Global Understanding of Accretion and Ejection around Black Holes Ⅱ

Dear Colleagues,

Accretion and ejection flows around astrophysical bodies play an important role in astrophysics and cosmology, on both small and large scales. This field of study is expanding and growing rapidly following the launch of different space-based satellites and ground-based telescopes in multi-wavelength bands, leaving a range of questions on accretion and ejection mechanisms. The recent discovery of classic black hole images by the Event Horizon Telescope network and gravity waves opened a new window for studying these type of objects in isolation or as a binary system. 

With the advent of high-resolution observations, it is possible to address global problems in a more holistic and consistent way. Recently, many new low-mass black hole candidates have been discovered; however, very little is known about these systems. On the other hand, in large scale applications, many new changing look active galactic nuclei (CLAGN) have been discovered; however, the physical origin of CL behavior remains uncertain. Research into spectral and timing domains also requires a proper understanding of spectral state change, quasi periodic oscillation frequency evolution, hardness intensity diagrams, and line emissions. Furthermore, in the case of extreme blazar-like objects, it is believed that a jet can be powered by the amplification of propagating fluctuation in the accretion disk. Therefore, it is a good time to take a break, reflecting upon previous findings, evaluating current research, and contemplating future directions in upcoming projects, both from a theoretical and observational perspective, bringing together experts across the electromagnetic spectrum to gain new insights into the physical process of accretion and ejection.

The goal and motivation of this Special Issue are to focus on top-quality original works and comprehensive review papers within the above-mentioned context, with important research findings that are written in a very understandable way, and focus on either theoretical, observational, and numerical simulation grounds, where observational papers will describe measurements for testing theoretical and numerical (both hydrodynamic or magnetohydrodynamic) understandings. Copied and pasted text or fabricated papers with inconsistencies in their writing will not be considered in this Special Issue.

This collection will provide a compact and concise description of the overall view of the subject: its past, present, and future.

Dr. Santanu Mondal
Guest Editor

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• black holes
• X-ray binaries
• accretion
• accretion disks
• jets
• quasi-periodic oscillations
• hydrodynamics
• LMBHBs
• AGNs
• ULXs
• hydrodynamics
• MHD
• shocks
• viscosity
• radiative transfer
• line emission
• X-ray instrumentation