Advection-dominated Accretion: Underfed Black Holes and Neutron Stars
Abstract
We describe new optically thin solutions for rotating accretion flows around black holes and neutron stars. These solutions are advection dominated, so that most of the viscously dissipated energy is advected radially with the flow. We model the accreting gas as a two-temperature plasma and include cooling by bremsstrahlung, synchrotron, and Comptonization. We obtain electron temperatures Te 108.5-1010 K. The new solutions are present only for mass accretion rates Mṡcrit less than a critical rate A crit which we calculate as a function of radius R and viscosity parameter α. For Mṡ < Mṡcrit we show that there are three equilibrium branches of solutions. One of the branches corresponds to a cool optically thick flow which is the well-known thin disk solution of Shakura & Sunyaev Another branch corresponds to a hot optically thin flow, discovered originally by Shapiro, Lightman, & Eardley (SLE). This solution is thermally unstable. The third branch corresponds to our new advection-dominated solution. This solution is hotter and more optically thin than the SLE solution but is viscously and thermally stable. It is related to the ion torus model of Rees et al. and may potentially explain the hard X-ray and γ-ray emission from X-ray binaries and active galactic nuclei. For Mṡ < Mṡcrit, our work suggests that an accretion flow can choose between two distinct states, namely, the thin disk solution and the new advection-dominated solution, both of which are apparently stable. We…
Read the paper
Related studies
- A Survey on Knowledge Graphs: Representation, Acquisition, and Applications
- Toxicity of nanomaterials
- The Human Gene Mutation Database: towards a comprehensive repository of inherited mutation data for medical research, genetic diagnosis and next-generation sequencing studies
- Halogen bonding (X‐bonding): A biological perspective
- Biofilm formation at the air–liquid interface by the Pseudomonas fluorescens SBW25 wrinkly spreader requires an acetylated form of cellulose
- Opioid Activation of Toll-Like Receptor 4 Contributes to Drug Reinforcement
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.