Emission of compact active radio sources

Illustration (1): The nucleus of an active galaxy and proces of matter accretion onto a supermassive black hole – artist's impression. (Image source: NASA)

Active galaxies are one such type of object. Their activity is driven by the accretion of matter onto supermassive black holes located at their centers. Active galaxies emit radiation across almost the entire electromagnetic spectrum.

In a recently published scientific article, we analyzed the wide-range emission of three compact radio sources. These are galaxies whose radio lobes are very young (on a cosmic scale!) and filled with relativistic electrons. Since their lobes are small (on a galactic scale!), they are relatively close to the accretion disk and dust torus, which emit photons in the ultraviolet and infrared ranges. These photons, colliding with relativistic electrons present in the radio lobes, can gain energy through the inverse Compton effect. As a result, they become X-ray photons. In addition, the relativistic electrons themselves emit radio waves in a process called synchrotron radiation.

In our work, we have modeled the broad-band emission originating from young, compact radio lobes. X-ray emission from active galaxies is usually attributed to the so-called accretion disk corona. Using a model of relativistic electron emission and data from many different telescopes, we have shown that the radio lobes of young radio sources emit significant amounts of X-rays and may be its main source in the case of this class of objects.

What is more, we have identified a relation between the energy distribution of electrons in radio lobes and the degree of X-ray absorption. We are currently working on confirming this correlation. If proven true, it could provide valuable information about the relationship between electron acceleration mechanisms and the properties of gas in the galaxy.