riassunto2

AC2 - MHD processes near compact object

Speaker

Mondal, Tushar

Coauthors

Mondal, Tushar; Mukhopadhyay, Banibrata

Talk Title

Magnetised 1.5-Dimensional Advective Accretion Flows Around Black Holes

Abstract

The outward transport of the angular momentum of accreting matter leads to the accretion flow and formation of disc around the compact objects. Here, we discuss the importance of large scale strong magnetic field in the removal of angular momentum outward, as well as the possible origin of different kinds of magnetic barrier in advective, geometrically thick, sub-Keplerian accretion flows around black holes. The origin of this large scale strong magnetic field near the event horizon is due to the advection of the magnetic flux by the accreting gas from the environment, say, the interstellar medium or a companion star, because of flux freezing. In this simplest vertically averaged, 1.5-dimensional disc model, we choose the maximum upper limit of the magnetic field, which the disc around a black hole can sustain. In this circumstance, the accreting gas either decelerates or faces the magnetic barrier near the event horizon by the accumulated magnetic field depending on the geometry. We suggest that these types of flow are the basic building block to produce jets and outflows in the accreting system. We also find that in some cases, when matter is trying to go back to infinity after knocking the barrier, it is prevented being escaped by the cumulative action of strong gravity and the magnetic tension, hence by another barrier. In this way, magnetic field can lock the matter in between these two barriers and it might be a possible explanation for the formation of episodic jet.

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