49 citations · 226 across the 20 of their papers we have counts for
16 papers · 1 filter
Impact of Cosmic Ray Distribution on the Growth and Saturation of Bell Instability
Saikat Das, Siddhartha Gupta, Prateek Sharma
Cosmic rays (CRs) streaming in weakly magnetized plasmas can drive large-amplitude magnetic fluctuations via nonresonant streaming instability (NRSI), or Bell instability. Using on…
Speed-dependent Threshold for Electron Injection into Diffusive Shock Acceleration
Siddhartha Gupta, Damiano Caprioli, Anatoly Spitkovsky
Finding the injection threshold for diffusive shock acceleration (DSA) of electrons in collisionless shocks has been a longstanding unsolved problem. Using first-principles kinetic…
Nonthermal Signatures of Radiative Supernova Remnants II: The Impact of Cosmic Rays and Magnetic Fields
Rebecca Diesing, Siddhartha Gupta
Near the ends of their lives, supernova remnants (SNRs) enter a "radiative phase," when efficient cooling of the postshock gas slows expansion. Understanding SNR evolution at this…
Understanding Streaming Instabilities in the Limit of High Cosmic Ray Current Density
Emily Lichko, Damiano Caprioli, Benedikt Schroer +1
A critical component of particle acceleration in astrophysical shocks is the non-resonant (Bell) instability, where the streaming of cosmic rays (CRs) leads to the amplification of…
Electron Acceleration at Quasi-parallel Non-relativistic Shocks: A 1D Kinetic Survey
Siddhartha Gupta, Damiano Caprioli, Anatoly Spitkovsky
We present a survey of 1D kinetic particle-in-cell simulations of quasi-parallel non-relativistic shocks to identify the environments favorable for electron acceleration. We explor…
Return Currents in Collisionless Shocks
Siddhartha Gupta, Damiano Caprioli, Anatoly Spitkovsky
Collisionless shocks tend to send charged particles into the upstream, driving electric currents through the plasma. Using kinetic particle-in-cell simulations, we investigate how…
The saturation of the Bell instability and its implications for cosmic ray acceleration and transport
D. Caprioli, G. Zacharegkas, C. Haggerty +2
The non-resonant (Bell) streaming instability driven by energetic particles is crucial for producing amplified magnetic fields that are key to the acceleration of cosmic rays (CRs)…
Evidence for multiple shocks from the -ray emission of RS Ophiuchi
Rebecca Diesing, Brian D. Metzger, Elias Aydi +4
In August of 2021, Fermi-LAT, H.E.S.S., and MAGIC detected GeV and TeV -ray emission from an outburst of recurrent nova RS Ophiuchi. This detection represents the first very hig…
Modeling the Saturation of the Bell Instability using Hybrid Simulations
Georgios Zacharegkas, Damiano Caprioli, Colby Haggerty +2
The nonresonant streaming instability (Bell instability) plays a pivotal role in the acceleration and confinement of cosmic rays (CRs); yet, the exact mechanism responsible for its…
A Kinetic Study of the Saturation of the Bell Instability
Georgios Zacharegkas, Damiano Caprioli, Colby Haggerty +1
The nonresonant cosmic ray instability, predicted by Bell (2004), is thought to play an important role in the acceleration and confinement of cosmic rays (CR) close to supernova re…
Cosmic rays from massive star clusters : A close look at Westerlund 1
Sourav Bhadra, Siddhartha Gupta, Biman B. Nath +1
We study the effect of cosmic ray (CR) acceleration in the massive compact star cluster Westerlund 1 in light of its recent detection in -rays. Recent observations reveal a $1/r…
Non-resonant Streaming Instability driven by Leptons
Siddhartha Gupta, Damiano Caprioli, Colby Haggerty
Using fully-kinetic plasma simulations, we study the non-resonant (Bell) streaming instability driven by energetic leptons. We identify the necessary conditions to drive it and the…
Lepton-driven Non-resonant Streaming Instability
Siddhartha Gupta, Damiano Caprioli, Colby C. Haggerty
A strong super-Alfvénic drift of energetic particles (or cosmic rays, CRs) in a magnetized plasma can amplify the magnetic field significantly through non-resonant streaming instab…
Realistic modeling of wind and supernovae shocks in star clusters: addressing and other problems in Galactic cosmic rays
Siddhartha Gupta, Biman B. Nath, Prateek Sharma +1
Cosmic ray (CR) sources leave signatures in the isotopic abundances of CRs. Current models of Galactic CRs that consider supernovae (SNe) shocks as the main sites of particle accel…
Modeling the Saturation of the Bell Instability Using Hybrid Simulations
Georgios Zacharegkas, Damiano Caprioli, Colby Haggerty
The nonresonant cosmic ray instability, predicted by Bell (2004), is thought to play an important role in the acceleration and confinement of cosmic rays (CRs) close to supernova r…
A numerical approach to the non-uniqueness problem of cosmic ray two-fluid equations at shocks
Siddhartha Gupta, Prateek Sharma, Andrea Mignone
Cosmic rays (CRs) are frequently modeled as an additional fluid in hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations of astrophysical flows. The standard CR two-fluid mod…