Quasi-normal modes (QNMs) uniquely describe the gravitational-wave ringdown of post-merger black holes. While linear QNM regime has been extensively studied, recent work highlighted importance second-perturbative-order, quadratic QNMs (QQNMs) arising from nonlinear coupling QNMs. Previous attempts to quantify magnitude these QQNMs have shown discrepant results. Using a new hyperboloidal framework, we resolve discrepancy by showing that QQNM/QNM ratio is function not only hole parameters but...

Quasinormal modes (QNMs) uniquely describe the dominant piece of gravitational-wave ringdown postmerger black holes. While linear QNM regime has been extensively studied, recent work highlighted importance second-perturbative-order, quadratic QNMs (QQNMs) arising from nonlinear coupling QNMs. Previous attempts to quantify magnitude these QQNMs have shown discrepant results. Using a new hyperboloidal framework, we resolve discrepancy by showing that QQNM/QNM ratio is function not only hole...

Postadiabatic models of extreme- and intermediate-mass-ratio inspirals will require calculations second-order gravitational self-force effects in the spacetime a spinning, Kerr black hole. We take step toward such by implementing recently formulated Teukolsky puncture scheme with Green-Hollands-Zimmerman metric reconstruction [Classical Quantum Gravity 39, 015019 (2022)]. This eliminates critical obstacle gauge singularities that arise standard ``no-string'' reconstruction. Our first...

Abstract Kinetic Hydrate Inhibitors (KHIs) are one of the two types Low Dose (LDHIs) which more and used for gas hydrate control in oil industry, offering significant CAPEX advantages over traditional thermodynamic inhibitors (e.g. methanol, glycols). As KHIs traditionally considered "nucleation inhibitors", their lab evaluation is generally undertaken by measurement an "induction" or "hold" time before hydrates start effectively to form. However, as nucleation stochastic nature, obtaining...

Abstract Replacement of the traditional thermodynamic hydrate inhibitors (methanol and glycols) in wet gas applications is more highly desirable for cost savings Health, Safety & Environment (HSE) considerations. This seems achievable by using alternative Kinetic Hydrate Inhibitors (KHI). KHIs are able to delay formation time needed transport effluents region conditions. The KHI efficiency generally based both on subcooling that can be matched inhibitor provide. Within frame various...

Cataldo has found all rigidly rotating self-gravitating perfect fluid solutions in $2+1$ dimensions with a negative cosmological constant $\mathrm{\ensuremath{\Lambda}}$, for density that is specified priori as function of certain radial coordinate. We rewrite these standard polar-radial coordinates, an arbitrary barotropic equation state $p(\ensuremath{\rho})$. For any given state, we find the two-parameter family regular center and finite total mass $M$ angular momentum $J$ (rigidly...

Four components of the axisymmetric Einstein equations in 2+1 dimensions with negative cosmological constant can be written as $\nabla_aM=\dots$ and $\nabla_aJ=\dots$, where dots stand for stress-energy terms, $M$ $J$ are scalars. In vacuum, they reduce to mass angular momentum parameters BTZ solution same name. The integrability conditions give rise two conserved currents $\nabla_aj^a_{(M)}=0$ $\nabla_aj^a_{(J)}=0$. current is just Noether due axisymmetry, but unexpected presence rotation....

Post-adiabatic models of extreme- and intermediate-mass-ratio inspirals will require calculations second-order gravitational self-force effects in the spacetime a spinning, Kerr black hole. We take step toward such by implementing recently formulated Teukolsky puncture scheme with Green-Hollands-Zimmerman metric reconstruction [CQG 39, 015019 (2022)]. This eliminates critical obstacle gauge singularities that arise standard no-string reconstruction. Our first proof-of-principle...

Most self-force calculations rely, in one way or another, on representations of a particle's Detweiler- Whiting singular field. We present simple method calculating the field to high order local expansion powers distance from particle. As demonstration, we compute 14th distance, 10 orders beyond previous state art, case scalar charge circular orbit around Schwarzschild black hole. provide result both 4-dimensional form and decomposed suitable for use an m-mode puncture scheme. Our should...

Second-order self-force calculations will be critical for modelling extreme-mass-ratio inspirals, and they are now known to have high accuracy even binaries with mass ratios $\sim 1:10$. Many of the challenges facing these related slow convergence spherical-harmonic (or spheroidal harmonic) mode sums in a region containing small companion. In this paper, we begin develop multi-domain framework that can evade those problems. Building on recent work by Osburn Nishimura, problematic spacetime...

We carry out numerical simulations of the gravitational collapse a perfect fluid with ultrarelativistic equation state $P=\ensuremath{\kappa}\ensuremath{\rho}$, in spherical symmetry $2+1$ spacetime dimensions $\mathrm{\ensuremath{\Lambda}}<0$. At threshold prompt collapse, we find type II critical phenomena (apparent horizon mass and maximum curvature scale as powers distance from threshold) for $\ensuremath{\kappa}\ensuremath{\gtrsim}0.43$, I (lifetime scales logarithm...

We carry out numerical simulations of the gravitational collapse a rotating perfect fluid with ultrarelativistic equation state $P=\kappa\rho$, in axisymmetry $2+1$ spacetime dimensions $\Lambda<0$. show that for $\kappa \lesssim 0.42$, critical phenomena are type I and solution is stationary. The picture \gtrsim 0.43$ more delicate: small angular momenta, we find II quasistationary, contracting adiabatically. spin-to-mass ratio increases as it contracts, hence so does black hole created at...