Imagine a cosmic event capable of producing, in a second, a jet of energy more powerful than all the energy of the Sun throughout its life. The detection of one of these jets is the content of the photograph that illustrates this article, and it has been detected by two colliding galaxies. It is the first ‘snapshot’ of this astronomical event that is obtained , and it is so important because it is the demonstration that the merger of galaxies can produce jets of particles, which travel almost at the speed of light. That energy is emitted in the form of radiation, such as intense radio waves, X-rays, and gamma rays, and is one of the most powerful phenomena in the universe.
Previously, scientists had estimated that these jets could be found in elliptical shaped galaxies, and that they can be formed when two spiral galaxies merge. Now, they have an image that demonstrates this theory.
Vaidehi Paliya is the lead author of the findings, published in the Astrophysical Journal on April 7, 2020: “For the first time, we have encountered two young spiral or disk-shaped galaxies en route to a collision that has produced a powerful jet. of newborn energy, in the center of one of the galaxies “.
The detection also shows that both the energy jet and the galaxies were young and therefore not yet bright enough to ‘blind’ the measuring instruments; but the jet was thin enough to clearly identify its host. As Stefano Marchesi, professor of Physics and Astronomy explains in a statement: “Normally, a jet of these characteristics would emit light so powerful that we could not see the galaxy behind. It is like trying to look at an object and someone pointing a flashlight at your eyes. All you can see is the flashlight. This jet is less powerful, so we can see the galaxy where it was born . “
Detection instruments
The team, researchers from the Clemson University College of Sciences, captured the image using one of the world’s largest ground-based telescopes: the Subaru 8.2-meter optical infrared telescope located on top of a mountain in Hawaii. They made subsequent observations with the Gran Telescopio de Canarias, in Spain, and the William Herschel Telescope on the island of La Palma, as well as with the space telescope of NASA’s Chandra X-ray Observatory.
How are these jets of energy produced?
The fact that these galaxies are young comes as a surprise to scientists. It was previously thought that jets of energy were born from older elliptically shaped galaxies with an active galactic nucleus (AGN), which is a supermassive black hole residing at their center.
As a point of reference, scientists believe that all galaxies have supermassive black holes located in the center, but not all are AGN. For example, the massive black hole in our Milky Way, Sagittarius A, is dormant.
Scientists theorize that AGNs grow by gravitationally attracting gas and dust through a process called accretion. But not all of this material accumulates in the black hole. Some of the particles are accelerated and spewed outward in jet-like beams.
“Eventually, all the gas will be expelled into space and, without gas, a galaxy can no longer form stars. Without gas, the black hole will turn off and the galaxy will remain inactive,” the researchers point out.
Is this the fate of the Milky Way?
Billions of years from now, our own galaxy, the Milky Way, will merge with the ‘nearby’ Andromeda galaxy. Scientists have carried out detailed numerical simulations and predicted that this event could lead to the formation of a giant elliptical galaxy. Depending on your conditions, this collision could also cause jets of energy like the one in the photograph, but it’s hard to tell.
Referencia:
Vaidehi S. Paliya et al, TXS 2116−077: ‘A Gamma-Ray Emitting Relativistic Jet Hosted in a Galaxy Merger’, The Astrophysical Journal (2020). DOI: 10.3847/1538-4357/ab754f
