Relativistic jets from quasars may not be very different from those observed in other types of black holes, according to a new paper published in the journal The Astrophysical Journal🇧🇷 The authors show that, in both cases, the jets are collimated, that is, concentrated in a single beam.
Quasars, one of the most energetic objects in the universe, are the cores of galaxies that have a supermassive black hole in full swing — that is, devouring matter. The process is similar to other active black holes, but quasars are much more powerful.
When captured, the matter is transformed into an accretion disk made of plasma rotating at great speed around the black hole’s equator, producing high levels of radiation. In fact, accretion disks are one of the most efficient energy producers in the universe.
In some cases, part of the energy from the disks is directed towards the poles of the black holes and ejected in the form of jets at relativistic speed (close to that of light). Astronomers still don’t understand the intricate details of these phenomena, but the new study could shed some light.
The authors are an international group of scientists who carried out observations of the object 3C 273, the first quasar identified by mankind, and also the closest to the Milky Way. Observation data show the innermost and deepest parts of the quasar’s plasma jet.
One of the mysteries to be solved is how and where relativistic jets are collimated. In other words, astronomers want to know why their radiation doesn’t scatter, but stays focused in a single beam hundreds of thousands of light years away.
With the jet image of 3C 273, scientists had for the first time a view of the innermost part of a quasar jet, where collimation takes place. The team found that the angle of the stream of plasma flowing from the black hole is further reduced at a farther distance.
This narrow part of the jet continues incredibly far away, reaching distances well beyond the area where the black hole’s gravity dominates. “This has also been discovered nearby in much weaker and less active supermassive black holes,” said Kazunori Akiyama, project leader.
Now researchers want to know “how jet collimation happens so consistently in such varied black hole systems,” says Akiyama. The study is the first step towards a broader exploration of jet collimation processes, thanks to data obtained with a network formed by the largest radio telescopes in the world.
Such a network is composed of the Global Millimeter VLBI Array (GMVA) and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, connected through a technique called very long baseline interferometry (VLBI). The High Sensitivity Array has also joined forces to study 3C 273 at different scales.
The GMVA used eight antennas from the Very Long Baseline Array (VLBA), the Effelsberg Radio Telescope from the Max-Planck-Institut für Radioastronomie (MPIfR), the IRAM Telescope, among others. ALMA is a partnership of the European Southern Observatory, NSF, and NINS from Japan, among other representatives from Canada, Taiwan and the Republic of Korea.
It is hoped that the Event Horizon Telescope, responsible for the two real images of black holes taken by humanity, will be able to carry out the study by observing jets from more distant quasars to find out exactly how they are collimated.