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GRRMHD Simulations of Tidal Disruption Event Accretion Disks around Supermassive Black Holes: Jet Formation, Spectra, and Detectability
Brandon Curd, Ramesh Narayan
We report results from general relativistic radiation MHD (GRRMHD) simulations of a super-Eddington black hole (BH) accretion disk formed as a result of a tidal disruption event (T…
Testing General Relativity with the Black Hole Shadow Size and Asymmetry of Sagittarius A*: Limitations from Interstellar Scattering
Ziyan Zhu, Michael D. Johnson, Ramesh Narayan
The Event Horizon Telescope (EHT), a global 230 GHz VLBI array, achieves an angular resolution of , sufficient to resolve the supermassive black hole Sagit…
Density jump as a function of magnetic field strength for parallel collisionless shocks in pair plasmas
Antoine Bret, Ramesh Narayan
Collisionless shocks follow the Rankine-Hugoniot jump conditions to a good approximation. However, for a shock propagating parallel to a magnetic field, magnetohydrodynamics states…
Fast radio burst source properties from polarization measurements
Wenbin Lu, Pawan Kumar, Ramesh Narayan
Recent polarization measurements of fast radio bursts (FRBs) provide new insights on these enigmatic sources. We show that the nearly 100% linear polarization and small variation o…
Two-temperature, Magnetically Arrested Disc simulations of the jet from the supermassive black hole in M87
Andrew Chael, Ramesh Narayan, Michael D. Johnson
We present two-temperature, radiative general relativistic magnetohydrodynamic simulations of Magnetically Arrested Discs (MAD) that launch powerful relativistic jets. The mass acc…
The Scattering and Intrinsic Structure of Sagittarius A* at Radio Wavelengths
Michael D. Johnson, Ramesh Narayan, Dimitrios Psaltis +12
Radio images of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), are dominated by interstellar scattering. Previous studies of Sgr A* have adopted an anisotrop…
Numerical evolution of shocks in the interior of Kerr black holes
Paul M. Chesler, Erik Curiel, Ramesh Narayan
We numerically solve Einstein's equations coupled to a scalar field in the interior of Kerr black holes. We find shock waves form near the inner horizon. The shocks grow exponentia…
Viewing angle of binary neutron star mergers
Hsin-Yu Chen, Salvatore Vitale, Ramesh Narayan
The joint detection of the gravitational wave (GW) GW170817 and its electromagnetic (EM) counterparts GRB170817A and kilonova AT 2017gfo has triggered extensive study of the EM emi…
Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole
G. Witzel, G. Martinez, J. Hora +16
Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the mo…
The role of electron heating physics in images and variability of the Galactic Centre black hole Sagittarius A*
Andrew Chael, Michael E. Rowan, Ramesh Narayan +2
The accretion flow around the Galactic Center black hole Sagittarius A* (Sgr A*) is expected to have an electron temperature that is distinct from the ion temperature, due to weak…
A Model for Anisotropic Interstellar Scattering and its Application to Sgr A*
Dimitrios Psaltis, Michael Johnson, Ramesh Narayan +3
Scattering in the ionized interstellar medium is commonly observed to be anisotropic, with theories of magnetohydrodynamic (MHD) turbulence explaining the anisotropy through a pref…
Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
Andrew A. Chael, Michael D. Johnson, Katherine L. Bouman +3
Interferometric imaging now achieves angular resolutions as fine as 10 microarcsec, probing scales that are inaccessible to single telescopes. Traditional synthesis imaging methods…
Shadows of spherically symmetric black holes and naked singularities
Rajibul Shaikh, Prashant Kocherlakota, Ramesh Narayan +1
We compare shadows cast by Schwarzschild black holes with those produced by two classes of naked singularities that result from gravitational collapse of spherically symmetric matt…