Neutron Stars Collide

Scientists have recently detected gravitational waves and light produced by the collision of two neutron stars in a galaxy 130 million light years away. The historic discovery on August 17 was made using the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO); the Europe-based Virgo detector; and some 70 ground- and space-based observatories.

Montclair State physics professors Rodica Martin and Marc Favata are part of the international LIGO Scientific Collaboration team that made the discovery.

This is the first time a collision of two neutron stars — small, dense stars formed when huge stars explode in supernovas — has been detected using gravitational waves. It is also the first time a gravitational-wave signal has been accompanied by coincident detections with conventional telescopes.

In a galaxy 50 times farther away than our neighboring Andromeda galaxy, two neutron stars spiraled toward each other, emitting powerful gravitational waves before colliding and causing a burst of gamma rays. Their collision produced a “chirp” recorded by the LIGO and Virgo detectors that lasted nearly 100 seconds. “This is a really big deal,” says Favata. “Neutron star collisions are a key source LIGO was hoping to observe — and now we have.”

According to Favata, the discovery confirmed a persistent suspicion that short duration gamma ray bursts (GRBs) result from the collision of two neutron stars. Long-standing speculation as to how heavy elements, such as gold and lead, are produced has also been resolved. A byproduct of the collision of the two neutron stars, these elements are distributed throughout the universe.

The new gamma-ray measurements and gravitational-wave detections further confirm Einstein’s theory of relativity and are ushering in the new field of multi-messenger astronomy— which combines information from gravitational waves, light, neutrinos and other forms of radiation produced by cosmic explosions.

Martin helped design and install various components of the detectors’ advanced LIGO upgrade that enabled the recent discoveries. “Currently, I’m developing and designing optical components and instrumentation for future detectors that will help us observe even more distant events,” she says.

While Favata helped develop some of the gravitational-wave models used to analyze neutron star collisions, he and Martin and their students are also involved in LIGO education and outreach efforts, such as the www.soundsofspacetime.org website