AC3 - Accretion discs and jets |
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Speaker |
RAYCHAUDHURI, SANANDA |
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Coauthors |
Ghosh, Shubhrangshu ; Joarder, Parthasarathi |
| Talk Title |
Spherical accretion in giant elliptical galaxies: multi-transonicity, shocks, and implications on AGN feedback |
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Abstract |
Isolated massive elliptical galaxies, or that are present at the centre of cool core clusters are believed to be powered by hot gas accretion directly from their surrounding hot X-ray emitting gaseous medium. This leads to a giant Bondi-type spherical/quasi-spherical accretion flow onto their host SMBHs, with the accretion flow region extending well beyond the Bondi radius. In this work, we present a detailed study of Bondi-type spherical flow in the context of these massive ellipticals by incorporating the effect of entire gravitational potential of the host galaxy in the presence of cosmological constant(Λ), considering a 5 component galactic system (SMBH + stellar + dark matter + hot gas + Λ). The galactic contribution to the potential renders the spherical flow to become multi-transonic in nature, with the flow topology and flow structure significantly deviating from that of classical Bondi solution. More notably, corresponding to moderate to higher values of galactic mass-to-light ratios, we obtain Rankine-Hugoniot shocks in spherical wind flows. Galactic potential enhances the Bondi accretion rate. Our study reveals that there is a strict lower limit of ambient temperature below which no Bondi accretion can be triggered; which is as high as ~9 X 10^6 K for flows from hot ISM-phase. Our findings may have wider implications, particularly in the context of outflow/jet dynamics, and radio-AGN feedback, associated with these massive galaxies in the contemporary Universe. |
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