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16 October 2017
Optical Systems Capture First Ever Detection of Gravitational Waves from a Pair of Colliding Neutron Stars
16 October 2017
Optical Systems Capture First Ever Detection of Gravitational Waves from a Pair of Colliding Neutron Stars
Multinational research teams view the merger of two neutron stars; ejecting gamma ray streams and clouds of matter that produce heavy elements and light
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 Collaborations (VC) announced the detection of a bright spark of two neutron stars colliding, shedding light on the previously unknown origins of some of the universe's heavy elements. The 17 August event, named GW170817, was detected for 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 explosion. 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.
| Artist’s illustration of two merging neutron stars. The rippling space-time grid represents gravitational waves that travel out from the collision, while the narrow beams show the bursts of gamma rays that are shot out just seconds after the gravitational waves. Swirling clouds of material ejected from the merging stars are also depicted. The clouds glow with visible and other wavelengths of light. Image credit: NSF/LIGO/Sonoma State University/A. Simonnet. |
“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 astrophysics and gravitational waves together impacts how we view our universe. With the combined information from photons and gravitational waves, we are pushing new frontiers in astrophysics, cosmology, fundamental physics and nuclear physics too, and we will refine our measurements as more binary neutron star gravitational wave events are found. This is the first event of this kind, but it will not be the last.”
LIGO’s first detection in September 2015 detected two black holes merging to form a black hole with a solar mass of 62, the highest stellar mass black hole discovered up to that point. A second detection came in December 2015 with a final mass of 21 suns. 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 telescopes and optical-based systems, a separate group of research teams 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, and uranium. 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 but much brighter. 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 was the first to make the optical discovery announced today. The research team noted, amateur astronomers on the earth may be able to ‘see’ more and more of these events in the future night sky.
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Looking to learn more about discoveries from the LIGO Scientific Collaboration?
Watch Dr. Laura Cadonati plenary presentation at the annual meeting of The Optical Society.
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.
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