A5018220928- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Astro and Planetary Science
- Ionosphere and magnetosphere dynamics
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Laser-Plasma Interactions and Diagnostics
- Cosmology and Gravitation Theories
- Smart Agriculture and AI
- Nuclear reactor physics and engineering
- Astrophysics and Star Formation Studies
- Neutrino Physics Research
- Microbial Inactivation Methods
- Innovations in Aquaponics and Hydroponics Systems
- Transportation Safety and Impact Analysis
- Fusion materials and technologies
- Atmospheric Ozone and Climate
- CCD and CMOS Imaging Sensors
- Atomic and Subatomic Physics Research
- Automotive and Human Injury Biomechanics
- Water Quality Monitoring Technologies
PBMA's H.V. Desai Eye Hospital
2024
Savitribai Phule Pune University
2024
Ben-Gurion University of the Negev
2013-2023
Princeton University
2016-2023
Princeton Plasma Physics Laboratory
2021
Mahatma Gandhi Institute of Technology
2021
Institute for Plasma Research
2016-2017
Abstract In-situ measurements taken by the Voyager 2 spacecraft suggest that solar wind termination shock is significantly affected presence of pickup ions are produced in inner heliosphere due to charge exchange between interstellar neutrals and ions. We use a fully kinetic particle-in-cell method self-consistently simulate with all physical properties available from . have performed set simulations varying velocity distribution functions for ions, since it was not determined ’ s...
Non-thermal pickup ions (PUIs) are created in the solar wind (SW) by charge-exchange between SW (SWIs) and slow interstellar neutral atoms. It has long been theorized, but not directly observed, that PUIs should be preferentially heated at quasi-perpendicular shocks compared to thermal SWIs. We present situ observations of hydrogen (H+) an interplanetary shock New Horizons' Solar Wind Around Pluto (SWAP) instrument ~34 au from Sun. At this shock, H+ only a few percent total proton density...
A heliospheric termination shock (HTS) surrounds our solar system at approximately 100 astronomical units from the Sun, where expanding wind (SW) is compressed and heated before encountering interstellar medium. HTS-accelerated particles govern pressure balance with medium, but little known about HTS's global properties beyond in situ measurements Voyager only two directions of sky. We fill this gap knowledge a novel complex methodology: particle-in-cell, test particle, MHD simulations,...
The dynamics of two initially unmagnetized relativistic counter-streaming homogeneous ion–electron plasma beams are simulated in dimensions (2D) using the particle-in-cell (PIC) method. It is shown that current filaments, which form due to Weibel instability, develop a large-scale longitudinal electric field direction opposite carried by filaments as predicted theory. This field, partially inductive and electrostatic, identified main source net electron acceleration, greatly exceeding...
The expected anisotropy in the 1 to 104 TeV energy range is calculated for Galactic cosmic rays with both diffusion tensor and source discreteness taken into account. We find that if sources are distributed radially (but azimuthal symmetry) proportion pulsars, almost always exceeds observational limits by one order of magnitude case isotropic diffusion. If radial more than an smaller rate, gradient can be accommodated about 5% time. concentrated spiral arms, then depends on our location...
Abstract We seek to understand the quantitative role of dominant physical processes (charge-exchange, adiabatic heating, stochastic acceleration) governing proton distribution in heliotail using observations hydrogen energetic neutral atoms (ENAs) from Interstellar Boundary Explorer ( IBEX ). solve Parker transport equation for solar wind protons and pickup ions (PUIs) as they propagate termination shock (TS) down heliotail, including charge-exchange between source terms derived an MHD-fluid...
Abstract The heliospheric energetic neutral atom spectrum observed by the Interstellar Boundary Explorer (IBEX) reveals that heliosheath proton distribution is consistent with a power law. origin of likely from interstellar pickup ions (PUIs) accelerated at termination shock (HTS). We present an explanation using test particle simulation PUIs HTS. experience preferential heating motional electric field in foot, but do not develop power-law tail without presence turbulence wavenumbers ( k )...
Abstract The effects of turbulence in the very local interstellar medium (VLISM) have been proposed by Giacalone & Jokipii to be important determining structure Interstellar Boundary Explorer ( IBEX ) ribbon via particle trapping magnetic mirroring. We further explore this effect simulating motion charged particles a turbulent field superposed on large-scale mean field, which we consider either spatially uniform or draped derived from three-dimensional magnetohydrodynamic simulation....
Abstract We use Interstellar Boundary Explorer ( IBEX ) measurements of energetic neutral atoms (ENAs) to constrain the proton (mostly pickup ion, PUI) distribution in heliotail. In our previous study, we solved Parker transport equation and found that velocity diffusion coefficient D v for PUIs is approximately ∼ 1.1 × 10 −8 km 2 s −3 / 0 1.3 , assuming initial processed by termination shock (TS), f p ,0 a kappa with index κ = 1.63. this test different forms . find if kappa-distributed any...
We simulate decaying turbulence in a homogeneous pair plasma using three dimensional electromagnetic particle-in-cell (PIC) method. A uniform background magnetic field permeates the such that pressure is times larger than thermal and generated by counter-propagating shear Alfv\'en waves. The energy predominately cascades transverse to field, rendering anisotropic at smaller scales. simultaneously move several ion species of varying charge mass ratios our simulation show particles are heated...
We study the time dependent propagation of sub-ankle ultra-high energy cosmic rays (UHECRs) originating from point-like Galactic sources. show that drift in magnetic field (GMF) may play an important role UHECRs and their measured anisotropy, particularly when transport is anisotropic. To fully account for discreteness UHECR sources space time, a Monte Carlo method used to randomly place Galaxy. The low anisotropy by Auger not generally characteristic theoretical models, given are...
ABSTRACT It is suggested that essentially all UHECRs we detect, including those at the highest energies, originate in our Galaxy. shown even if density of sources decreases with Galactic radius, then anisotropy and composition can be understood. Inward anisotropy, as recently reported by Auger collaboration understood drift along current sheet UHECRs, originating outside solar circle, predicted Kumar & Eichler, while within circle exit Galaxy high latitudes.
The hypothesis is considered that the present, local Galactic cosmic-ray spectrum is, due to source intermittency, softer than average over time and Galaxy. Measurements of muogenic nuclides underground could provide an independent measurement time-averaged spectrum. Source intermittency also account for surprising low anisotropy reported by IceCube Collaboration. Predictions emission ultrahigh-energy (UHE) quanta, such as UHE gamma rays neutrinos, might be higher or lower previously estimated.
The variation in the intensity of cosmic rays at small angular scales is attributed to interstellar turbulence vicinity Solar system. We show that {a turbulent origin small-scale structures implies that} morphology observed cosmic-ray skymap varies with our location turbulence. gyroradius shown be length scale associated an observable change over a radian scale. extent which \mpo{at certain} proportional maximum about amplitude existing skymap.} suggest for TeV measurable could occur time...
We present the largest optical photometry compilation of Gamma-Ray Bursts (GRBs) with redshifts ($z$). include 64813 observations 535 events (including upper limits) from 28 February 1997 up to 18 August 2023. also a user-friendly web tool \textit{grbLC} which allows users visualization photometry, coordinates, redshift, host galaxy extinction, and spectral indices for each event in our database. Furthermore, we have added Gamma Ray Coordinate Network (GCN) scraper that can be used collect...
Abstract A "heliospheric" termination shock (HTS) surrounds our solar system at approximately 100 astronomical units from the Sun, where expanding wind is compressed and heated before encountering interstellar medium. HTS-accelerated particles govern pressure balance with medium, but little known about HTS’s global properties beyond in situ measurements Voyager only two directions of sky. We fill this gap knowledge a novel complex methodology: particle-in-cell, test particle, MHD...
The expected anisotropy in the 1 to 104 TeV energy range is calculated for Galactic cosmic rays with diffusion tensor and source discreteness both taken into account. We find that if sources are distributed radially (but azimuthal symmetry) proportion pulsars, almost always exceeds observational limits by one order of magnitude case isotropic diffusion. If radial more than an smaller rate, gradient can be accommodated about 5 percent time. concentrated spiral arms then depends on our...
Context. The remote observations of solar flare ion acceleration are rather limited. There theoretical predictions for signatures in EUV line profiles. Previous tests involve flares with no evidence energetic ions. Aims. We aim to examine a source impulsive (or 3He-rich) particle events spectroscopy. Methods. inspect all (90+) reported 3He-rich previous cycle 23 and find only four (recurrent) jets the field view SOHO CDS. jet most suitable spatial temporal coverage is analyzed detail....