On September 14, 2015, our planet experienced a very small space-time ripple, which was detected using a laser interferometric gravitational wave observatory (LIGO). When analyzing the signal, physicists realized that these gravitational waves were caused by the merging of two black holes at a distance of about 1.3 billion light years from Earth. This first gravitational wave detection event was named "GW150914."
The observation, which was announced on February 11 with a global pomp, not only confirmed one of Einstein’s last predictions of the 100-year general theory of relativity, but also showed us that black holes with a mass of about 30 solar ones exist and may turn out to be more common than modern theories predict. This discovery is also the first tantalizing type of astronomy, which in the future will change the way we see the Universe. Gravitational-wave astronomy is a paradigm shift from the electromagnetic spectrum; Now we can see invisible energy events that produce gravitational waves, but cannot produce any electromagnetic manifestations.
Today, however, NASA announced that its cosmic observatory of gravitational waves detected a weak signal close to the predicted source of gravitational waves, which opens up exciting prospects for penetrating the essence of this particular merger of black holes.
NASA's Fermi gamma-ray telescope detected a very weak and short burst of high-energy X-rays corresponding to a short gamma-ray burst (or GRB) less than half a second after LIGO registered GW150914. This is surprising - it was assumed, according to a NASA press release, that when black holes collide, they do it “cleanly” without producing any electromagnetic radiation. So, are there two signals associated with one event? Time makes it very likely; there is only a 0, 2 percent chance that they occurred in the same sky at the same time, but belonged to two different high energy phenomena. “This low-probability, tantalizing discovery may be a false alarm, but before we can begin rewriting the textbooks, we need to see more events related to gravitational waves from the merging of black holes,” said Valery Connoton, a member of the Gamma-ray Burst Monitor team ( GBM) at the National Space, Science and Technology Center in Huntsville, Alabama.
Most HVs are thought to be created when massive stars swell after burning fuel and then explode to form black holes. They are known as sources of intense radiation of "long gamma-ray bursts", which are detected as a flash of gamma rays and high-energy X-rays emanating from the pole of a star at the moment of explosion. There is, however, a more mysterious type of GRB with a short period (less than 2 seconds) and, possibly, it is associated with the confluence of a black hole and a neutron star.
Now that astronomers have access to the spectrum of gravitational waves, the true nature of “short gamma-ray bursts” has probably been found.
“With just one joint event — the joint detection of gamma rays and gravitational rays — it turns out exactly what causes the short GRB,” said Lindy Blackburn, a postdoctoral student at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts and a member of the LIGO scientific collaboration. “There is an incredible interaction between two observations, gamma rays, revealing the details of the source’s energy and local environment and gravitational waves, providing a unique test of the dynamics leading to the event.”
The gravitational wave signal was generated by the rapid unwinding of a helix and the collision of two black holes, an event that created the now famous “tweeting of black holes”. But if in fact the observation of the Fermi telescope is the same event, astrophysicists will have to figure out how this happens. The merging of black holes should not generate a significant amount of energy in the electromagnetic spectrum in the absence of some gas near the confluence region. But it seems that the vast majority of any gases surrounding binary black holes would have disappeared long ago. In short, this weak GRB signal came as a surprise and physicists must decide whether we fully understand the dynamics of black hole mergers or we see some new physics that has remained hidden until now.
Whatever the reason, this is only the beginning of an exciting astronomy era of gravitational waves, which will not only allow us to explore some of the most extreme phenomena in the Universe, no doubt answering many questions, but will also reveal many new space secrets.