Magdalena Kunert-Bajraszewska

Instytut Astronomii, Uniwersytet Mikołaja Kopernika

Sesja VII: Kosmologia i ewolucja galaktyk

Czwartek 14.09.2023 16:00 – 16:12

abstrakt:
The evolution of extragalactic sources has been an important issue in the study of active galactic nuclei for many years. Numerous observations led to creation of a standard evolutionary model for radio sources, according to which the younger and smaller Gigahertz-Peaked Spectrum (GPS) and Compact Steep Spectrum (CSS) sources expand and become large-scale FRI and FRII objects. However, the excess of compact sources in comparison to fully developed radio-galaxies indicates that a part of GPS and CSS sources never evolve into extended structures.
Among several explanations for this early cessation of radio activity, there are indications that some sources may be transient objects on timescales of 10^4 – 10^5 years, representing the new population of active galaxies that needs to be explored. This phenomenon is naturally associated with a discussion about the conditions/factors needed to initiate the radio emission in AGNs. My talk will be a subjective look at these issues.