arXiv subjects

Murchana Khusroo

Publications and source records attributed to Murchana Khusroo.

4 recordsLinked to original sources

arXiv2026

A Multi-Diagnostic Observational Framework for Magnetosonic Solitary Waves During Geomagnetic Storms in Solar Cycles 24 and 25 using Cluster II Mission

Solitary structures, commonly known as solitons, are a class of nonlinear plasma waves that are abundantly found in near-Earth plasmas and planetary magnetospheres. They are nonlinear, localized plasma waves that maintain their shape and velocity over time and distance. While their occurrence in various space plasma environments has been extensively reported, their observation during geomagnetic storms, large-scale disturbances driven by interactions between the solar wind and Earth's magnetosphere, remains limited. In this study, we present a comparative investigation of magnetosonic soliton signatures during geomagnetic storms associated with Solar Cycles 24 and 25. Using high-resolution in-situ magnetic field measurements from the Cluster II mission, we systematically examine the plasma conditions favorable for soliton generation and their evolution during storm-time dynamics. A comprehensive multi-diagnostic observational framework, incorporating several state-of-the-art analytical techniques, is developed to reliably detect and characterize magnetosonic solitons. The results demonstrate that solitary structures in both storms predominantly occur during the early storm intervals, prior to the main phase, suggesting that they may serve as potential precursor signatures of enhanced geomagnetic activity.

astro-ph.SR↗

arXiv2025

Observation of Alfven solitons in the solar corona using Parker Solar Probe (PSP) and Solar and Heliospheric Observatory (SOHO)

Solitons are predominantly observed in near-earth plasmas as well as planetary magnetospheres; however, their existence in the solar corona remains largely unexplored, despite theoretical investigations. This study aims to address this gap by examining the presence and dynamics of solitons in the solar corona, particularly in the context of coronal heating. Utilizing observational data from the Parker Solar Probe (PSP) and Solar and Heliospheric Observatory (SOHO) during the onset of a strong Coronal Mass Ejection (CME) event, the analyses reveal a train of aperiodic solitons with increasing amplitude preceding the eruption. A key finding of this study is that the observed aperiodic soliton train serves as a potential candidate in facilitating energy transfer through dissipation within the coronal plasma, hereby, influencing the initiation of solar eruptive events such as a CME. A defining characteristic of this solitary train is its hypersonic and super-Alfvenic nature, evident from the presence of high Mach numbers that reinforces its role in plasma energy equilibration in the solar corona, thereby contributing to plasma heating.

astro-ph.SR↗

arXiv2023

Fast-moving electrostatic solitons in a plasma with turbulence heating

In this work, it is shown that electrostatic solitons in a plasma with turbulent heating of the electrons through an accelerating electric field can form with very high velocities, reaching up to several order of magnitudes larger than the equilibrium ion-sound speed. The possible parameter regime, where this work may be relevant, can be found in the so-called "dead zones" of a protoplanetary disk. Though these zones are stable to magnetorotational instability, the resultant turbulence can in fact heat the electrons making them follow a highly non- Maxwellian velocity distribution. We show that these fast-moving solitons can reach very high velocities. With electron velocity distribution described by the Davydov distribution function, we argue that these solitons can be an effective mechanism for energy equilibration in such a situation through soliton decay and radiation.

physics.plasm-ph↗

arXiv2015

Solitary structures with ion and electron thermal anisotropy

Formation of electrostatic solitary structures are analysed for a magnetised plasma with ion and electron thermal anisotropies. The ion thermal anisotropy is modelled with the help of the Chew-Goldberger-Low (CGL) double adiabatic equations of state while the electrons are treated as inertia-less species with an anisotropic bi-Maxwellian velocity distribution function. A negative electron thermal anisotropy $(T_{e\perp}/T_e{\parallel}>1)$ is found to help form large amplitude solitary structures which are in agreement with observational data.

physics.plasm-ph↗