Optical systems capture first ever detection of gravitational waves from a pair of colliding neutron
WASHINGTON — For many decades astronomers relied on light for their observations of astronomical objects. Today, a team of scientists from the international LIGO (LSC) and Virgo Scientific Collaborations (VSC) announced the detection of the bright spark of two neutron stars colliding, shedding light on the previously unknown origins of some of the universe's heavy elements. The event, which occurred on 17 August and named GW170817, was more than a minute and a half and covered the full acoustic frequency range sampled by the research team.
Comprised of three enormous laser interferometers located in the USA and Italy, the LIGO and Virgo detectors work together to detect and understand the origins of gravitational waves. The waves detected on 17 August, came from the violent merger of two neutron stars–the dense, dying remnants of massive stars after they undergo a supernova. The research team indirectly observed the debris from the collision moving at speeds so rapid that models suggest they could only be achieved if two of these celestial bodies collided. These two now-famous neutron stars likely formed roughly 11 billion years ago and have finally collided.
"Today, we announced a new era of multi-messenger astronomy," said David H. Reitze, LIGO Executive Director and Fellow of The Optical Society. "It's the first time that we've observed a cataclysmic astrophysical event in both gravitational waves and electromagnetic waves — our cosmic messengers. Gravitational-wave astronomy offers new opportunities to understand the properties of neutron stars in ways that just can't be achieved with electromagnetic astronomy alone. Our goal is to have more gravitational wave detectors coming online in the next two to five years, and we expect to see more discoveries of binary black holes and neutron stars."
Laura Cadonati, deputy spokesperson of the LIGO Scientific Collaboration and associate professor, Georgia Institute of Technology, USA, added, "The optical science research in the areas of high-energy astrophysical neutrinos and gravitational waves, continue to impact how we view our universe. With the combined information we are learning from this discovery, we will continue to do more testing as more gravitational wave events are found. This is the first event but it will not be the last."
LIGO's first detection in September 2015 discovered a black hole with a solar mass of 62. A second detection came in December 2015 with a solar mass of 21. The third detection in June 2016 discovered a black hole with a solar mass of 49 times the sun. On August 14, the Advanced LIGO and Virgo facilities detected the merger of two black holes with masses of about 31 and 25 times the mass of the Sun and located about 1.8 billion light-years away. Using advanced optical-based systems, the research team saw distinct evidence of radiation produced by the matter from the 'kilonova' cooling into heavy elements. A single kilonova can produce an entire Earth's worth of heavy elements, such as; gold, platinum, iron and nickel. At this time, it is unclear if this is a typical result of collisions of this magnitude.
Neutron stars are the smallest, densest stars known to exist and are formed when massive stars explode in supernovas. As these neutron stars spiraled together, they emitted gravitational waves that were detectable for about 100 seconds; when they collided, a flash of light in the form of gamma rays was emitted and seen on Earth about two seconds after the gravitational waves. In the days and weeks following the smashup, other forms of light, or electromagnetic radiation — including X-ray, ultraviolet, optical, infrared, and radio waves — were detected.
Optical telescopes first found a new point of light, resembling a new star. Ultimately, about 70 observatories on the ground and in space observed the event on August 17 at their representative wavelengths. A 16-inch portable telescope enabled the discovery announced today. The research team noted that amateur astronomers on the earth may be able to 'see' more and more of these events in the future night sky.
About the LIGO and Virgo Scientific Collaborations
LIGO is funded by the NSF, and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects. Financial support for the Advanced LIGO project was led by the NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project.
More than 1,200 scientists and some 100 institutions from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration and the Australian collaboration OzGrav. Additional partners are listed at http://ligo.org/partners.php
The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; eight from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in the Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with the University of Valencia; and the European Gravitational Observatory, EGO, the laboratory hosting the Virgo detector near Pisa in Italy, funded by CNRS, INFN, and Nikhef.
About The Optical Society
Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and entrepreneurs who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. For more information, visit osa.org.
Rebecca B. Andersen
The Optical Society
The Optical Society