Gravitational waves bring people to an unprecedented phenomenon in astronomical history

The press conference at 21:00 on October 16, 2017 gave information that is somewhat "dynamic" and very rewarding for the gravitational wave.

The press conference held by scientists from LIGO and VIRGO projects and 70 observatories around the world took place at 21:00 on October 16, 2017 according to Vietnam time. The discovery is rated as unprecedentedly large in terms of gravitational waves - which has helped three American scientists win the Nobel Prize in physics a few weeks ago.

The press conference was attended by:

1. France Córdova - Director of the National Science Foundation
2. David Reitze - CEO of Caltech LIGO
3. David Shoemaker - LIGO / MIT project spokesperson
4. Jo van den Brand - a spokesman for VirgO project
5. Julie McEnery - NASA scientist from Fermi project
6. Marica Branchesi - scientist from Virgo
7. Vicky Kalogera - astrophysicist of LIGO

What did they find this time?For the first time in history, scientists around the world have captured an image of a collision between two neutron stars, 130 million light-years away. The event named GW170817.

Here, gravitational waves are the factors that help science do that. By capturing gravitational waves from the collision, we know where to focus our observations, and know what to grasp. This is also the first time that gravitational waves are observed with optical waves at the same time.

For the first time in history, people witnessed this terrible event with their own eyes.

In other words, this is the first time we ever get to the beginning of the gravitational wave, and observe that event. More importantly, this is only the fifth time we have observed gravitational waves.

Repeat a bit about gravitational waves. If the universe is considered water or air, gravitational waves are very similar to water waves or sound waves. When a terrifyingly large event happens - like two black holes combined - they will create vibrations that spread in every direction at the speed of light.

The gravitational wave was first mentioned in general relativity of genius scientist Albert Einstein in 1916. But it was not until 100 years later that mankind officially confirmed the existence of this type of wave, thanks to LIGO project.

Diagram of LIGO system

The first four confirmed waves are from the event that two cosmic black holes combine into one, but we cannot observe the event. The first reason is because we only have two LIGO systems located in two states of the United States, making it impossible to locate the first three gravitational waves.

In the fourth wave, we have added the Virgo system in Italy, thereby increasing the ability to accurately locate 10 times higher. But that is not enough, because black holes have absorbed all the light - that is, essentially, invisible.

The collision between two extremely massive objects - like two black holes - will produce observable gravitational waves.

This time is different. Neutron stars are objects that emit light, so it is clear that collisions between such 2 stars can be easily observed. And to capture this moment, up to 70 observatories worldwide have collaborated with LIGO and Virgo projects. They observed the constellation Hydra, right next to the galaxy NGC 4993.

The first signal appeared on August 17 from a device belonging to LIGO's system. And only 1.7 seconds later, two NASA and ESA observatories received an extremely intense, glowing and energetic gamma ray burst from the same airspace.

It was not a coincidence, and almost all astronomers around the world immediately directed all their devices towards the Hydra constellation. The explosion is determined by the collision between two neutron stars.

Neutron stars are the form of a supernova star at the "end of life" stage.

For those who do not know, neutron stars are a form of a superstar star at the "end of life" stage. It collapses, compressing protons and electrons into neutrons and neutrinos. The neutrinos then escape, but the neutron is very tight on the star's core, with a diameter of only about 10-20km.

The pair is collectively known as GW170817, with mass falling in the range of 1.1 to 1.6 mass stars (if the number 3 exceeds, the neutron star will collapse, becoming a black hole). They revolve around each other at a distance of 300km, twisting around the space-time around, creating waves of oscillations that spread throughout the universe.

You can observe GW170817 in the video below. The brightest point in the middle is the galaxy NGC 4993 , and a little to the upper left (the point to change color) is the place where the GW170817 event takes place.

The collision created extremely intense gamma streams, thereby enabling people to directly observe an "unprecedented" phenomenon , 130 million light-years away from Earth.

But that is not all."For decades, science has suspected that such gamma-ray bursts are caused by neutron stars. But now, thanks to incredible data from LIGO and VIRGO, we have a real answer." Julie McEnery, scientist from NASA's Fermi project excitedly shared.

"The gravitational wave tells us that the colliding object has a mass similar to a neutron star, and that is not a black hole, because gamma rays emit too violently."

Again, this event continues to prove that Einstein was right.

"It shows that the speed of gravitational propagation is equivalent to the speed of light, or just a fraction less than a trillion - that is once again confirming Einstein's prediction since 1915." know.

In the coming time, experts will continue to follow this collision, and learn more about the so-called "kilonova". It was the material state left after the collision. They continue to glow, and gradually dissipate into the universe.

This study will be officially published in Physical Review Letters.

1. What is a Neutron Star?