102 citations · 465 across the 20 of their papers we have counts for
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Little Red Dots As Super-Eddington Fountain Flows
Nicholas Kaaz, Eliot Quataert, Taya Govreen-Segal +1
Little red dots (LRDs) may be powered by supermassive black holes (SMBHs) accreting above the Eddington limit. Spectroscopy of LRDs often shows absorption troughs blueshifted by $\…
Changing-Look AGN Powered By Disk Tearing
Nicholas Kaaz, Matthew Liska, Charlotte Ward +1
Changing-look active galactic nuclei (CLAGN) feature order-of-magnitude variability in both the continuum and broad line luminosities on months-to-years long timescales, and are cu…
H-AMR FORGE'd in FIRE I: Magnetic state transitions, jet launching and radiative emission in super-Eddington, highly magnetized quasar disks formed from cosmological initial conditions
Nicholas Kaaz, Matthew Liska, Alexander Tchekhovskoy +2
Quasars are powered by supermassive black hole (SMBH) accretion disks, yet standard disk models are inconsistent with many quasar observations. Recently, Hopkins et al. (2024) simu…
Extreme scale height variations and nozzle shocks in warped disks
Nicholas Kaaz, Yoram Lithwick, Matthew Liska +1
Accretion disks around both stellar-mass and supermassive black holes are likely often warped. Whenever a disk is warped, its scale height varies with azimuth. Sufficiently strong…
Misaligned magnetized accretion flows onto spinning black holes: Magneto-spin alignment, outflow power, and intermittent jets
Koushik Chatterjee, Nicholas Kaaz, Matthew Liska +2
Magnetic fields regulate black hole (BH) accretion, governing both inflow and outflow dynamics. When a BH accumulates substantial vertical magnetic flux, it enters the magnetically…
Winds and Disk Turbulence Exert Equal Torques on Thick Magnetically Arrested Disks
Vikram Manikantan, Nicholas Kaaz, Jonatan Jacquemin-Ide +4
The conventional accretion disk lore is that magnetized turbulence is the principal angular momentum transport process that drives accretion. However, when dynamically important la…
Magnetic flux plays an important role during a BHXRB outburst in radiative 2T GRMHD simulations
M. T. P. Liska, N. Kaaz, K. Chatterjee +2
Black hole (BH) X-ray binaries cycle through different spectral states of accretion over the course of months to years. Although fluctuations in the BH mass accretion rate are gene…
Radiation Transport Two-Temperature GRMHD Simulations of Warped Accretion Disks
M. T. P. Liska, N. Kaaz, G. Musoke +2
In many black hole systems, the accretion disk is expected to be misaligned with respect to the black hole spin axis. If the scale height of the disk is much smaller than the misal…
Nozzle Shocks, Disk Tearing and Streamers Drive Rapid Accretion in 3D GRMHD Simulations of Warped Thin Disks
Nicholas Kaaz, Matthew T. P. Liska, Jonatan Jacquemin-Ide +4
The angular momentum of gas feeding a black hole (BH) is typically misaligned with respect to the BH spin, resulting in a tilted accretion disk. Rotation of the BH drags the surrou…
Jetted and Turbulent Stellar Deaths: New LVK-Detectable Gravitational Wave Sources
Ore Gottlieb, Hiroki Nagakura, Alexander Tchekhovskoy +6
Upcoming LIGO/Virgo/KAGRA (LVK) observing runs are expected to detect a variety of inspiralling gravitational-wave (GW) events, that come from black-hole and neutron-star binary me…
Bridging Bondi and Event Horizon Scales: 3D GRMHD Simulations Reveal X-Shaped Radio Galaxy Morphology
Aretaios Lalakos, Ore Gottlieb, Nick Kaaz +6
X-shaped radio galaxies (XRGs) produce misaligned X-shaped jet pairs and make up of radio galaxies. XRGs are thought to emerge in galaxies featuring a binary superma…
Jet Formation in 3D GRMHD Simulations of Bondi-Hoyle-Lyttleton Accretion
Nicholas Kaaz, Ariadna Murguia-Berthier, Koushik Chatterjee +2
A black hole (BH) travelling through a uniform, gaseous medium is described by Bondi-Hoyle-Lyttleton (BHL) accretion. If the medium is magnetized, then the black hole can produce r…
The hydrodynamic evolution of binary black holes embedded within the vertically stratified disks of active galactic nuclei
Nicholas Kaaz, Sophie Lund Schrøder, Jeff J. Andrews +2
Stellar-mass black holes can become embedded within the gaseous disks of active galactic nuclei (AGNs). Afterwards, their interactions are mediated by their gaseous surroundings. I…
Illuminating black hole subsystems in young star clusters
Nicholas Kaaz, Kyle Kremer, Katie Auchettl +1
There is increasing evidence that globular clusters retain sizeable black hole populations at present day. This is supported by dynamical simulations of cluster evolution, which ha…
H-AMR: A New GPU-accelerated GRMHD Code for Exascale Computing With 3D Adaptive Mesh Refinement and Local Adaptive Time-stepping
M. T. P. Liska, K. Chatterjee, D. Issa +10
General-relativistic magnetohydrodynamic (GRMHD) simulations have revolutionized our understanding of black hole accretion. Here, we present a graphics processing unit (GPU) accele…
Bondi-Hoyle-Lyttleton Accretion onto Star Clusters
Nicholas Kaaz, Andrea Antoni, Enrico Ramirez-Ruiz
An isolated star moving supersonically through a uniform gas accretes material from its gravitationally-induced wake. The rate of accretion is set by the accretion radius of the st…
Lessons from HAWC PWNe observations: the diffusion constant is not a constant; Pulsars remain the likeliest sources of the anomalous positron fraction; Cosmic rays are trapped for long periods of time in pockets of inefficient diffusion
Stefano Profumo, Javier Reynoso-Cordova, Nicholas Kaaz +1
Recent TeV observations of nearby pulsars with the HAWC telescope have been interpreted as evidence that the diffusion of high-energy electrons and positrons within pulsar wind neb…