What drives the dichotomy in the radio galaxy population?
Andra Stroe
Center for Astrophysics - Harvard & Smithsonian

Powerful radio galaxies are split into two distinct classes (Fanaroff-Riley class I and II, FR-I/II) based on the morphology of their large-scale radio emission. Particle acceleration in the FR-I class occurs close to the central engine, within bright jets that decelerate on scales of 10 kpc. FR-IIs have, on average, higher radio powers and their jets remain highly relativistic out to tens or hundreds of kpcs. The jets terminate in bright hotspots where most of the particle acceleration is thought to occur. One of the biggest challenges in modern radio astronomy is understanding if this dichotomy is driven by black hole engine properties (different accretion), factors internal to the host galaxy (gas clouds in the propagation path of the radio jets), or factors on larger scales (overdense environment). While classical FR-I/II sources comprise the majority of the radio galaxy population, a rare group of hybrid morphology sources (HyMoRS) display differing FR morphologies in each of the two lobes. Over the past few years, the number of newly discovered candidate HyMoRS has significantly grown, with conservative estimates placing HyMoRS at ?5% of the radio AGN population. By allowing the study of differing morphologies resulting from one central black hole engine, HyMoRS offer a unique perspective into the relationship between the two FR classes. I will discuss how recent advances in multiwavelength observations of HyMoRS enable steps toward resolving the FR-I/II dichotomy origin question that has puzzled astronomers for almost 50 years.

Date:	Jeudi, le 10 octobre 2024
Heure:	11:30
Lieu:	Pour tous
	Pavillon MIL A-2521