The mystery of the distant nebula gives astronomers peace

Astronomers are faced with quite an interesting case. In one of the far corners of the Universe discovered a huge glowing bubble of gas, and scientists can't explain what causes it to glow. Discovered nebula located in the center of a giant "protocluster", located about 10 billion light years from Earth and consists of some of the oldest galaxies in the Universe. According to astronomers, the found object is the brightest among the previously found space objects of this type.

Find, under the class of so-called "giant Lyman-alpha nebulae" (enormous Lyman-alpha nebula, ELAN) not only is the brightest object in the Universe of this type, but also the largest. It surpasses even the nebula "Slug", discovered in 2014 and stretchable by more than 2 million light years.

"She's incredibly bright and, most likely, the size of the nebula Slug, but find inside it nothing but blurry shapes of galaxies, we failed," — said Javier Prochaska, one of the researchers from the University of California in Santa Cruz.

"in Other words, we found an incredible size energy phenomenon, but can't find the source of his energy."

To date, scientists know of only a few objects of the class ELAN, but researchers believe that they are part of the so-called cosmic web, entangling the whole Universe and connects galaxies. However, at that time, as a source of illumination other giant Lyman-alpha nebulae is often incredible the radiation level resulting usually within them quasars, Nova and supernova, similar objects in the study of the new nebula, dubbed MAMMOTH-1, scientists were found. Therefore, researchers are unable to understand what exactly makes you glow in the nebula is hydrogen gas emitting the Lyman-alpha radiation (characteristic radiation of atoms of hydrogen).

Interestingly, this problem researchers have faced in 2000, when it was discovered another ELAN object, called "bubble Lyman-alpha 1". It is located in the southern part of the constellation of "Aquarius" is about 11.5 billion years from Earth. The size of this nebula is three times the size of our milky Way galaxy. But despite the fact that it "glows" bright green in the telescopes of astronomers, until now scientists have not been able to identify the source of its glow.

According to a recent speculation, the source of illumination of such objects may be supermassive black holes absorbing matter in galaxies located in the Central region of the nebula. In a new study MAMMOTH-1, scientists came to the same conclusion.

The nebula was discovered in the new surveys of the sky Mapping the Most Massive Overdensities Through Hydrogen (MAMMOTH), which were also found in the Slug nebula. Discovered inside the nebula protocluster incredibly huge (about 50 light years) and contains an unusually dense concentration of galaxies connected with powerful gravity.

Despite the fact that to this point all of these galaxies are very old, in a telescope they look to us as young and appeared only after 3 billion years after the Big Bang. That could cause such a bright glow across the nebula MAMMOTH-1 and protocluster, it was proposed several hypotheses, but the most likely answer to this question is likely to be associated with the so-called "active galactic nucleus". At least so says the current group of scientists involved in the study discovered the nebula.

Active galactic nucleus is a compact region of space at the center of galaxies and, typically, has a much higher luminosity compared to the rest. Scientists explain this by the fact that one of the sources of active galactic nuclei are supermassive black holes actively absorbing gas located in the center of the galaxy. The intense radiation of the active galactic nucleus ionizes around the hydrogen, and it is quite possible, and forces ELAN to throw away such a bright Lyman-alpha glow.

Observations show that most often the source of the brightest active galactic nuclei in the visible light are quasars – the brightest objects in the Universe — but in the case of nebula MAMMOTH-1 no quasars have been discovered. Although, of course, no one excludes the possibility that a dense accumulation of gas and dust nebula, one could still and escape.

"There is a suspicion similarities with active galactic nucleus, however, on optical images, we have no direct evidence thereof was found. Think it might be a quasar hidden behind a very dense accumulation of dust that covers our greater volume of light" — comments of Prochaska.

A Team of researchers, of course, will try to see at least one quasar about 10 billion light years from Earth, but at the moment the source of the glow that ELAN remains a puzzle to them.