11 papers
A Convolutional Neural Network for the Recovery of Transfer Functions From Velocity-Resolved Reverberation Mapping Data
Kirk Long, Keith Horne, Jason Dexter +1
One of the hallmarks of active galactic nuclei are that they are highly variable with time. In watching the spectra vary it has been observed that the emission-lines often appear t…
Electron-positron Pair Production in Global GRMHD Simulations of Black Hole Accretion Flows
Ho-Sang Chan, Jason Dexter, Mitchell C. Begelman
We present global, three-dimensional general relativistic magnetohydrodynamic simulations of accreting black holes that incorporate pair physics. Pairs are modeled as a passive sca…
Hot, Retrograde Tilted MADs: Misaligned, Precessing, and Shaped by Electromagnetic Torques
Sajal Gupta, Jason Dexter
Tilted accretion disks in the magnetically arrested (MAD) state may be present in X-ray binaries and active galactic nuclei such as Sgr A* and M87. We have carried out 3D global GR…
Little Red Dots As Late-stage Quasi-stars
Mitchell C. Begelman, Jason Dexter
We argue that the "Little Red Dots" (LRDs) discovered with the James Webb Space Telescope are quasi-stars in their late stages of evolution. Quasi-stars are hypothetical objects pr…
Demystifying flux eruptions: Magnetic flux transport in magnetically arrested disks
Jonatan Jacquemin-Ide, Mitchell C. Begelman, Beverly Lowell +3
Magnetically arrested disks (MADs) are a compelling model for explaining variability in low-luminosity active galactic nuclei (AGN), including horizon-scale outbursts like those ob…
The inner structure and thermodynamics of a thin accretion disc
A. Hankla, J. Dexter, N. Scepi
Using three-dimensional general relativistic magnetohydrodynamic simulations with electron and proton thermodynamics and an electron cooling function, we probe the inner radial and…