Context:
Recently, India’s first multi-wavelength space-based observatory AstroSat has detected bright sub-second X-ray bursts from a new and unique neutron star with ultrahigh magnetic field (magnetar).
Relevance:
GS III: Science and Technology
Dimensions of the Article:
- X-ray Bursts in Low-Mass X-ray Binary Systems
- Magnetar: Neutron Star with Ultra-Powerful Magnetic Field
X-ray Bursts in Low-Mass X-ray Binary Systems
Characteristics:
- Location: Occurs in low-mass X-ray binary systems.
- Participants: Involves a neutron star and a low-mass main sequence star orbiting each other closely.
Process:
- Accretion Disk Formation: Companion star overflows its roche-lobe, leading to the formation of an accretion disk around the neutron star.
- Hydrogen Transfer: Hydrogen from the companion star is drawn into the accretion disk and deposited on the neutron star’s surface.
- Helium Conversion: Extreme temperatures and pressures cause hydrogen to be immediately converted into helium on the neutron star’s surface.
- Helium Build-up: A thin surface layer of helium accumulates until a critical mass is reached.
- Explosive Ignition: Helium ignition results in an explosive release of X-rays, heating the neutron star’s surface to several tens of millions of degrees.
Recurrence:
- Recurrent Bursts: The binary system temporarily returns to a quiescent state, and the neutron star begins to re-accumulate the helium surface layer, leading to recurrent X-ray bursts.
- Interval: Generally occurs at regular intervals, separated by several hours or days.
Magnetar: Neutron Star with Ultra-Powerful Magnetic Field
Definition:
- Type: Exotic neutron star.
- Characteristic: Possesses an ultra-powerful magnetic field.
Magnetic Field Strength:
- Comparison: Magnetic field is about 1,000 times stronger than a normal neutron star and a trillion times stronger than Earth’s.
Energy Release:
- Associated Events: Releases vast amounts of energy in the form of flares, X-rays, and gamma-ray bursts.
- Extreme Events: Often associated with extreme cosmic events, making them among the most peculiar objects in the universe next to black holes.
Magnetic Field Origin:
- Hypothesis: Magnetic field strength may result from the neutron star’s interior, composed of neutrons, quarks, and exotic states of matter, becoming a superconducting fluid.
