Lagrangian Description of Accreting Black Hole Systems in the Context of Emergent Spacetime

Abstract

We make use of the Lagrangian description of fluid motion to highlight certain features in the context of spacetime geometry as emergent phenomena in fluid systems. By using Lagrangian Perturbation Theory (LPT), we find that if the flow is not barotropic it will not be locally irrotational, and as a result, emergent gravity can not be realised for such flow. Our work gives a new perspective of examining the perturbations in a fluid from a different approach (other than Eulerian approach) which is the way of using Lagrangian Perturbation Theory. We make use of Lagrangian description of motion to examine the propagation of Eikonal wave (wave having very short wavelength) from the reference frame of the observer moving with the background flow. We find that waves of ultra short wavelength propagate similar to waves in a static uniform medium in the near vicinity of the observer. We restrict ourselves to nonrelativistic flows in astrophysical black hole accretion.

arXiv comment20 pages. 7 figures (colour). arXiv admin note: text overlap with arXiv:1807.02586

References in corpus (5)

• Multi-transonic Black Hole Accretion Discs with Isothermal Standing Shocks
• Dependence of General Relativistic Accretion on Black Hole Spin
• The role of flow geometry in influencing the stability criteria for low angular momentum axisymmetric black hole accretion
• Transonic Black Hole Accretion as Analogue System
• Black Hole spin dependence of general relativistic multi-transonic accretion close to the horizon

Cited by in corpus (4)

• Influence of flow thickness on general relativistic low angular momentum accretion around spinning black holes
• Simulating gravity in rotational flow
• Dependence of acoustic surface gravity on disc thickness for accreting astrophysical black holes
• Emergent gravity through non-linear perturbation