55 citations · 394 across the 19 of their papers we have counts for
22 papers
The impact of nonlinear Landau damping on cosmic ray streaming and the role of external turbulence
Rouven Lemmerz, Mohamad Shalaby, Ellen Zweibel +2
Cosmic rays (CRs) streaming faster than the Alfvén speed generate Alfvén waves that scatter them. The saturated wave amplitude is regulated by a damping mechanism. This damping con…
Saturation Mechanism of Cosmic Ray Streaming Instabilities with a Shell Distribution
Mohamad Shalaby, Rouven Lemmerz, Christoph Pfrommer
Cosmic rays (CRs) drive galactic winds and regulate galaxy growth while contributing to heating the central cooling plasma in dense galaxy clusters, making the nonlinear saturation…
The Sound of the Universe: A Resonant Gravitational Instability Driven by Baryon-Dark Matter Relative Drift
Mohamad Shalaby, Avery Broderick
Dark matter and baryons acquire a relative velocity after decoupling in the early Universe. Baryons are gravitationally unstable only above their Jeans scale, while cold dark matte…
Effective cosmic ray diffusion in multiphase galactic environments
Timon Thomas, Christoph Pfrommer, Rüdiger Pakmor +2
Cosmic-ray (CR) feedback is widely recognized as a key regulator of galaxy formation. After being accelerated at supernova remnant shocks, CRs propagate through the interstellar me…
The theory of resonant cosmic ray-driven instabilities -- Growth and saturation of single modes
Rouven Lemmerz, Mohamad Shalaby, Christoph Pfrommer +1
Cosmic ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star formation in galaxies, and escape from active galactic nuclei to heat the coo…
Deciphering the physical basis of the intermediate-scale instability
Mohamad Shalaby, Timon Thomas, Christoph Pfrommer +2
We study the underlying physics of cosmic-ray (CR) driven instabilities that play a crucial role for CR transport across a wide range of scales, from interstellar to galaxy cluster…
Coupling multi-fluid dynamics equipped with Landau closures to the particle-in-cell method
Rouven Lemmerz, Mohamad Shalaby, Timon Thomas +1
The particle-in-cell (PIC) method is successfully used to study magnetized plasmas. However, this requires large computational costs and limits simulations to short physical run-ti…
Constraining blazar heating with the 2<z<3 Lyman- forest
A. Lamberts, E. Puchwein, C. Pfrommer +5
The intergalactic medium (IGM) acts like a calorimeter recording energy injection by cosmic structure formation, shocks and photoheating from stars and active galactic nuclei. It w…
The mechanism of efficient electron acceleration at parallel non-relativistic shocks
Mohamad Shalaby, Rouven Lemmerz, Timon Thomas +1
Thermal electrons cannot directly participate in the process of diffusive acceleration at electron-ion shocks because their Larmor radii are smaller than the shock transition width…
A new cosmic ray-driven instability
Mohamad Shalaby, Timon Thomas, Christoph Pfrommer
Cosmic ray (CR)-driven instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify mag…
The growth of the longitudinal beam-plasma instability in the presence of an inhomogeneous background
Mohamad Shalaby, Avery E. Broderick, Philip Chang +3
We study the longitudinal stability of beam-plasma systems in the presence of a density inhomogeneity in the background plasma. Previous works have focused on the non-relativistic…
Missing Gamma-ray Halos and the Need for New Physics in the Gamma-ray Sky
Avery E. Broderick, Paul Tiede, Philip Chang +5
An intergalactic magnetic field stronger than ~G would explain the lack of a bright, extended degree-scale, GeV-energy inverse Compton component in the gamma-ray s…
Growth of beam-plasma instabilities in the presence of background inhomogeneity
Mohamad Shalaby, Avery E. Broderick, Philip Chang +3
We explore how inhomogeneity in the background plasma number density alters the growth of electrostatic unstable wavemodes of beam plasma systems. This is particularly interesting…
Importance of resolving the spectral support of beam-plasma instabilities in simulations
Mohamad Shalaby, Avery E. Broderick, Philip Chang +3
Many astrophysical plasmas are prone to beam-plasma instabilities. For relativistic and dilute beams, the {\it spectral} support of the beam-plasma instabilities is narrow, i.e., t…
Bow Ties in the Sky II: Searching for Gamma-ray Halos in the Fermi Sky Using Anisotropy
Paul Tiede, Avery E. Broderick, Mohamad Shalaby +4
Many-degree-scale gamma-ray halos are expected to surround extragalactic high-energy gamma ray sources. These arise from the inverse Compton emission of an intergalactic population…
SHARP: A Spatially Higher-order, Relativistic Particle-in-Cell Code
Mohamad Shalaby, Avery E. Broderick, Philip Chang +3
Numerical heating in particle-in-cell (PIC) codes currently precludes the accurate simulation of cold, relativistic plasma over long periods, severely limiting their applications i…
Constraints on the Intergalactic Magnetic Field from Bow Ties in the Gamma-ray Sky
Paul Tiede, Avery E. Broderick, Mohamad Shalaby +4
Pair creation on the cosmic infrared background and subsequent inverse-Compton scattering on the CMB potentially reprocesses the TeV emission of blazars into faint GeV halos with s…
The Linear Instability of Dilute Ultrarelativistic Pair Beams
Philip Chang, Avery E. Broderick, Christoph Pfrommer +4
The annihilation of TeV photons from extragalactic TeV sources and the extragalactic background light produces ultrarelativistic beams, which are subject to powerful plas…
Bow Ties in the Sky I: The Angular Structure of Inverse Compton Gamma-ray Halos in the Fermi Sky
Avery E. Broderick, Paul Tiede, Mohamad Shalaby +4
Extended inverse Compton halos are generally anticipated around extragalactic sources of gamma rays with energies above 100 GeV. These result from inverse Compton scattered cosmic…
Patchy blazar heating: diversifying the thermal history of the intergalactic medium
Astrid Lamberts, Philip Chang, Christoph Pfrommer +3
TeV-blazars potentially heat the intergalactic medium (IGM) as their gamma rays interact with photons of the extragalactic background light to produce electron-positron pairs, whic…
The Effect of Nonlinear Landau Damping on Ultrarelativistic Beam Plasma Instabilities
Philip Chang, Avery E. Broderick, Christoph Pfrommer +3
Very-high energy gamma-rays from extragalactic sources pair-produce off of the extragalactic background light, yielding an electron-positron pair beam. This pair beam is unstable t…
Dynamics and Light Propagation in a Universe with Discrete Matter Content
Mohamad Shalaby
We discuss a model for a universe with discrete matter content instead of the continuous perfect fluid taken in FRW models. We show how the redshift in such a universe deviates fro…