14 DAY TRIAL // Since astronomers started using X-ray observatories, they noticed that the central plane of our galaxy, the Milky Way, shined with great radiation, but that it seemed to come from everywhere. In other words, scientific studies could not reveal any one source for all the X-rays, which seemed to spread from one end of the Milky Way to the other. Now, having used the Chandra X-ray Observatory to take the most deep image of our galaxy's core, astronomers can finally understand why they failed to see the source of radiation.
Simply put, there is not one source. Rather, the glow is generated by millions of tiny sources, which the experts at the Chandra X-ray Center, who were in charge of the investigation, could not explain. The recently investigated area is located just 1.4 degrees off the galactic center, which was only recently proven to contain a supermassive black hole. Detailed readings of the recent study appear in today's (April 30th) issue of the scientific journal Nature.
The X-ray formation, which was observed for the first time more than 20 years ago, using such telescopes as the HEAO-1 and the Exosat observatories, was noticed to extend about two degrees above and below the plane of the galaxy, and about about 40 degrees along its plane, on either side of the galactic core. Despite their best efforts at the time, all the data that astronomers could muster showed that the glow was diffused, which was really confusing.
Regularly, if a massive source of X-rays is detected at the core of a galactic formation, it can only mean that a black hole has taken residence in its bright center. While cannibalizing on nearby gas, matter and dust, taken mostly from its accretion disk, a black hole also emits powerful gamma-ray bursts (GRB), some of which get to be more than 13 billion years old, and still remain powerful after millions of years.
From the recent observations Chandra made, which lasted for about 12 days, investigators selected a portion of the Galactic ridge X-ray emission that was not too far from the center, but also in an area where the interference from dust and gas would be minimal. The portion they selected, which was roughly the same size as three percent of a full Moon, revealed approximately 473 emission sources all by itself, so, by extrapolating the number of potential X-ray generators, the experts concluded that they had to number in the millions.
Most likely, the team said, the sources were nothing but white dwarfs – which are in the habit of pulling matter away from nearby stars –, or maybe binary star systems, in which interactions between the stars can generate large flares. This type of flares is famous for the amounts of X-rays it generates.