phenomenon

neutron star binary merger

A collision of two neutron stars producing gravitational waves and electromagnetic signals like fast radio bursts.
45 related articles

Description

A neutron star binary merger is a catastrophic event where two neutron stars, the ultra-dense remnants of massive stars, spiral together and collide. This process releases an enormous amount of energy, primarily in the form of gravitational waves, and produces a burst of electromagnetic radiation across the spectrum, including gamma-ray bursts and, potentially, fast radio bursts. These mergers are also the primary site for the production of heavy elements like gold and platinum through the r-process.

History

The first confirmed neutron star binary merger was detected on August 17, 2017, by the LIGO and Virgo gravitational-wave observatories, accompanied by a gamma-ray burst (GRB 170817A) and a kilonova (AT2017gfo). This event, GW170817, marked the beginning of multi-messenger astronomy with gravitational waves.

How it works

The two neutron stars orbit each other, losing energy through gravitational wave emission, which causes their orbits to shrink. As they approach, tidal forces distort them, and eventually they merge into a single, more massive object, either a larger neutron star or a black hole. The merger ejects a small amount of neutron-rich matter, which undergoes rapid neutron capture (r-process) to form heavy elements. The event is observed as a short gamma-ray burst (sGRB) and a kilonova, an optical/infrared transient powered by radioactive decay of the ejected material.

In practice

Neutron star mergers are used to measure the expansion rate of the universe (Hubble constant) via standard sirens, and to study the equation of state of nuclear matter at extreme densities.

Fun fact

The gold in your jewelry was likely forged in a neutron star merger that occurred billions of years ago.

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