ASTROPHYSICAL JETS - SCIENCE
News: Scientists have investigated how the composition of plasma affects the
dynamics of astrophysical jets, which are outflows of ionized matter emitted as
beams from celestial bodies like black holes, neutron stars, and pulsars.
What’s in the news?
- The exact composition of astrophysical jets is unknown; they may
consist of electrons, protons, and/or positrons (positively charged
electrons).
- Understanding jet composition is crucial for pinpointing the
physical processes occurring near black holes and neutron stars.
- The equation of state (EOS) describes the relationship between
thermodynamic quantities like mass density, energy density, and pressure,
without considering jet composition.
- A new relativistic EOS, partly proposed by scientists from ARIES,
incorporates the composition of relativistic plasma and its impact on jet
dynamics
Astrophysical jets
- Astrophysical jets are highly energetic, narrow beams of matter and
energy that are ejected from the regions surrounding certain types of
astronomical objects, such as black holes, neutron stars, and young
stellar objects.
- These jets can travel at speeds close to the speed of light and
extend across vast distances in space.
Types of Astrophysical Jets
- Relativistic Jets
·
Origin: Usually associated with black holes in
active galactic nuclei (AGN), quasars, and microquasars.
·
Speed: Close to the speed of light.
·
Features: Highly collimated, often exhibit Doppler
boosting and relativistic beaming.
- Non-relativistic Jets
·
Origin: Typically found in young stellar objects,
protostars, and certain types of binary star systems.
·
Speed: Significantly slower than the speed of
light, often a few hundred km/s.
·
Features: Less collimated compared to relativistic
jets, can be observed in various wavelengths such as infrared and radio.
Formation Mechanisms
- Accretion Disks
o
Jets are often formed in the regions surrounding
accretion disks around black holes, neutron stars, or young stars.
o
Magnetic fields in the accretion disk play a crucial
role in launching and collimating the jets.
- Magnetohydrodynamic (MHD) Processes
o
Interaction between the magnetic fields and ionized
plasma in the disk.
o
The twisting of magnetic field lines can create a
magnetic spring that accelerates particles along the field lines, forming jets.
- Radiation Pressure
o
In some cases, radiation pressure from the central
object can help drive the outflow of matter in the form of jets.
Examples of Astrophysical Jets
- Active Galactic Nuclei (AGN) Jets
o
Associated with supermassive black holes at the
centers of galaxies.
o
Can extend for thousands to millions of
light-years.
o
Example: The jet from the galaxy M87, famously
imaged by the Event Horizon Telescope.
- Microquasars
o
Stellar-mass black holes or neutron stars with
jets.
o
Example: SS 433 and GRS 1915+105.
- Young Stellar Objects (YSOs)
o
Protostars or young stars in the process of
forming.
o
Example: Herbig-Haro objects, which are visible
manifestations of jets from YSOs interacting with the surrounding medium.
- Gamma-Ray Bursts (GRBs)
o
Highly energetic explosions thought to be
associated with the collapse of massive stars or mergers of neutron stars.
o
Jets in GRBs are responsible for the intense
gamma-ray emissions observed.
Significance in Astrophysics
- Jets provide insights into high-energy processes and the behavior
of matter under extreme conditions.
- Study of jets helps understand the physics of accretion, magnetic
fields, and relativistic flows.
- Jets can influence the evolution of galaxies by regulating star
formation and heating the interstellar medium.
o
AGN jets, in particular, play a role in the
feedback processes that affect galaxy formation and evolution.
- Observations of jets in distant quasars help probe the early
universe and the growth of supermassive black holes.
Source: https://pib.gov.in/PressReleseDetailm.aspx?PRID=2031586