Why do galaxies become barren?

Why do galaxies become barren?

The color image of the Hubble Space Telescope shows “self-extinguishing galaxies” at a distance of 6 billion light years. The bright center point is a compact area hinting at the merging remnants of

Galaxies, like our Milky Way, are powerful factories that use gravity to form new stars from molecular gaseous hydrogen. Ours creates about one solar mass per year. The galaxy is filled with gas, and we are constantly getting new reserves. The gas enters under the action of gravity, forms new stars and pushes a part beyond the galactic limits. However, some galaxies have lost the process of star birth and it is difficult for astronomers to understand the cause.

The answer may be a bizarre new galactic class, distant by 6 billion light years and arriving in the process of forcibly pushing its own gas. To understand this, we had to question the recent traditional ideas about the termination of star formation.

One way was to explosively push it through an active galactic core. In the center of each galaxy lies a supermassive black hole. When the gas is inside, it is heated before absorption. In this process, energy is released that can actually blow out the rest of the gas volume. This idea seems attractive because we have an energetic mechanism capable of such actions. But in 2007, scientists noticed a set of “self-extinguishing” galaxies that became barren in some other way. Analysis of one of them showed the process of blowing gas at a speed of 3500 times faster than a jet plane, but there was no evidence of gas falling into a black hole. Then is a supermassive black hole really needed or is there another process? Do not forget that the Universe is a difficult place and constantly throws us new surprises.

Using the best galactic images from the Hubble Space Telescope, researchers realized that gas could be pushed out of galaxies with concentrated starlight without the additional involvement of a black hole. The idea is that the stars release light particles that will collide with gas particles and give them a slight boost. The sums of many small jolts are enough to push the gas out of the galaxy at an incredible speed.

These findings allow a new look at self-extinguishing galaxies. The researchers plan to continue the study using the NASA Chandra X-ray Observatory, the Keck Observatory (Hawaii) and the ALMA array (Chile). It is still unclear how common this cause is and whether gas is completely blown out. In the last analysis, it was decided to use ALMA to find a self-extinguishing galaxy in the most dense and cold gas (in fact, this material forms stars). How to prove that the gas is blown out? A detailed study showed that the galaxy is a compact remnant of a violent merger of two galaxies. There are large-scale winds of dense molecular gas, but without traces of the active galactic core.

ALMA uses light with a longer wavelength than visible. Scientists have noticed that carbon monoxide molecules in a gas emit light, which can be observed with an earth telescope. Most of the gas is hydrogen, but it is difficult to discern it from the Earth, so they chose a trace gas. ALMA searched for carbon monoxide and found that this gas moves from the center at a speed of 1000 km / s.

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