Plasma Astrophysics — Research Examples

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Photo: H. Yan
Particle trajectories in turbulent magnetic field

Cosmic ray acceleration and transport

we study the fundamental plasma processes that govern the particle transport and acceleration in various astrophysical settings, the interaction with MHD turbulence, waves, etc.

 

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Photo: H. Yan
Particle trajectories in turbulent magnetic field
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Photo: Zhang et.al. 2020 Nature Astronomy
Turbulence modes in the Cygnus-X-Area over a gamma-ray map of the Fermi-LAT

Properties of MHD turbulence from observational and theoretical studies

The nature of MHD turbulence is shaped by means of energy injection on large scales, damping on small scales as well as environmental factors. New diagnostics are being developed for tracing the plasma properties of interstellar turbulence in conjunction with MHD and PIC simulations.

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Photo: Zhang et.al. 2020 Nature Astronomy
Turbulence modes in the Cygnus-X-Area over a gamma-ray map of the Fermi-LAT
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Photo: H. Yan
Barplot of energy fracs in MHD turbulence

MHD and plasma processes

MHD processes and plasma instabilities in astrophysics are not only the fundamental properties of the space plasma, but also very interesting because of the unique conditions that can never be realized in laboratory, e.g., huge size span, collisionless, extreme temperatures.

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Photo: H. Yan
Barplot of energy fracs in MHD turbulence
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Photo: H. Yan
The first 3D magnetic field detection with atomic alignment

Astrophysical Magnetic Fields:  dynamics and detections

Astrophysical Magnetic fields as glue of astrophysical plasma, magnetic field is out of question one of the key properties that we want to know.

We investigate various ways to detect magnetic fields and their dynamics (turbulence), in particular, in the diffuse media.

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Photo: H. Yan
The first 3D magnetic field detection with atomic alignment
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Photo: Liu, Yan, Zhang 2019
Multi-wavelength flux from Geminga predicted from anisotropic diffusion model in comparison with measurements

High Energy Astrophysics

High energy phenomena ranging from solar flares, PWNes and SNRs to gamma ray bursts.

We seek to incorporate our understandings on basic particle plasma interactions to various high energy phenomena.

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Photo: Liu, Yan, Zhang 2019
Multi-wavelength flux from Geminga predicted from anisotropic diffusion model in comparison with measurements
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Photo: Ge, He, Yan 2016
Chemistry evolution owing to dust dynamics in turbulence

Interstellar Dust Dynamics

Dust grain is one of the key components in interstellar medium.

They are intimately linked to the magnetic field and plasma as charge carriers in addition to their major rules in metallically and light propagation. All those are much determined by their dynamics, which we investigate.

 

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Photo: Ge, He, Yan 2016
Chemistry evolution owing to dust dynamics in turbulence
2D energy spectrum of the Alfvenic component of the MHD turbulence
Photo: S. Zhao+ 2022
2D energy spectrum of the Alfvenic component of the MHD turbulence from the multi-spacecraft data analysis, revealing the scale dependent anisotrophy

Space Plasma Physics

We are investigating physical processes in space plasma, where rich information can be revealed by the measurement directly from various space probes, including the recently launched “Parker space probe". In particular, we are analysing the MHD perturbations, particle transport and plasma instabilities.                                                    Here is a representative plot with caption:

2D energy spectrum of the Alfvenic component of the MHD turbulence
Photo: S. Zhao+ 2022
2D energy spectrum of the Alfvenic component of the MHD turbulence from the multi-spacecraft data analysis, revealing the scale dependent anisotrophy