Shock Instability Research Articles

Endovascular treatment for 2 types of subclavian artery injury: A case report.

Subclavian artery (SCA) injuries, though rare, carry significant morbidity and mortality risks due to significant blood loss causing hypovolemic shock. Early diagnosis and adequate treatment are crucial to minimize bleeding and associated morbidity. Recent advances in endovascular techniques offer faster and more accurate treatment options compared to traditional open surgical repair. This study demonstrates the efficacy of endovascular treatment in 2 cases of SCA injury and reviews its indications, limitations, and precautions. A 69-year-old man presented with a penetrating SCA injury from a steel bar, and a 38-year-old woman presented with a blunt SCA injury caused by a fall. Both patients were hemodynamically unstable upon presentation. Both patients were diagnosed with SCA injuries. The man had a penetrating injury, while the woman had a blunt injury, both resulting in hemodynamic instability and significant risk of hypovolemic shock. Endovascular techniques, including the use of covered stent grafts, were employed to manage the injuries. These techniques allowed for rapid and efficient treatment, reducing the need for open surgical intervention. Both patients were successfully treated using endovascular methods and were discharged without any complications. The endovascular approach minimized blood loss, transfusion needs, and hospital stay. This study demonstrates the effectiveness of endovascular techniques in rapidly diagnosing, bridging, and definitively treating SCA injuries, suggesting their use as a first-line therapy.

Numerical stability analysis of Godunov-type schemes for high Mach number flow simulations

Modern shock-capturing schemes often suffer from numerical shock instabilities when simulating strong shocks, limiting their application in supersonic or hypersonic flow simulations. In the current study, we devote our efforts to investigating the shock instability problem for second-order schemes, which has not gotten enough attention in previous research but is crucial to address. To this end, we develop the matrix stability analysis method for the finite-volume Monotone Upstream-centered Schemes for Conservation Laws (MUSCL) approach, taking into account the influence of reconstruction. With the help of this newly developed method, the shock instability of second-order schemes is investigated quantitatively and efficiently. The results demonstrate that when second-order schemes are employed, whether shock instabilities will occur is closely related to the property of Riemann solvers, just like the first-order case. However, enhancing spatial accuracy still impacts the shock instability problem, and the impact can be categorized into two types depending on the dissipation of Riemann solvers. Furthermore, the research emphasizes the impact of the numerical shock structure, highlighting both its role as the source of instability and the influence of its state on the occurrence of instability. One of the most significant contributions of this study is the confirmation of the multidimensional coupled nature of shock instability. Both one-dimensional and multidimensional instabilities are proven to influence the instability problem, and they have different properties. Moreover, this paper reveals that increasing the aspect ratio and distortion angle of the computational grid can help mitigate shock instabilities. The current work provides an effective tool for quantitatively investigating the shock instabilities for second-order schemes, revealing the inherent mechanism and thereby contributing to the elimination of shock instability.

Referral and outcomes of mechanical thrombectomy for pulmonary embolism - a single-centre experience

Abstract Funding Acknowledgements None. Introduction Acute pulmonary embolism (PE) is a significant cause of morbidity and mortality, and percutaneous catheter-based treatments have emerged as an effective treatment option alongside thrombolysis. However, data concerning long-term outcomes are scarce. Methods All patients referred to a tertiary centre for pulmonary angiography with the intent to perform mechanical thrombectomy in the context of acute PE between January 2016 and August 2023 were retrospectively included and clinical data and outcomes were collected. Results Fifty-two patients (58% female; mean age 66±18 years) were referred to pulmonary angiography in the setting of acute PE, of whom 40 patients (77%) underwent continuous aspiration mechanical thrombectomy with an overall success rate of 70%. Twenty-eight percent of patients had bilateral thrombus. Thirty-two patients had intermediate-high risk or high-risk PE, and the mean Pulmonary Embolism Severity Index (PESI) was 146 points. Thirteen patients (25%) underwent thrombolysis prior to angiography, while 15 patients (28%) had an absolute or relative contraindication for thrombolysis. Ventilation/perfusion scans were performed in ten patients (19%) during the follow-up period, of whom five patients (10%) had evidence of residual illness, with no significant differences between the thrombectomy and non-thrombectomy groups (p=0.8). The overall mortality rate over the complete follow-up period was 39%, while 25% of patients died within 48 hours of the procedure. Predictors of mortality on univariate analysis included older age (HR 1.06 [95% CI 1.00-1.11, p = 0.03]), history of chronic obstructive pulmonary disease (HR 3.88 [95% CI 1.41-10.69, p = 0.01]), history of previous deep vein thrombosis or PE (HR 3.40 [95% CI 1.34-8.63, p = 0.01]), thrombolysis prior to referral for mechanical thrombectomy (HR 5.94 [95% CI 1.93-18.26, p <0.01), shock or haemodynamic instability (HR 8.50 [95% CI 2.44-29,52, p <0.01]) and resuscitated cardiac arrest (HR 5.98 [95% CI 2.34-15.30, p <0.01]). On Cox multivariate analysis, the presence of shock or haemodynamic instability was a predictor of increased mortality (HR 5.23 [95% CI 1.12-24.3, p = 0.04]). Conclusions Intermediate and high risk acute PE is a clinical entity with a high morbidity and mortality rate regardless of treatment strategy, particularly during the index hospitalization and in patients with shock or haemodynamic instability.

Quasi all-speed schemes for magnetohydrodynamic flows in a wide range of Mach numbers

We present novel numerical schemes for ideal magnetohydrodynamic (MHD) simulations aimed at enhancing stability against numerical shock instability and improving the accuracy of low-speed flows in multidimensions. Stringent benchmark tests confirm that our scheme is more robust against numerical shock instability and is more accurate for low-speed, nearly incompressible flows than conventional shock-capturing schemes. Our scheme is a promising tool for tackling MHD systems, including both high and low Mach number flows.

Version [1.1]—[MSAT: Matrix stability analysis tool for shock-capturing schemes]

The numerical shock instability problem significantly limits the application of the finite volume method in hypersonic flow simulations, especially for high-order schemes, which will encounter more severe shock instability problems. In the previous work, the MSAT (matrix stability analysis tool) was introduced to quantitatively analyze the numerical shock instability problem. However, the utilization of the three-point reconstruction stencil in the original version of MSAT presents challenges in conducting investigations into high-order schemes. The current work provides an extension of MSAT by extending the reconstruction stencil to five points, a challenging but necessary endeavor for high-order schemes. This extension enables MSAT to provide analyses for schemes with high-order reconstruction methods. Furthermore, the updated MSAT can be utilized to investigate the impact of characteristic variable reconstruction on the shock instability problem. Results demonstrate the reliability of the updated MSAT and reveal novel characteristics in the shock instability of high-order schemes. Consequently, the updated MSAT will contribute to the investigation of shock instabilities for high-order schemes, ultimately aiding in mitigating this challenging problem.

Intensive Care Treatment of Pulmonary Embolism: An Update Based on the Revised AWMF S2k Guideline.

Acute pulmonary embolism (PE) remains a significant cause of morbidity and requires prompt diagnosis and management. The prognosis of affected patients depends on the clinical severity. Therefore, risk stratification is imperative for therapeutic decision-making. Patients with high-risk PE need intensive care. These include patients who have successfully survived resuscitation, with obstructive shock or persistent haemodynamic instability. Bedside diagnostics by means of sonographic procedures are of outstanding importance in this high-risk population. In addition to the treatment of hypoxaemia with noninvasive and invasive techniques, the focus is on drug-based haemodynamic stabilisation and usually requires the elimination or reduction of pulmonary vascular thrombotic obstruction by thrombolysis. In the event of a contraindication to thrombolysis or failure of thrombolysis, various catheter-based procedures for thrombus extraction and local thrombolysis are available today and represent an increasing alternative to surgical embolectomy. Mechanical circulatory support systems can bridge the gap between circulatory arrest or refractory shock and definitive stabilisation but are reserved for centres with the appropriate expertise. Therapeutic strategies for patients with intermediate- to high-risk PE in terms of reduced-dose thrombolytic therapy or catheter-based procedures need to be further evaluated in prospective clinical trials.

Robust and accurate Roe-type Riemann solver with compact stencil: Rotated-RoeM scheme

In this study, we aim to develop a robust and accurate Riemann solver to resolve strong shock waves with compact stencil information by applying the rotated hybrid concept to the RoeM scheme. The original RoeM scheme offers good robustness from the perspective of avoiding shock instability, also called the carbuncle phenomenon, in hypersonic flows by introducing Mach-number-based functions. These functions rely on multi-dimensional shock discontinuity sensing terms to capture grid-aligned shock waves, thus necessitating sharing of values of cells adjacent to each vertex. Consequently, constructing a data structure that can handle such a wide stencil is necessary, particularly for implementations on unstructured grids. Moreover, communication of this stencil information on parallel computation can increase computational costs.To overcome these complexities, the rotated hybrid concept is applied to the RoeM scheme, to replace the multi-dimensional terms while still resolving the grid-aligned shock instability. In addition, a Mach-number-based weighting function is introduced to distinguish between the flow around the boundary layer and the onset of shock instability. The damping characteristic of the proposed scheme is compared to that of the original RoeM scheme by conducting a linear perturbation analysis. The findings reveal that the proposed scheme effectively controls spurious oscillations across strong shock waves. Numerous test cases are presented to demonstrate the robustness and accuracy of the proposed approach. Notably, the proposed scheme successfully resolves thermal boundary layers and accurately predicts the heat transfer rate around stagnation points in hypersonic flows.

A Parametric Study of the SASI Comparing General Relativistic and Nonrelativistic Treatments* * Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or

We present numerical results from a parameter study of the standing accretion shock instability (SASI), investigating the impact of general relativity (GR) on the dynamics. Using GR hydrodynamics with GR gravity, and nonrelativistic (NR) hydrodynamics with Newtonian gravity, in an idealized model setting, we vary the initial radius of the shock, and by varying its mass and radius in concert, the proto-neutron star compactness. We investigate four compactnesses expected in a post-bounce core-collapse supernova (CCSN). We find that GR leads to a longer SASI oscillation period, with ratios between the GR and NR cases as large as 1.29 for the highest-compactness suite. We also find that GR leads to a slower SASI growth rate, with ratios between the GR and NR cases as low as 0.47 for the highest-compactness suite. We discuss implications of our results for CCSN simulations.

Growth of Massive Molecular Cloud Filament by Accretion Flows. I. Slow-shock Instability versus Ambipolar Diffusion

The Herschel Gould Belt Survey showed that stars form in dense filaments in nearby molecular clouds. Recent studies suggest that massive filaments are bound by the slow shocks caused by accretion flows onto the filaments. The slow shocks are known to be unstable to corrugation deformation of the shock front. Corrugation instability could convert the accretion flow's ram pressure into turbulent pressure that influences the width of the filament, which, according to theory, determines the self-gravitational fragmentation scale and core mass. In spite of its importance, the effect of slow-shock instability on star-forming filaments has not been investigated. In addition, the linear dispersion relation obtained from ideal magnetohydrodynamics (MHD) analysis shows that the most unstable wavelength of shock corrugation is infinitesimally small. In the scale of dense filaments, the effect of ambipolar diffusion can suppress the instability at small scales. This study investigates the influence of ambipolar diffusion on the instability of the slow shock. We perform two-dimensional MHD simulations to examine the linear growth of the slow-shock instability, considering the effect of ambipolar diffusion. The results demonstrate that the most unstable scale of slow-shock instability is approximately 5 times the length scale of ambipolar diffusion ℓ AD calculated using post-shock variables, where ℓ AD corresponds to the scale where the magnetic Reynolds number for ambipolar diffusivity is unity.

Abstract 16273: Contemporary Risk Prediction Model for In-Hospital or 30-day Mortality After Percutaneous Coronary Interventions: An NCDR CathPCI Registry Model

Introduction: While the ACC NCDR CathPCI registry has long provided risk-adjusted benchmarking of in-hospital mortality after percutaneous coronary intervention (PCI), extending follow-up to 30 days in those who are discharged can provide a more comprehensive assessment of post-PCI outcomes. Aims: We sought to develop a new model for predicting in-hospital or 30-day mortality after PCI with excellent discrimination to be used for quality improvement efforts. Methods: Data from 472,594 PCIs performed in 2019 at 1,369 sites from the CathPCI registry linked to National Death Index data were used to identify pre-procedural and angiographic predictors of mortality and develop a predictive model of in-hospital or 30-day mortality. A thousand bootstrapped samples of the development cohort were created, and stepwise logistic regression was performed on each sample. The final model included variables that were selected in at least 70% of the bootstrapped samples. Results: The overall in-hospital or 30-day mortality rate after PCI in the entire cohort was 2.8%. In those undergoing elective PCI without shock or clinical instability, mortality was 0.5%, while in those undergoing salvage PCI or for refractory shock it was 60.3% . Cardiovascular instability, level of consciousness after cardiac arrest, frailty, and chronic kidney disease stage were the factors most predictive of mortality (Table 1). The full model performed well with good discrimination in the overall population (C-index= 0.907), and in the cohorts of patients with STEMI (c-index=0.899), and cardiac arrest or shock (c-index=0.828), as well as across the spectrum of procedural risk. Conclusions: This risk model can accurately predict in-hospital or 30-day mortality in those undergoing PCI by incorporating variables that capture cardiovascular instability and clinical status. Extending the mortality follow-up period should enable for a more standardized evaluation of outcomes across hospitals.

A shock-stable numerical scheme accurate for contact discontinuities: Applications to 3D compressible flows

The low-dissipation Roe scheme is a popular shock capturing scheme but the shock instability, such as the infamous carbuncle phenomenon, seriously affects its application in high Mach number flows. Although considerable research has been undertaken in two dimensions, mechanism analysis of the three-dimensional shock instability is relatively scarce. Numerical simulations of the Sedov blast wave indicate that the shock instability is more prominent in three dimensions, so it has theoretical and practical significance to analyze and heal the numerical instability. The mechanism for three-dimensional shock instability has been thoroughly studied by means of the linearized stability analysis and the dissipation-controlling approach which introduces the required transverse dissipation in the numerical shock layer and is adopted to enhance the Roe scheme’s shock stability. Furthermore, the unphysical expansion shock resulting from the violation of entropy condition is eliminated by a simple modification of numerical signal speed. For the improvement of the resolution for contact discontinuities and shear waves, an algebraic method which combines the THINC reconstruction scheme and the BVD algorithm is employed to minimize the density difference in the numerical diffusion term. A series of benchmark numerical experiments fully demonstrate that the proposed scheme is endowed with excellent robustness against the shock instability and high accuracy for contact discontinuities and shear waves.

An Adaptive Mesh Refinement–Rotated Lattice Boltzmann Flux Solver for Numerical Simulation of Two and Three-Dimensional Compressible Flows with Complex Shock Structures

An adaptive mesh refinement–rotated lattice Boltzmann flux solver (AMR-RLBFS) is presented to simulate two and three-dimensional compressible flows with complex shock structures. In the method, the RLBFS, which has a strong shock-capturing capability and can effectively eliminate the shock instability phenomenon, is applied to solve the flow filed by reconstructing the fluxes at each cell interface adaptively with the mesoscopic lattice Boltzmann model. To locally and dynamically improve the resolution of intricate shock structures and optimize the required computational resources, a block-structured adaptive mesh refinement (AMR) technique is introduced. The validity and effectiveness of the proposed method are confirmed through a range of two and three-dimensional numerical cases, including the shock tube problem, the four-wave Riemann problem, explosion within a rectangular box, and the vorticity induced by a shock. The results obtained using the AMR-RLBFS exhibit excellent agreement with published data and demonstrate high accuracy in capturing complex shock structures. The computational efficiency of the AMR-RLBFS can be also improved significantly compared to the RLBFS on uniform grids. Furthermore, the numerical outcomes underscore the capability of the AMR-RLBFS to eliminate shock instability effects while efficiently capturing a broader spectrum of small-scale vertical structures. These findings highlight the ability of AMR-RLBFS to improve the computational efficiency and capture intricate shock structures effectively, making it a valuable tool for studying a wide range of compressible flows from aerodynamics to astrophysics.

A simple HLLE-type scheme for all Mach number flows

A simple HLLE-type scheme is proposed for all Mach number flows. In the proposed scheme, no extra wave structure is added in the HLLE scheme to resolve the shear wave while the contact wave is resolved by adding a wave structure similar to the HLLEM scheme. The resolution of the shear layers and the flow features at low Mach numbers is achieved by a velocity reconstruction method based on the face normal Mach number. Robustness against the numerical instabilities is achieved by scaling the velocity reconstruction function in the vicinity of shock with a multi-dimensional pressure sensor. The ability of the proposed scheme to resolve low Mach flow features is demonstrated through asymptotic analysis while the stability of the proposed scheme for strong shock is demonstrated through linear perturbation and matrix stability analyses. A set of numerical test cases are solved to show that the proposed scheme is free from numerical shock instability problems at high speeds and is capable of resolving the flow features at very low Mach numbers.

Obstructive Shock Pulmonary Embolism: Catheter Directed Thrombolysis

Venous thromboembolism is one of the most frequently encountered condition for which patients need intensive care admission often. Most of the time patients presents with shock and hemodynamic instability if it is massive pulmonary embolism. Incidence of Vte is comparable to western population in India, studies conducted by Ayyapan et all say it around 20/10,000 admission. Studies showed higher mortality of around 50% in high risk (massive) and mortality of around 14% in intermediate risk (sub-massive) PE which necessitating more aggressive approach in high-risk groups. Rapid administration of systemic thrombolytic agents is indicated in massive pulmonary embolism patients who presents with hemodynamic instability but systemic thrombolytic therapy is associated with risk of major bleeding around 20% and haemorrhagic stroke of 2% to 5% . During systemic thrombolysis shunting of thrombolytic agents away from clot into the systemic circulation which makes it failed lysis sometimes along with major bleeding.

One in four patients with gastrointestinal bleeding develops shock or hemodynamic instability: A systematic review and meta-analysis.

Hemodynamic instability and shock are associated with untoward outcomes in gastrointestinal bleeding. However, there are no studies in the existing literature on the proportion of patients who developed these outcomes after gastrointestinal bleeding. To determine the pooled event rates in the available literature and specify them based on the bleeding source. The protocol was registered on PROSPERO in advance (CRD42021283258). A systematic search was performed in three databases (PubMed, EMBASE, and CENTRAL) on 14th October 2021. Pooled proportions with 95%CI were calculated with a random-effects model. A subgroup analysis was carried out based on the time of assessment (on admission or during hospital stay). Heterogeneity was assessed by Higgins and Thompson's I2 statistics. The Joanna Briggs Institute Prevalence Critical Appraisal Tool was used for the risk of bias assessment. The Reference Citation Analysis (https://www.referencecitationanalysis.com/) tool was applied to obtain the latest highlight articles. We identified 11589 records, of which 220 studies were eligible for data extraction. The overall proportion of shock and hemodynamic instability in general gastrointestinal bleeding patients was 0.25 (95%CI: 0.17-0.36, I2 = 100%). In non-variceal bleeding, the proportion was 0.22 (95%CI: 0.14-0.31, I2 = 100%), whereas it was 0.25 (95%CI: 0.19-0.32, I2 = 100%) in variceal bleeding. The proportion of patients with colonic diverticular bleeding who developed shock or hemodynamic instability was 0.12 (95%CI: 0.06-0.22, I2 = 90%). The risk of bias was low, and heterogeneity was high in all analyses. One in five, one in four, and one in eight patients develops shock or hemodynamic instability on admission or during hospitalization in the case of non-variceal, variceal, and colonic diverticular bleeding, respectively.

Aborted living-donor liver transplantation in the real-world setting, lessons from 13 937 cases of Vanguard Multi-center Study of International Living Donor Liver Transplantation Group

There are exceedingly uncommon but clearly defined situations where intraoperative abortions are inevitable in living-donor liver transplantation (LDLT). This study aimed to summarize the cases of aborted LDLT and propose a strategy to prevent abortion or minimize donor damage from both recipient and donor sides. We collected data from a total of 43 cases of aborted LDLT out of 13 937 cases from 7 high-volume hospitals in the Vanguard Multi-center Study of the International Living Donor Liver Transplantation Group and reviewed it retrospectively. Of the 43 cases, there were 24 recipient-related abortion cases and 19 donor-related cases. Recipient-related abortions included pulmonary hypertension (n = 8), hemodynamic instability (n = 6), advanced hepatocellular carcinoma (n = 5), bowel necrosis (n = 4), and severe adhesion (n = 1). Donor-related abortions included graft steatosis (n = 7), graft fibrosis (n = 5), primary biliary cholangitis (n = 3), anaphylactic shock (n = 2), and hemodynamic instability (n = 2). Total incidence of aborted LDLT was 0.31%, and there was no remarkable difference between the centers. A strategy to minimize additional donor damage by delaying the donor’s laparotomy or trying to open the recipient’s abdomen with a small incision should be effective in preventing some causes of aborted LDLT, such as pulmonary hypertension, advanced cancer, and severe adhesions.

Effect of stellar rotation on the development of post-shock instabilities during core-collapse supernovae

Context. The growth of hydrodynamical instabilities is key to triggering a core-collapse supernova explosion during the phase of stalled accretion shock, immediately after the birth of a proto-neutron star (PNS). Stellar rotation is known to affect the standing accretion shock instability (SASI) even for small rotation rates, but its effect on the onset of neutrino-driven convection is still poorly known. Aims. We assess the effect of stellar rotation on SASI when neutrino heating is taken into account as well as the effect of rotation on neutrino-driven convection. The interplay of rotation with these two instabilities affects the frequency of the mode m = 2, which can be detected with gravitational waves at the onset of a supernova explosion. Methods. We used a linear stability analysis to study the dynamics of the accreting gas in the equatorial plane between the surface of the PNS and the stationary shock. We explored rotation effects on the relative strength of SASI and convection by considering a large range of specific angular momenta and neutrino luminosities. Results. The nature of the dominant non-axisymmetric instability developing in the equatorial post-shock region depends on both the convection parameter, χ, and the rotation rate. Equatorial convective modes with χ ≳ 5 are hampered by differential rotation. At smaller χ, however, mixed SASI-convective modes with a large angular scale, m = 1, 2, 3, can take advantage of rotation and become dominant for relatively low rotation rates, at which centrifugal effects are small. For rotation rates exceeding ∼30% of the Keplerian rotation at the PNS surface, a new instability regime is characterised by a frequency that, when measured in units of the post-shock velocity and radius, vsh/rsh, is nearly independent of the convection parameter, χ. A strong prograde m = 2 spiral dominates over a large parameter range and is favorable to the production of gravitational waves. In this regime, a simple linear relation exists between the oscillation frequency of the dominant mode and the specific angular momentum of the accreted gas. Conclusions. Three different regimes of post-shock instabilities can be distinguished depending on the rotation rate. For low rotation rates (less than 10% of the Keplerian rotation at the PNS surface), differential rotation has a linear destabilising effect on SASI and a quadratic stabilising or destabilising effect on the purely convective equatorial modes depending on their azimuthal wavenumber. Intermediate rotation rates (10% to 30% of the Keplerian rotation) lead to the emergence of mixed SASI-convection-rotation modes that involve large angular scales. Finally, strong rotation erases the influence of the buoyancy and heating rate on the instability. This independence allows for a reduction in the parameter space, which can be helpful for gravitational wave analysis.

Accurate and Robust Hybrid HLLC Riemann Solver on Triangular Grids

The HLLC scheme is an accurate, approximate Riemann solver. However, it suffers from the carbuncle phenomenon and numerical shock instability problems on both rectangular and triangular grids. In this paper, a hybrid HLLC scheme () is developed by adding some extra computations to the original HLLC scheme in order to achieve a stable and accurate scheme. The idea of the hybrid scheme is straightforward as it uses a simple shock-capturing function with parameter to detect regions where pressure oscillations such as shock waves are significant. In these regions, a less diffusive version of the scheme () is activated with a new weighting function with parameter . This new weighting function is designed to control the stability and accuracy of the hybrid scheme via the ratio of the square of the speed of sound of two adjacent cells. A linear perturbation analysis of an odd–even decoupling problem is used to analyze the effectiveness of the proposed hybrid scheme in damping perturbations. Several numerical examples are given to demonstrate that the new scheme () can obtain accurate solutions and that it is simple and efficient and requires comparable computational time with the original scheme.

Characterizing a supernova’s standing accretion shock instability with neutrinos and gravitational waves

We perform a novel multimessenger analysis for the identification and parameter estimation of the standing accretion shock instability (SASI) in a core-collapse supernova with neutrino and gravitational-wave (GW) signals. In the neutrino channel, this method performs a likelihood ratio test for the presence of SASI in the frequency domain. For gravitational-wave signals we process an event with a modified constrained likelihood method. Using simulated supernova signals, the properties of the Hyper-Kamiokande neutrino detector, and O3 LIGO interferometric data, we produce the two-dimensional probability density function (PDF) of the SASI activity indicator and calculate the probability of detection PD as well as the false identification probability PFI. We discuss the probability to establish the presence of the SASI as a function of the source distance in each observational channel, as well as jointly. Compared to a single-messenger approach, the joint analysis results in a PD (at PFI=0.1) of SASI activities that is larger by up to ≈40% for a distance to the supernova of 5 kpc. We also discuss how accurately the frequency and duration of the SASI activity can be estimated in each channel separately. Our methodology is suitable for implementation in a realistic data analysis and a multimessenger setting.8 MoreReceived 24 November 2022Accepted 24 February 2023DOI:https://doi.org/10.1103/PhysRevD.107.083017© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasExtrasolar neutrino astronomyGravitational wavesNovae & supernovaeTechniquesGravitational wave detectionGravitational wave detectorsNeutrino detectorsGravitation, Cosmology & Astrophysics

Standing accretion shock instability in the collapse of a rotating stellar core

Hydrodynamical instabilities, such as the standing accretion shock instability (SASI), play an essential role in the dynamics of core-collapse supernovae, with observable imprints in the neutrino and gravitational wave signals. Yet, the impact of stellar rotation on the development of SASI is poorly explored. We investigate the conditions favoring the growth of SASI in the presence of rotation through a perturbative analysis. The properties of SASI are compared in two stationary configurations, cylindrical and spherical equatorial, which mainly differ by their advection timescales from the shock to the proto-neutron star surface. Without rotation, the mode $m=1$, corresponding to a one-armed spiral SASI deformation, can be significantly more unstable in the spherical equatorial configuration. In fact, the shorter advection time in the spherical equatorial geometry allows for a larger contribution of the entropic-acoustic coupling from the region of adiabatic compression near the surface of the proto-neutron star. The angular momentum of the collapsing core favors the growth of prograde spiral modes $m=1$ and $m=2$ in both geometries. Although the growth rate of the spiral instability is systematically faster in spherical geometry, its oscillation frequency is remarkably insensitive to the geometry. Such a contrast with nonrotating flows calls for a deeper understanding of the role of advection in the mechanism of spiral SASI. Our findings suggest that the resonant coupling of acoustic waves with their corotation radius may play a major role in the instability mechanism of collapsing cores with rotation. Elucidating this physical mechanism is essential to interpret the signal from future multimessenger supernova observations.