Astronomers have built the most complete and detailed image of the relativistic jets of the active galaxy Centaurus A in the radio range. Scientists managed not only to study the structure of jets and estimate the rate of outflow of matter from the center of the galaxy but also to build a model of the dynamics of matter in the galaxy.
Everything you need to know about Centaurus A
Centaurus A is a giant elliptical galaxy and the closest radio galaxy to Earth, located at approximately 12 million light-years away. The active galactic nucleus, containing a supermassive black hole with a mass of 55 million solar masses, is hidden from the terrestrial observer in the optical range due to dense clouds of dust, but it radiates brightly in the X-ray and radio ranges.
It is believed that the galaxy’s strange shape and the burst of star formation in it arose from a collision in the past of a large elliptical galaxy with a small spiral.
One of the most remarkable features of Centaurus A are the relativistic jets of plasma (jets) of the galaxy, tens of thousands of light-years long, for the creation of which the activity of a supermassive black hole is responsible. Previously, they were the target of observations with the Event Horizon Telescope, which received detailed images of them, as well as a number of space and ground-based telescopes.
The data they have collected allows us to understand the mechanisms of jet generation and how they interact with the galaxy’s environment.
Scientists constructed the most detailed image of the relativistic jets of Centaurus A
A group of astronomers led by Benjamin McKinley of Curtin University published the results of observations of Centaurus A using the low-frequency ground-based radio telescope MWA (Murchison Widefield Array) at a frequency of 185 megahertz and with an angular resolution of one and a half arc minutes. Scientists have constructed the most detailed radio image of the galaxy’s jets, which has revealed a number of previously unobserved jet details.
The jets of Centauri A, as they move away from the core, turn into huge emitting regions – radio lobes, each of which consists of an inner (brighter) and an outer part and has a fibrous structure. In the jets, near the nucleus, radiation spots (nodes) are visible, which appear in front of heated gas clouds emitting in the X-ray range during the acceleration of electrons in shock waves or during the interaction of electrons with magnetic fields.
The researchers suggest that the remnants of a dwarf galaxy destroyed by tidal forces are concentrated in the northern radio field.
Additional discoveries and calculations
Scientists have determined that the rate of outflow of matter from the center of Centaurus A into the halo is about 1,100 kilometers per second, and the outflow of mass is 2.9 times the mass of the Sun per year. The accretion rate of matter onto a black hole is estimated at 5.3 × 10 −4 solar masses per year.
The galaxy is best described by a model in which a large-scale halo of hot plasma cools and condenses, forming clouds of cold gas, which then fall into the region of the core, feeding it. In this case, most of the gas is thrown away from the galaxy with the help of jets or outflows, which, as they expand, carry more and more matter with them.
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