also observe a stronger degree of spatial correlation between [Fe II]5.34μm emission and H2 gas temperature. We observe regions of enhanced [Fe II]5.34μm/[Ar II]6.99μm spatially coincident with the ionization cones of objects with higher ionized outflow rates and [Fe II]5.34μm/[Ar II]6.99μm in the deprojected 400 pc nuclear region to scale positively with both the ionized outflow rate and the estimated molecular gas temperature. We do not observe the estimated jet cavity power within the central 400 pc as strongly correlated with the ionized mass outflow rate or molecular gas temperature of the nuclear region. We take the preceding observations to suggest a higher degree of interaction between AGN outflows and the circumnuclear disk.

Seminar Connection

Zoom Registration (note this is a new registration link), you will receive connection details by email after registration: 

https://alaska.zoom.us/meeting/register/V1okit8uSk2ql97gegbdzg