Bart Ripperda
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View article: Reconnection-driven Flares in M87*: Proton–Synchrotron-powered GeV Emission
Reconnection-driven Flares in M87*: Proton–Synchrotron-powered GeV Emission Open
Magnetic reconnection in current layers that form intermittently in radiatively inefficient accretion flows onto black holes is a promising mechanism for particle acceleration and high-energy emission. It has been recently proposed that su…
View article: Black Hole Collisions with Thin Accretion Disks: OJ 287 and Small Mass Ratio Supermassive Black Hole Binary Candidates
Black Hole Collisions with Thin Accretion Disks: OJ 287 and Small Mass Ratio Supermassive Black Hole Binary Candidates Open
OJ 287 is the best-known supermassive black hole binary candidate in the nanohertz gravitational-wave band. It exhibits periodic flares every ∼12 yr, likely caused by collisions of a lower-mass secondary with the accretion disk surrounding…
View article: Black Hole Collisions With Thin Accretion Disks: OJ 287 and Small-Mass-Ratio Supermassive Black Hole Binary Candidates
Black Hole Collisions With Thin Accretion Disks: OJ 287 and Small-Mass-Ratio Supermassive Black Hole Binary Candidates Open
OJ 287 is the best-known supermassive black hole binary candidate in the nanohertz gravitational wave band. It exhibits periodic flares every $\sim$ 12 years, likely caused by collisions of a smaller-mass secondary with the accretion disk …
View article: Compact stellar systems hosting an intermediate-mass black hole: Magnetohydrodynamic study of inflow-outflow dynamics
Compact stellar systems hosting an intermediate-mass black hole: Magnetohydrodynamic study of inflow-outflow dynamics Open
Context. Intermediate-mass black holes (IMBHs) have remained elusive in observations; there have been only a handful of tentative detections. One promising location for the existence of IMBHs is in dense stellar clusters such as IRS 13E in…
View article: Reconnection-driven Flares in M87*: Proton-Synchrotron-powered GeV Emission
Reconnection-driven Flares in M87*: Proton-Synchrotron-powered GeV Emission Open
Magnetic reconnection in current layers that form intermittently in radiatively inefficient accretion flows onto black holes is a promising mechanism for particle acceleration and high-energy emission. It has been recently proposed that su…
View article: On the Universality of the Split Monopole Black Hole Magnetosphere
On the Universality of the Split Monopole Black Hole Magnetosphere Open
Black holes (BHs) can acquire magnetic flux from their progenitor, through merger with a magnetized star, or via prolonged accretion. We study the evolution of BH magnetospheres using axisymmetric general relativistic magnetohydrodynamic s…
View article: Magnetized Accretion onto Neutron Stars: From Photon-trapped to Neutrino-cooled Flows
Magnetized Accretion onto Neutron Stars: From Photon-trapped to Neutrino-cooled Flows Open
When a neutron star (NS) intercepts gas from a nondegenerate star, e.g., in a tidal disruption event, a common-envelope phase, or the collapsing core of a massive star, photons become trapped in the hot flow around the NS. This gas forms a…
View article: Deep learning inference with the Event Horizon Telescope
Deep learning inference with the Event Horizon Telescope Open
Context . In a series of publications, we describe a comprehensive comparison of Event Horizon Telescope (EHT) data with theoretical models of the observed Sagittarius A* (Sgr A * ) and Messier 87* (M87 * ) horizon-scale sources. Aims . In…
View article: Universal Radial Scaling of Large-Scale Black Hole Accretion for Magnetically Arrested And Rocking Accretion Disks
Universal Radial Scaling of Large-Scale Black Hole Accretion for Magnetically Arrested And Rocking Accretion Disks Open
Accretion onto supermassive black holes (BHs) can launch relativistic jets that inject energy and momentum into their surroundings. Understanding how such feedback shapes large-scale accretion is key to bridging observations from galactic …
View article: Modeling of Lightcurves from Reconnection-powered Very High-energy Flares from M87*
Modeling of Lightcurves from Reconnection-powered Very High-energy Flares from M87* Open
The black hole at the center of M87 is observed to flare regularly in the very high-energy (VHE) band, with photon energies ≳100 GeV. The rapid variability, which can be as short as 2 days in the VHE lightcurve, constrains some of the flar…
View article: Magnetized Accretion onto Neutron Stars: from Photon-trapped to Neutrino-cooled Flows
Magnetized Accretion onto Neutron Stars: from Photon-trapped to Neutrino-cooled Flows Open
When a neutron star (NS) intercepts gas from a non-degenerate star, e.g., in a tidal disruption event, a common-envelope phase, or the collapsing core of a massive star, photons become trapped in the hot flow around the NS. This gas forms …
View article: Modeling of lightcurves from reconnection-powered very high energy flares from M87*
Modeling of lightcurves from reconnection-powered very high energy flares from M87* Open
The black hole at the center of M87 is observed to flare regularly in the very high energy (VHE) band, with photon energies $\gtrsim 100$ GeV. The rapid variability, which can be as short as $2$ days in the VHE lightcurve constrains some o…
View article: On the universality of the split monopole black hole magnetosphere
On the universality of the split monopole black hole magnetosphere Open
Black holes can acquire magnetic flux from their magnetized progenitor or via prolonged accretion. We study the evolution of black hole magnetospheres by means of axisymmetric general relativistic magnetohydrodynamic simulations. We show t…
View article: Black Hole Pulsars and Monster Shocks as Outcomes of Black Hole–Neutron Star Mergers
Black Hole Pulsars and Monster Shocks as Outcomes of Black Hole–Neutron Star Mergers Open
The merger of a black hole (BH) and a neutron star (NS) in most cases is expected to leave no material around the remnant BH; therefore, such events are often considered as sources of gravitational waves without electromagnetic counterpart…
View article: Comparison of magnetic diffusion and reconnection in ideal and resistive relativistic magnetohydrodynamics, ideal magnetodynamics, and resistive force-free electrodynamics
Comparison of magnetic diffusion and reconnection in ideal and resistive relativistic magnetohydrodynamics, ideal magnetodynamics, and resistive force-free electrodynamics Open
High-energy astrophysical systems and compact objects are frequently modeled using ideal relativistic magnetohydrodynamic (MHD) or force-free electrodynamic (FFE) simulations, with the underlying assumption that the discretisation from the…
View article: Two-temperature treatments in magnetically arrested disc GRMHD simulations more accurately predict light curves of Sagittarius A*
Two-temperature treatments in magnetically arrested disc GRMHD simulations more accurately predict light curves of Sagittarius A* Open
The Event Horizon Telescope Collaboration (EHTC) observed the Galactic centre source Sagittarius A$^\ast$ (Sgr A$^{\ast }$) and used emission models primarily based on single ion temperature (1T) general relativistic magnetohydrodynamic (G…
View article: Two-temperature treatments in magnetically arrested disk GRMHD simulations more accurately predict light curves of Sagittarius A*
Two-temperature treatments in magnetically arrested disk GRMHD simulations more accurately predict light curves of Sagittarius A* Open
Reproduction package for Salas, Liska, Markoff et al. 2025, MNRAS"Two-temperature treatments in magnetically arrested disk GRMHD simulations more accurately predict light curves of Sagittarius A*"Paper: https://doi.org/10.1093/mnras/staf24…
View article: Bulk Motions in the Black Hole Jet Sheath as a Candidate for the Comptonizing Corona
Bulk Motions in the Black Hole Jet Sheath as a Candidate for the Comptonizing Corona Open
Using two-dimensional general relativistic resistive magnetohydrodynamic simulations, we investigate the properties of the sheath separating the black hole jet from the surrounding medium. We find that the electromagnetic power flowing thr…
View article: Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes
Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes Open
Supermassive binary black holes in galactic centers are potential multimessenger sources in gravitational waves and electromagnetic radiation. To find such objects, isolating unique electromagnetic signatures of their accretion flow is key…
View article: First Mid-infrared Detection and Modeling of a Flare from Sgr A*
First Mid-infrared Detection and Modeling of a Flare from Sgr A* Open
The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. Ho…
View article: Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations
Effective Resistivity in Relativistic Reconnection: A Prescription Based on Fully Kinetic Simulations Open
A variety of high-energy astrophysical phenomena are powered by the release—via magnetic reconnection—of the energy stored in oppositely directed fields. Single-fluid resistive magnetohydrodynamic (MHD) simulations with uniform resistivity…
View article: Effective resistivity in relativistic reconnection: a prescription based on fully kinetic simulations
Effective resistivity in relativistic reconnection: a prescription based on fully kinetic simulations Open
A variety of high-energy astrophysical phenomena are powered by the release -- via magnetic reconnection -- of the energy stored in oppositely directed fields. Single-fluid resistive magnetohydrodynamic (MHD) simulations with uniform resis…
View article: Visualizing black holes and wormholes through raytracing
Visualizing black holes and wormholes through raytracing Open
We explored the visualization of black holes and wormholes using code and ray-tracing programs. We introduced an advancement in astrophysics with the creation of a 4-color screen of a traversable Morris-Thorne wormhole, achieved through th…
View article: Black hole pulsars and monster shocks as outcomes of black hole--neutron star mergers
Black hole pulsars and monster shocks as outcomes of black hole--neutron star mergers Open
The merger of a black hole (BH) and a neutron star (NS) in most cases is expected to leave no material around the remnant BH; therefore, such events are often considered as sources of gravitational waves without electromagnetic counterpart…
View article: Bulk Motions in the Black Hole Jet Sheath as a Candidate for the Comptonizing Corona
Bulk Motions in the Black Hole Jet Sheath as a Candidate for the Comptonizing Corona Open
Using two-dimensional general relativistic resistive magnetohydrodynamic simulations, we investigate the properties of the sheath separating the black hole jet from the surrounding medium. We find that the electromagnetic power flowing thr…
View article: A New Particle Pusher with Hadronic Interactions for Modeling Multimessenger Emission from Compact Objects
A New Particle Pusher with Hadronic Interactions for Modeling Multimessenger Emission from Compact Objects Open
We propose novel numerical schemes based on the Boris method in curved spacetime, incorporating both hadronic and radiative interactions for the first time. Once the proton has lost significant energy due to radiative and hadronic losses, …
View article: Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes
Dual Jet Interaction, Magnetically Arrested Flows, and Flares in Accreting Binary Black Holes Open
Supermassive binary black holes in galactic centers are potential multimessenger sources in gravitational waves and electromagnetic radiation. To find such objects, isolating unique electromagnetic signatures of their accretion flow is key…
View article: Monster Shocks, Gamma-Ray Bursts, and Black Hole Quasi-normal Modes from Neutron-star Collapse
Monster Shocks, Gamma-Ray Bursts, and Black Hole Quasi-normal Modes from Neutron-star Collapse Open
We perform the first magnetohydrodynamic simulation tracking the magnetosphere of a collapsing magnetar. The collapse is expected for massive rotating magnetars formed in merger events and may occur many hours after the merger. Our simulat…
View article: Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode
Broadband multi-wavelength properties of M87 during the 2018 EHT campaign including a very high energy flaring episode Open
Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (M…