Vorticity, gyroscopic precession, and spin-curvature force

Abstract. In this work, we perform linear perturbation on general relativistic isothermal accretion onto a non-rotating astrophysical black hole to study the salient features of the corresponding emergent acoustic metric. For spherically symmetric accretion as well as for the axially symmetric matter flow for three different geometric configuration of matter, we perturb the velocity potential, the mass accretion rate, and the integral solution of the time independent part of the general relativistic Euler equation to obtain such acoustic geometry. We provide the procedure to locate the acoustic horizon and identify such horizon with the transonic surfaces of the accreting matter through the construction of the corresponding causal structures. We then discuss how one can compute the value of the acoustic surface gravity in terms of the accretion variable corresponding to the background flow solutions -i.e., stationary integral transonic accretion solutions for different matter geometries. We show that the salient features of the acoustic geometry is independent of the physical variable we perturb, but sensitively depends on the geometric configuration of the black hole accretion disc.

show abstract

“…Thus it represents the local rotation of the fluid elements in the flow. In general relativity the vorticity is defined as [12,47] …”

Section: Velocity Potentialmentioning

confidence: 99%

Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric

Shaikh

Firdousi

Das

2017

Class. Quantum Grav.

View full text Add to dashboard Cite

show abstract

“…This is consistent with the fact that PTsymmetry breaking threshold for the lasing edge state is lower than that of bulk modes. Interestingly, the onset of these three phases is also manifested in the complex Berry phase associated with this SSH laser array [33,34]. Figure 4 (d) shows the Berry phase associated with the lower band Φ − as a function of the normalized gain η when ν = 2.…”

mentioning

confidence: 98%

Edge-Mode Lasing in 1D Topological Active Arrays

et al. 2018

View full text Add to dashboard Cite

We report the first observation of lasing topological edge states in a 1D Su-Schrieffer-Heeger active array of microring resonators. We show that the judicious use of non-Hermiticity can promote single edge-mode lasing in such arrays. Our experimental and theoretical results demonstrate that, in the presence of chiral-time symmetry, this non-Hermitian topological structure can experience phase transitions that are dictated by a complex geometric phase. Our work may pave the way towards understanding the fundamental aspects associated with the interplay among non-Hermiticity, nonlinearity, and topology in active systems.

show abstract

“…We revisit the Berry phase that may be accumulated along these loops, since it is an important indicator to distinguish whether the cone-like band follows the Dirac equation. The Berry phase in k -space for a non-Hermitian system is defined as [38] …”

Section: Topological Properties Of the Band With Triple Degeneracymentioning

confidence: 99%

Analytical study of mode degeneracy in non-Hermitian photonic crystals with TM-like polarization

Yin¹,

Liang²,

Wang³

et al. 2017

Phys. Rev. B

View full text Add to dashboard Cite

We present a study of the mode degeneracy in non-Hermitian photonic crystals (PC) with TMlike polarization and C4v symmetry from the perspective of the coupled-wave theory (CWT). The CWT framework is extended to include TE-TM coupling terms which are critical for modeling the accidental triple degeneracy within non-Hermitian PC systems. We derive the analytical form of the wave function and the condition of Dirac-like-cone dispersion when radiation loss is relatively small. We find that, similar to a real Dirac cone, the Dirac-like cone in non-Hermitian PCs possesses good linearity and isotropy, even with a ring of exceptional points (EPs) inevitably existing in the vicinity of the 2nd-order Γ point. However, the Berry phase remains zero at the Γ point, indicating the cone does not obey Dirac equation and is only a Dirac-like cone. The topological modal interchange phenomenon and non-zero Berry phase of the EPs are also discussed.

show abstract

Vorticity, gyroscopic precession, and spin-curvature force

Cited by 52 publications

References 52 publications

Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric

Relativistic sonic geometry for isothermal accretion in the Schwarzschild metric

Edge-Mode Lasing in 1D Topological Active Arrays

Analytical study of mode degeneracy in non-Hermitian photonic crystals with TM-like polarization

Contact Info

Product

Resources

About