LIGO and Virgo Make First Detection of Gravitational Waves Produced by Colliding Neutron Stars
October 16, 2017
For the first time, scientists have directly detected gravitational waves—ripples in space and time—in addition to light from the spectacular collision of two neutron stars. This marks the first time that a cosmic event has been viewed in both gravitational waves and light.
The discovery was made using the U.S.-based Laser Interferometer Gravitational-wave Observatory (LIGO), funded by the National Science Foundation (NSF); the Europe-based Virgo detector; and some 70 ground- and space-based observatories.
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Videos
Ripples of Gravity, Flashes of Light (4m 17s)
On Aug. 17, 2017, the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo detected, for the first time, gravitational waves from the collision of two neutron stars. The event was not only "heard" in gravitational waves but also seen in light by dozens of telescopes on the ground and in space. Learn more about what this rare astronomy event taught us in a new video from LIGO and Virgo.
Credit: LIGO-Virgo
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Last Dance of Neutron Star Pair (0m 41s)
This simulation shows the final stages of the merging of two neutron stars. The merger shown in the simulation is happening much faster in reality, within less than a hundredth of a second, and produces strong gravitational waves. This illustrates one of the possible scenarios for the merger event GW170817, detected by the LIGO-Virgo gravitational-wave network. The result of the merger could have been a neutron star or a black hole, the latter of which is shown here.
Credit: W. Kastaun/T. Kawamura/B. Giacomazzo/R. Ciolfi/A. Endrizzi
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Variety of Gravitational Waves and a Chirp (0m 56s)
The signal measured by LIGO and Virgo from the neutron star merger GW170817 is compared here to previously detected binary black hole mergers. All signals are shown starting at 30 Hertz, and the progression of GW170817 is shown in real time, accompanied by its conversion to audio heard at the end of the movie. GW170817 was observable for more than 30 times longer than any previous gravitational-wave signal.
Credit: LIGO/University of Oregon/Ben Farr
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Jets and Debris from a Neutron Star Collision (0m 41s)
This animation captures phenomena observed over the course of nine days following the neutron star merger known as GW170817. They include gravitational waves (pale arcs); a near-light-speed jet that produced gamma rays (magenta); expanding debris from a "kilonova" that produced ultraviolet (violet), optical and infrared (blue-white to red) emission; and, once the jet directed toward us expanded into our view from Earth, X-rays (blue).
Credit: NASA's Goddard Space Flight Center/CI Lab
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Zooming in on the Source of Gravitational Waves (0m 49s)
This animation shows how LIGO, Virgo,and space-and ground-based telescopes zoomed in on the location of gravitational waves detected August17, 2017 by LIGO and Virgo. By combining data from the Fermi and Integral space missions with data from LIGO and Virgo, scientists were able to confine the source of the waves to a 30-square-degree sky patch. Visible-light telescopes searched a large number of galaxies in that region, ultimately revealing NGC 4993 to be the source of gravitational waves.
Credit: LIGO-Virgo
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Final Flight of a Neutron Star Pair (0m 46s)
This movie shows a possible trajectory of the neutron stars that merged in an event called GW170817. The pair of stars—a neutron star and a normal star—orbit quietly (green),until the normal star goes supernova, spawning a second neutron star and "kicking" the system into an elliptical orbit (purple). The two neutron stars merge and generate gravitational waves, a gamma-ray burst, and a "kilonova" explosion.Other potential lives of the star pair are shown in the thinner lines and circles.
Credit: LIGO-Virgo/Aaron Geller/Northwestern University
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Neutron Star Merger Seen in Gravity and Matter (0m 39s)
This visualization shows the coalescence of two orbiting neutron stars. The left panel contains a visualization of the matter of the neutron stars. The different colored layers are different densities,which have been made transparent to show more structure. The right panel shows how space-time is distorted near the collisions. The spiral wave distortions at the end of the merger propagate to Earth and are measured as gravitational waves.
Credit: Christopher W. Evans/Georgia Tech
▼ Download MP4 (3.4 MB)
Caltech institutional b-roll footage is available at /broll
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Images
Neutron Star Merger Seen in Gravity and Matter
This visualization shows the coalescence of two orbiting neutron stars. The right panel contains a visualization of the matter of the neutron stars.The left panel shows how space-time is distorted near the collisions.
Credit: Karan Jani/Georgia Tech
▼ Download original (2100 x 1500, JPG, 1.5 MB)
Virgo Helps Localize Gravitational-Wave Signals
Sky localizations of gravitational-wave signals detected by LIGO beginning in 2015 (GW150914, LVT151012, GW151226, GW170104), and, more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2017, scientists were betterable to localize the gravitational-wave signals. The background is an optical image of the Milky Way. The localizations of GW150914, LVT151012, and GW170104 wrap around the celestial sphere, so the sky map is shown with a translucent dome.
Credit: LIGO/Virgo/NASA/Leo Singer (Milky Way image: Axel Mellinger)
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First Optical Photons from Gravitational-Wave Source
Swope and Magellan telescope optical and near-infrared images of the first optical counterpart to a gravitational-wave source, SSS17a, in its galaxy, NGC 4993. The left image is from August 17, 2017, 11 hours after the LIGO-Virgo detection of the gravitational-wave source, and contains the first optical photons from the source. The right image is from four days later, when SSS17a—the aftermath of a neutron star merger—faded significantly and its color became much redder.
Credit: 1M2H/UC Santa Cruz and Carnegie Observatories/Ryan Foley
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GW170817: A Global Astronomy Event
A map of the approximately 70 light-based observatoriesthat detected the gravitational-wave event called GW170817. On August 17, the LIGO and Virgo detectors spotted gravitational waves from two colliding neutron stars. Light-based telescopes around the globe observed the aftermath of the collision in the hours, days, and weeks following. They helped pinpoint the location of the neutron stars and identified signs of heavy elements, such as gold, in the collision's ejected material.
Credit: LIGO-Virgo
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Masses of Neutron Stars and Black Holes
The masses of stellar remnants are measured in many different ways. This graphic shows the masses for black holes detected through electromagnetic observations (purple); the black holes measured by gravitational-wave observations (blue);neutron stars measured with electromagnetic observations (yellow); and the masses of the neutron stars that merged in an event called GW170817, which were detected in gravitational waves(orange). The remnant of GW170817 is unclassified, and labeled as a question mark.
Credit: LIGO-Virgo/Frank Elavsky/Northwestern University
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Cataclysmic Collision
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.
Credit: NSF/LIGO/Sonoma State University/A. Simonnet
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The Sources of the Elements in the Periodic Table
Elements like hydrogen and helium originated in the Big Bang. Heavier elements up to iron are forged in the cores of stars such as supernovae. The electromagnetic radiation captured from GW170817 now confirms that the elements heavier than iron are synthesized in the aftermath of neutron star collisions.
Credit: Jennifer Johnson/SDSS / CC BY 2.0 (modified)
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Media Contacts
LIGO-LSC-MIT/Kimberly Allen, +1 617-253-2702; allenkc@mit.edu
LIGO-Caltech/Emily Velasco, +1 626-395-6487; evelasco@caltech.edu
LIGO-Caltech/Deborah Williams-Hedges, +1 626-395-3227; debwms@caltech.edu
LSC-Georgia Tech/Jason Maderer, +1 404-385-2966; maderer@gatech.edu
NSF/Aya Collins, +1 703-292-7737; acollins@nsf.gov
Virgo-EGO/Séverine Perus, +39 050 752 325; severine.perus@ego-gw.it
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