On August 17th at 8:41 AM ET, scientists detected gravitational waves from the collision of two neutron stars 130 million lightyears away from earth. Not only was this event seen by high-tech equipment, it was also detectable by regular light telescopes. This means that scientists were just granted unprecedented insight into this massive cosmic collision.
The Laser Interferometer Gravitational-Wave Observatory’s (LIGO) telescopes were scheduled to shut off in August, but just before that time came, their observatories in Washington and Louisiana detected faint signals of gravitational waves. Gravitational waves were first observed in September of 2015, but only through special equipment under the watch of LIGO. For many, this meant that discovery wasn’t validated since there was no external verification that what was observed was actually gravitational waves. However, with this new observation of gravitational waves made in visible light, their existence can be wholly confirmed as well as the concrete validation of Einstein’s theory of general relativity.
Three gravitational wave observatories picked up this most recent event in August. With these three different data points, astronomers were able to pinpoint exactly where the merger of neutron stars occurred down to a small patch of sky.
Round and round they go - then BOOM! This animation begins with the final moments of two neutron stars (the super-dense cores of exploded massive stars), whirling around each other in a galaxy 130 million light-years away. Gravitational waves (rippling disturbance in space-time, shown here as pale arcs) bleed away orbital energy, causing the stars to move closer together and merge. As the stars collide, this explosive event emits light across a series of different wavelengths - first gamma rays (magenta), then ultraviolet (violet), then visible and infrared (blue-white to red) and once the jet directed toward us expanded into our view from Earth, X-rays (blue). Our Fermi Gamma-Ray Space Telescope witnessed this event on August 17, 2017 and we watched it unfold over multiple days with a variety of other telescopes, including the Swift spacecraft, the Hubble Space Telescope (@NASAHubble), the Spitzer Space Telescope, our Chandra X-Ray Observatory (@NASAChandraXray) and our NuSTAR mission. The detectors at the Laser Interferometer Gravitational-Wave Observatory (LIGO) received a gravitational wave signal just 1.7 seconds before the first light was seen by Fermi, making this the first event observed in both light and gravitational waves. Credit: @NASAGoddard/CI Lab #space #nasa #universe #galaxy #stars #astrophysics #astronomy #science #gammarays #ultraviolet #infrared #xrays #gravitationalwaves #neutronstars #hubble #chandra #spitzer #nustar #fermi #swift
After the location was pinpointed, LIGO spread the word to the astronomy community and quickly, 70 ground-based telescopes searched the sky for the remnants of the explosion. They quickly found it.
Gravitational waves are so important to our understanding of physics because they essentially validate the theory of general relativity. Einstein’s theory predicted a series of gravitational waves emanating from the merger of two black holes, which is exactly what the September 2015 observance proved. Scientists have focused specifically on the merging of large objects, like black holes and neutron stars to detect gravitational waves. As these two objects grow closer to one another, spinning increases in frequency until the rotation is several times per second. This rapid cycle results in large gravitational waves that travel through our universe at the speed of light. In both of these previous cases, although faded, they have been detected by instruments here on earth.
This discovery was the first made through the observance of colliding neutron stars and is perhaps the most important made by LIGO to date. Black holes, while perfect for detecting gravitational waves, because they do not allow any light to be emitted, they made pinpointing where the event occurred very difficult. Now, because the discovery was made through neutron stars, scientists were able to pinpoint the location and observe the event’s effects.
Until this most recent discovery, light was the only way that astronomers could study objects in space. This new discovery proves that both light and gravitational waves can be used to study new celestial events. This gives scientists and astronomers a new point of data beginning the era of “multi-messenger astronomy.”
Not only does this new discovery mark a ground-breaking validation achievement in astronomy, it also begins the astronomical revolution of multi-messenger astronomy. With two data collection points for celestial events, future research will be far accelerated and making new discoveries will only be easier.
This momentous discovery will forever change how we understand the universe around us…
written by Trevor English