2020MNRAS.499.3178Y -
Mon. Not. R. Astron. Soc., 499, 3178-3192 (2020/December-2)
Spectral and imaging properties of Sgr A* from high-resolution 3D GRMHD simulations with radiative cooling.
YOON D., CHATTERJEE K., MARKOFF S.B., VAN EIJNATTEN D., YOUNSI Z., LISKA M. and TCHEKHOVSKOY A.
Abstract (from CDS):
The candidate supermassive black hole in the Galactic Centre, Sagittarius A* (Sgr A*), is known to be fed by a radiatively inefficient accretion flow (RIAF), inferred by its low accretion rate. Consequently, radiative cooling has in general been overlooked in the study of Sgr A*. However, the radiative properties of the plasma in RIAFs are poorly understood. In this work, using full 3D general-relativistic magnetohydrodynamical simulations, we study the impact of radiative cooling on the dynamical evolution of the accreting plasma, presenting spectral energy distributions and synthetic sub-millimetre images generated from the accretion flow around Sgr A*. These simulations solve the approximated equations for radiative cooling processes self-consistently, including synchrotron, bremsstrahlung, and inverse Compton processes. We find that radiative cooling plays an increasingly important role in the dynamics of the accretion flow as the accretion rate increases: the mid-plane density grows and the infalling gas is less turbulent as cooling becomes stronger. The changes in the dynamical evolution become important when the accretion rate is larger than 10–8 M☉∼ yr–1 (≳10–7 {dot}M_ Edd_, where {dot}M_ Edd_ is the Eddington accretion rate). The resulting spectra in the cooled models also differ from those in the non-cooled models: the overall flux, including the peak values at the sub-mm and the far-UV, is slightly lower as a consequence of a decrease in the electron temperature. Our results suggest that radiative cooling should be carefully taken into account in modelling Sgr A* and other low-luminosity active galactic nuclei that have a mass accretion rate of {dot}M > 10–7 {dot}M_ Edd_.
Abstract Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
accretion, accretion discs - black hole physics - MHD - methods: numerical - stars: jets - galaxies: individual: (SgrA*)
Simbad objects:
4
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2020MNRAS.499.3178Y and select 'bookmark this link' or equivalent in the popup menu