Publications (51)
Plasmoid Instability in Forming Current Sheets
Luca Comisso, Manasvi Lingam, Yi-Min Huang +1
The plasmoid instability has revolutionized our understanding of magnetic reconnection in astrophysical environments. By preventing the formation of highly elongated reconnection l…
Generalized Magnetofluid Connections in Pair Plasmas
Felipe A. Asenjo, Luca Comisso, Swadesh M. Mahajan
We extend the magnetic connection theorem of ideal magnetohydrodynamics to nonideal relativistic pair plasmas. Adopting a generalized Ohm's law, we prove the existence of generaliz…
Ultrafast Variability in AGN Jets: Intermittency and Lighthouse Effect
Emanuele Sobacchi, Tsvi Piran, Luca Comisso
Gamma-ray flares from Active Galactic Nuclei (AGN) show substantial variability on ultrafast timescales (i.e. shorter than the light crossing time of the AGN's supermassive black h…
Ion and Electron Acceleration in Fully Kinetic Plasma Turbulence
Luca Comisso, Lorenzo Sironi
Turbulence is often invoked to explain the origin of nonthermal particles in space and astrophysical plasmas. By means of 3D fully kinetic particle-in-cell simulations, we demonstr…
Formation of Plasmoid Chains in Fusion Relevant Plasmas
Luca Comisso, Daniela Grasso, François L. Waelbroeck
The formation of plasmoid chains is explored for the first time within the context of the Taylor problem, in which magnetic reconnection is driven by a small amplitude boundary per…
Nonlinear Resistivity for Magnetohydrodynamical Models
Manasvi Lingam, Eero Hirvijoki, David Pfefferlé +2
A new formulation of the plasma resistivity that arises from the collisional momentum-transfer rate between electrons and ions is presented. The resistivity computed herein is show…
Driven Collisionless Reconnection of Force-free Flux Tubes: From Onset to Coalescence
Camille Granier, Daniel Groselj, Luca Comisso +1
We investigate the onset of driven collisionless reconnection and plasmoid formation in a magnetically dominated pair plasma, using 2D Particle-in-Cell simulations. Two force-free…
The contribution of turbulent AGN coronae to the diffuse neutrino flux
Damiano F. G. Fiorillo, Luca Comisso, Enrico Peretti +2
Active galactic nuclei (AGN) can accelerate protons to energies of 10-100 TeV, with secondary production of high-energy neutrinos. If the acceleration is driven by magnetized…
A magnetized strongly turbulent corona as the source of neutrinos from NGC 1068
Damiano F. G. Fiorillo, Luca Comisso, Enrico Peretti +2
The cores of active galactic nuclei (AGN) are potential accelerators of 10-100 TeV cosmic rays, in turn producing high-energy neutrinos. This picture was confirmed by the compellin…
Gyro-induced acceleration of magnetic reconnection
Luca Comisso, Daniela Grasso, François L. Waelbroeck +1
The linear and nonlinear evolution of magnetic reconnection in collisionless high-temperature plasmas with a strong guide field is analyzed on the basis of a two-dimensional gyrofl…
Fast X-ray Variability from the Coronae of Supermassive Black Holes
Xiurui Zhao, Luca Comisso, Stefano Marchesi +4
We present the first systematic study of short-timescale X-ray variability in radio-quiet active galactic nuclei (AGN), utilizing archival Chandra observations of approximately 3,0…
Emergence and Detection of Electron-Scale Current Sheets in Turbulence with MMS Observations and fully kinetic 3D simulations
Zachary Davis, Alexandros Chasepis, Colby Haggerty +2
The solar wind is characterized by turbulence, where a cascade produces intermittent current structures called current sheets (CS) that efficiently dissipate energy into the plasma…
On the Value of the Reconnection Rate
Luca Comisso, Amitava Bhattacharjee
Numerical simulations have consistently shown that the reconnection rate in certain collisionless regimes can be fast, on the order of , where and are the…
Ultra-High-Energy Cosmic Rays Accelerated by Magnetically Dominated Turbulence
Luca Comisso, Glennys R. Farrar, Marco S. Muzio
Ultra-High-Energy Cosmic Rays (UHECRs), particles characterized by energies exceeding eV, are generally believed to be accelerated electromagnetically in high-energy astr…
Magnetic Reconnection as a Mechanism for Energy Extraction from Rotating Black Holes
Luca Comisso, Felipe A. Asenjo
Spinning black holes store rotational energy that can be extracted. When a black hole is immersed in an externally supplied magnetic field, reconnection of magnetic field lines wit…
Thermal-inertial effects on magnetic reconnection in relativistic pair plasmas
Luca Comisso, Felipe A. Asenjo
The magnetic reconnection process is studied in relativistic pair plasmas when the thermal and inertial properties of the magnetohydrodynamical fluid are included. We find that in…
Turbulence Mode Decomposition and Anisotropy in Magnetically Dominated Collisionless Plasmas
Samuel T. Sebastian, Siyao Xu, Yue Hu +3
We use the 3D fully kinetic simulation to study different turbulence modes and turbulence anisotropy of relativistic turbulence in magnetically dominated collisionless plasmas. We…
Non-resonant particle acceleration in strong turbulence: comparison to kinetic and MHD simulations
Virginia Bresci, Martin Lemoine, Laurent Gremillet +3
Collisionless, magnetized turbulence offers a promising framework for the generation of non-thermal high-energy particles in various astrophysical sites. Yet, the detailed mechanis…
Generalized Magnetofluid Connections in Curved Spacetime
Luca Comisso, Felipe A. Asenjo
The ideal magnetohydrodynamic theorem on the conservation of the magnetic connections between plasma elements is extended to non-ideal relativistic plasmas in curved spacetime. The…
Fluid moments of the Landau collision operator
Eero Hirvijoki, Manasvi Lingam, David Pfefferlé +3
One important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this Let…
A Maximum Entropy Principle for inferring the Distribution of 3D Plasmoids
Manasvi Lingam, Luca Comisso
The Principle of Maximum Entropy, a powerful and general method for inferring the distribution function given a set of constraints, is applied to deduce the overall distribution of…
Plasmoid Instability in Evolving Current Sheets and Onset of Fast Reconnection
Yi-Min Huang, Luca Comisso, A. Bhattacharjee
The scaling of plasmoid instability maximum linear growth rate with respect to Lundquist number in a Sweet-Parker current sheet, , indicates that at high…
Neutrinos and gamma rays from Seyfert galaxies constrain the properties of coronal turbulence
Federico Testagrossa, Damiano F. G. Fiorillo, Luca Comisso +3
The TeV neutrino signal observed by IceCube from the active galactic nucleus (AGN) NGC 1068 can probe its innermost coronal regions. If these neutrinos originate from hadrons accel…
Relativistic Magnetic Reconnection in Kerr Spacetime
Felipe A. Asenjo, Luca Comisso
The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used…
Intermittency in Collisionless Large-Amplitude Turbulence
Ryan Golant, Luca Comisso, Philipp Kempski +1
Large-amplitude turbulence -- characterized by a fluctuating magnetic field component, , that is stronger than the mean component, -- is generically intermittent, popula…
Pitch-Angle Anisotropy Imprinted by Relativistic Magnetic Reconnection
Luca Comisso, Brian Jiang
Radiation emitted by nonthermal particles accelerated during relativistic magnetic reconnection is critical for understanding the nonthermal emission in a variety of astrophysical…
The interplay of magnetically-dominated turbulence and magnetic reconnection in producing nonthermal particles
Luca Comisso, Lorenzo Sironi
Magnetized turbulence and magnetic reconnection are often invoked to explain the nonthermal emission observed from a wide variety of astrophysical sources. By means of fully-kineti…
Role of the Plasmoid Instability in Magnetohydrodynamic Turbulence
Chuanfei Dong, Liang Wang, Yi-Min Huang +2
The plasmoid instability in evolving current sheets has been widely studied due to its effects on the disruption of current sheets, the formation of plasmoids, and the resultant fa…
Reconnection-Driven Energy Cascade in Magnetohydrodynamic Turbulence
Chuanfei Dong, Liang Wang, Yi-Min Huang +3
Magnetohydrodynamic turbulence regulates the transfer of energy from large to small scales in many astrophysical systems, including the solar atmosphere. We perform three-dimension…
Interpreting Crab Nebula synchrotron spectrum: two acceleration mechanisms
Maxim Lyutikov, Tea Temim, Sergey Komissarov +3
We outline a model of the Crab Pulsar Wind Nebula with two different populations of synchrotron emitting particles, arising from two different acceleration mechanisms: (i) Componen…
Magnetic Field-Line Curvature and Its Role in Particle Acceleration by Magnetically Dominated Turbulence
Samuel Sebastian, Luca Comisso
We employ first-principles, fully kinetic particle-in-cell simulations to investigate magnetic field-line curvature in magnetically dominated turbulent plasmas and its role in part…
Scalings Pertaining to Current Sheet Disruption Mediated by the Plasmoid Instability
Yi-Min Huang, Luca Comisso, Amitava Bhattacharjee
Analytic scaling relations are derived for a phenomenological model of the plasmoid instability in an evolving current sheet, including the effects of reconnection outflow. Two sce…
Turbulent model of Crab nebula radiation
Yonggang Luo, Maxim Lyutikov, Tea Temim +1
We construct a turbulent model of the Crab Nebula's non-thermal emission. The present model resolves a number of long-standing problems of the Kennel-Coroniti (1984) model: (i) the…
Diffuse neutrino flux from coronal magnetospheric current sheets of accreting black holes
Despina Karavola, Maria Petropoulou, Damiano F. G. Fiorillo +2
Non-jetted AGN exhibit hard X-ray emission with a power law spectrum above 2 keV, which is thought to be produced through Comptonization of soft photons by electrons and posi…
Gravitational electromotive force in magnetic reconnection around Schwarzschild black holes
Felipe A. Asenjo, Luca Comisso
We analytically explore the effects of the gravitational electromotive force on magnetic reconnection around Schwarzschild black holes through a generalized general-relativistic ma…
Reconnection-Driven Turbulent Fluctuations in the Magnetically Dominated Collisionless Regime
Yue Hu, Luca Comisso, Lorenzo Sironi +1
Magnetic reconnection is a fundamental plasma process that converts magnetic energy into bulk flow energy, thermal energy, and nonthermal particle acceleration. Despite its importa…
Intermittency and Dissipative Structures Arising from Relativistic Magnetized Turbulence
Zachary Davis, Luca Comisso, Dimitrios Giannios
Kinetic simulations of relativistic turbulence have significantly advanced our understanding of turbulent particle acceleration. Recent progress has highlighted the need for an upd…
Pitch Angle Anisotropy Controls Particle Acceleration and Cooling in Radiative Relativistic Plasma Turbulence
Luca Comisso, Lorenzo Sironi
Nature's most powerful high-energy sources are capable of accelerating particles to high energy and radiate it away on extremely short timescales, even shorter than the light cross…
TeV neutrinos and hard X-rays from relativistic reconnection in the corona of NGC 1068
Damiano F. G. Fiorillo, Maria Petropoulou, Luca Comisso +2
The recent discovery of astrophysical neutrinos from the Seyfert galaxy NGC 1068 suggests the presence of non-thermal protons within a compact "coronal" region close to the central…
Statistics of Current and Vorticity Structures in Relativistic Turbulence
Zachary Davis, Luca Comisso, Colby Haggerty +1
Coherent structures created through turbulent cascades play a key role in energy dissipation and particle acceleration. In this work, we investigate both current and vorticity shee…
Marginally Stable Current Sheets in Collisionless Magnetic Reconnection
Camille Granier, Dario Borgogno, Luca Comisso +3
Non-collisional current sheets that form during the nonlinear development of magnetic reconnection are characterized by a small thickness, of the order of the electron skin depth.…
Concurrent Particle Acceleration and Pitch-Angle Anisotropy Driven by Magnetic Reconnection: Ion-Electron Plasmas
Luca Comisso
Particle acceleration and pitch-angle anisotropy resulting from magnetic reconnection are investigated in highly magnetized ion-electron plasmas. By means of fully kinetic particle…
Extended theory of the Taylor problem in the plasmoid-unstable regime
Luca Comisso, Daniela Grasso, François L. Waelbroeck
A fundamental problem of forced magnetic reconnection has been solved taking into account the plasmoid instability of thin reconnecting current sheets. In this problem, the reconne…
Multidisciplinary Science in the Multimessenger Era
Eric Burns, Christopher L. Fryer, Ivan Agullo +82
Astrophysical observations of the cosmos allow us to probe extreme physics and answer foundational questions on our universe. Modern astronomy is increasingly operating under a hol…
Generalized Magnetofluid Connections in Relativistic Magnetohydrodynamics
Felipe A. Asenjo, Luca Comisso
The concept of magnetic connections is extended to non-ideal relativistic magnetohydrodynamical plasmas. Adopting a general set of equations for relativistic magnetohydrodynamics i…
Collisionless Magnetic Reconnection in Curved Spacetime and the Effect of Black Hole Rotation
Luca Comisso, Felipe A. Asenjo
Magnetic reconnection in curved spacetime is studied by adopting a general relativistic magnetohydrodynamic model that retains collisionless effects for both electron-ion and pair…
Visco-Resistive Plasmoid Instability
Luca Comisso, Daniela Grasso
The plasmoid instability in visco-resistive current sheets is analyzed in both the linear and nonlinear regimes. The linear growth rate and the wavenumber are found to scale as $S^…
Hard Synchrotron Spectra from Magnetically Dominated Plasma Turbulence
Luca Comisso, Emanuele Sobacchi, Lorenzo Sironi
Synchrotron emission from astrophysical nonthermal sources usually assumes that the emitting particles are isotropic. By means of large-scale two- and three-dimensional particle-in…
Particle Acceleration in Relativistic Plasma Turbulence
Luca Comisso, Lorenzo Sironi
Due to its ubiquitous presence, turbulence is often invoked to explain the origin of nonthermal particles in astrophysical sources of high-energy emission. With particle-in-cell si…
PACHA: Probing AGN Coronae with High-redshift AGN
Xiurui Zhao, Elias Kammoun, Marco Ajello +18
The X-ray emission of active galactic nuclei (AGN) is generally attributed to inverse Compton scattering of accretion-disk photons by hot electrons in a compact corona. In local AG…
Magnetic Connections in Curved Spacetime
Felipe A. Asenjo, Luca Comisso
The ideal MHD theorem on the conservation of the magnetic connections between plasma elements is generalized to relativistic plasmas in curved spacetime. The connections between pl…