News Excerpt:

Scientists from the Aryabhatta Research Institute of Observational Sciences (ARIES)have discovered the impact of plasma composition on the dynamics of astrophysical jets from celestial bodies such as black holes, neutron stars, and pulsars.

What are Astrophysical jets ?

• Astrophysical jets are outflows of ionized matter that are emitted as extended beams from celestial objects such as black holes, neutron stars, and pulsars.
• Despite years of research, it is not known what kind of matter astrophysical jets are composed of.
• Whether they are made of bare electrons or protons or whether positively charged electrons called positrons are also present.
• Knowing the jet composition is vital as it will allow us to pinpoint on the exact physical process at work near black holes and neutron stars.
• In theoretical studies the relation between thermodynamic quantities of the jet like mass density, energy density and pressure do not have the information of composition. 

Findings:

• Researchers upgraded a numerical simulation code to study jets composed of electrons, positrons, and protons, revealing new insights into their behavior and propagation speeds.
• The researchers showed that the change in plasma composition leads to 
• the difference in propagation velocities of the jets even if the initial parameters for the jets remain the same. 
• Contrary to expectations, jets composed of electrons and positrons were slower than those containing protons. 
• The electron-positron jets show more pronounced turbulent structures. The growth of these structures also results in the deceleration of the jets. 
• The formation and growth of turbulent structures are known to affect the stability of the jets. Hence, plasma composition may also influence the long-term stability of the jets.

 Significance of the finding:

This finding is crucial for understanding the physical processes near black holes and neutron stars, potentially solving the longstanding mystery of jet composition.