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Some of the most energetic pulsars exhibit rotation-modulated gamma-ray emission in the $0.1$ to $100$ GeV band. The luminosity of this emission is typically $0.1\text{-}10\%$ of the pulsar spin-down power (gamma-ray efficiency), implying…
High-energy astrophysical systems frequently contain collisionless relativistic plasmas that are heated by turbulent cascades and cooled by emission of radiation. Understanding the nature of this radiative turbulence is a frontier of…
Using our new 3-D relativistic electromagnetic particle (REMP) code parallelized with MPI, we investigated long-term particle acceleration associated with a relativistic electron-positron jet propagating in an unmagnetized ambient…
A solution to the sigma problem - that of finding a mechanism capable of converting Poynting energy flux to particle-borne energy flux in a pulsar wind - was proposed several years ago by Coroniti and Michel who considered a particular…
Magnetic reconnection is invoked as an efficient particle accelerator in a variety of astrophysical sources of non-thermal high-energy radiation. With large-scale two-dimensional particle-in-cell simulations of relativistic reconnection…
Advances in ultra-intense laser technology are enabling, for the first time, relativistic intensities at mid-infrared (mid-IR) wavelengths. Anticipating further experimental research in this domain, we present high-resolution two…
The magnetorotational instability (MRI) is a crucial mechanism of angular momentum transport in a variety of astrophysical accretion disks. In systems accreting at well below the Eddington rate, such as the central black hole in the Milky…
The magnetorotational instability (MRI) plays a crucial role in regulating the accretion efficiency in astrophysical accretion disks. In low-luminosity disks around black holes, such as Sgr A* and M87, Coulomb collisions are infrequent,…
Basic properties of relativistic magnetic reconnection in electron-positron pair plasmas are investigated by using a particle-in-cell (PIC) simulation. We first revisit a problem by Hesse & Zenitani (2007), who examined the kinetic Ohm's…
Plasmas generated using energetic electron beams are well known for their low electron temperature ($T_{e}$) and plasma potential, which makes them attractive for atomic-precision plasma processing applications such as atomic layer etch and…
We present preliminary results of particle-in-cell simulations of collisionless magnetic reconnection for conditions that apply to magnetically dominated pair plasma jets such as those in gamma-ray bursts. We find similar behaviour to…
Magnetic reconnection has long been known to be the most important mechanism not only for mixing the plasmas by changing the magnetic field topology but also for releasing the magnetic field energy into the plasma kinetic energy. During…
Using 2.5-dimensional Particle-in-Cell simulations, we study the kinetic physics of relativistic shear flow boundary in collisionless electron-positron (e+e-) plasmas. We find efficient magnetic field generation and particle energization at…
Magnetic reconnection is a fundamental plasma process that plays a critical role not only in energy release in the solar atmosphere, but also in fusion, astrophysical, and other space plasma environments. One of the challenges in explaining…
Relativistic magnetic turbulence has been proposed as a process for producing nonthermal particles in high-energy astrophysics. Particle energization may be contributed by both magnetic reconnection and turbulent fluctuations, but their…
In high-Lundquist-number plasmas, reconnection proceeds via onset of tearing, followed by a nonlinear phase during which plasmoids continuously form, merge, and are ejected from the current sheet (CS). This process is understood in fully…
We perform a high-resolution two-dimensional fully-kinetic numerical simulation of a turbulent plasma system with observation-driven conditions, in order to investigate the interplay between turbulence, magnetic reconnection, and particle…
This dissertation explores the interaction between high-intensity lasers and plasmas to accelerate electrons and produce radiation via experimental and computational efforts. The laser pulses used in this dissertation have ultrashort…
Relativistic magnetized jets, such as those from AGN, GRBs and XRBs, are susceptible to current- and pressure-driven MHD instabilities that can lead to particle acceleration and non-thermal radiation. Here we investigate the development of…
The plasma heating during collisionless magnetic reconnection is investigated using particle-in-cell simulations. We analyze the time evolution of the plasma temperature associated with the motion of the reconnecting flux tube, where the…