Astrophysics & Particle Physics-APPC 2026

Neutron Stars are the dense remains of very massive stars that have exploded as supernovae. With masses normally ranging from 1.4 to 2 times the mass of the Sun squeezed into a radius of only roughly 10–15 kilometers, neutron stars have densities so extreme that matter is in phases not elsewhere present in the universe. Neutron stars are composed mostly of neutrons, bound together by gravity and nuclear forces, and have very peculiar physical characteristics such as fast rotation, intense magnetic fields, and powerful gravitational attraction. Most neutron stars are seen as pulsars, which emit beams of radiation that sweep over Earth at periodic times, serving as accurate astrophysical clocks.

Some neutron stars, magnetars, have magnetic fields that are trillions of times stronger than the Sun and create intense X-ray and gamma-ray bursts. Neutron stars in binary systems may accrete matter from companion stars, building up accretion disks and X-rays visible to space telescopes.Neutron star mergers are one of the major sources of gravitational waves, detected by LIGO and Virgo detectors. Mergers also help create heavy elements through r-process nucleosynthesis, enriching the universe with gold, platinum, and other heavy elements. The study of these mergers gives us insights into extreme physics, nuclear matter properties, and the mechanisms of cosmic heavy element formation.Observations of neutron stars over the electromagnetic spectrum, ranging from radio and X-rays to gamma rays, allow astrophysicists to investigate their internal composition, magnetic field dynamics, and evolutionary histories.

Numerical simulations and theoretical models supplement observations, enabling scientists to learn about the properties of matter in extreme densities, pressures, and magnetic fields.Neutron stars are a key phase of stellar evolution, connecting massive stars with black holes. Investigations in this area advance the understanding of high-energy astrophysical phenomena, relativistic effects, and dense matter's fundamental physics, rendering neutron stars one of the most intriguing objects in contemporary astrophysics.