Physicists and astronomers – from all over the world – are still excited after one of the biggest breakthroughs of the decade related to the discovery of gravitational waves and gamma rays’ existence, thanks to the collaboration LIGO-Virgo.
I want to make a small reference on gamma rays that are usually thought to be produced directly from planets or starts in the Universe. They are the product of subatomic particles (usually protons and electrons) that get accelerated in extreme environments typically associated with violent events.
In fact, explosions, outbursts and powerful jets accelerate particles to nearly the speed of light. Gamma Rays are produced when the particles collide with matter and radiation fields in or around the sources or in interstellar space. In other words, gamma rays can be saw as “guardians of treasures” when they travel across the Universe to galaxies beyond, transporting with them the secrets of their birthplace…
But now, let’s go back to the initial plot of this article…
The members of the collaboration confirmed this epic detection on 17th of August, after a meticulous analysis of the data picked up by the Fermi Gamma-ray Space Telescope. This is an observation that confirm a theory, everything fit together: gravitational waves were predicted by Albert Einstein a century ago and in this case, have been detected following the collision of two neutron stars 120 million light-years away!
Can I say that this is a truly and beautiful equilibrium within both theoretical and experimental sides of science, that became a unique (somehow merged) protagonist.
Some journalists and experts define this event as the first-ever example of multi messenger astronomy as well as the first chapter for an independent way to measure the expansion rate of the Universe. Of course, as imagined, exciting news will be reported in the upcoming future as the unique aspect of this discovery, that combines measurements of light and gravitational waves open towards us a new era in the study of the Universe.
Let me give you some historical background to properly frame this extraordinary discovery. The first neutron star observed(star defined by a core diameter from 10 to 29 times larger than the Sun) was discovered in 1967 by Antony Hewish and Samuel Okoye. Hewish received the 1974 Nobel prize in Physics for this discovery and in the same year a pair of neutron stars rotating around each other (forming what is generally called a binary star system) was discovered by Dr. Hulse and Dr. Taylor Jr.
This event worth them a Nobel prize in Physics in 1993.
For the ones of you that are not sure about what a neutron star is, let me allow a brief note. A neutron star forms when a star much bigger and brighter than the sun exhausts its thermonuclear fuel supply and explodes into a violent supernova. Within last years, the explosion of extremely dense neutron stars (which are made almost entirely of neutrons) was detected by multiple telescopes across the electromagnetic spectrum, from gamma rays and visible light to radio waves.
Finally, on the 14th of September 2015, physicists working at the collaboration LIGO (Laser Interferometer Gravitational Wave Observatory) between Louisiana and Washington and the VIRGO one in Italy (Càscina, very close to the most know city of Pisa) detect the first gravitational waves produced by the merger of two neutron stars.
This confirmation let the Americans Rainer Weiss, Barry Barish and Kip Thorne (it is interesting why Italian physicists were not mentioned in this award, even if Virgo was the first to detect the signal of this discovery) win the Nobel Prize in October 2017.
This is a milestone in the growing effort by scientists worldwide to unlock the mysteries of the Universe and Earth. Probably the possibility to have new powerful ears into every corner of the Universe is only the first chapter (or maybe the introduction) of this branch of research.
The existence of gravitational waves provides valuable information about the evolution and the signature left after the explosion of neutron stars, as well as the origin of gold and heavy precious metals such as uranium and many others present now on Earth.
Yes, now it’s official: we’ll expect many surprising discoveries in astrophysics along the upcoming years!
Why? Well, until recent years we could only be able to observe and study the Universe through light waves that reached us. This new ability to study gravitational waves is like a system that despite the partial (although sophisticated) sense touch can now benefit from another sense: sight.
The discovery allowed astronomers to combine gravitational waves to the measurement of Hubble constant, which is the rate of expansion of the Universe as a function of distance from Earth. This measurement derives from the analysis of the amplitude and polarization of a gravitational wave that let astronomers determine the distance from its source. Being able to see the galaxy of origin they can determine the red shift (that occurs whenever a light source moves away from an observer) of its light and from this data the velocity it is moving away from Earth.
A victory to remember until the next discovery, for the inhabitants of a place where willingness, study, research and a bit of luck create extreme beauty & quality knowledge.