Tootfinder

A Tale of Two Shocks
Robert F. Wimmer-Schweingruber, Domenico Trotta, Rungployphan Kieokaew, Liu Yang, Alexander Kollhoff, Lars Berger, Patrick K\"uhl, Stephan I. B\"ottcher, Bernd Heber, Philippe Louarn, Andrey Fedorov, Javier Rodriguez-Pacheco, Ra\'ul G\'omez-Herrero, Francisco Espinosa Lara, Ignacio Cernuda, Yulia Kartavykh, Linghua Wang, George C. Ho, Robert C. Allen, Glenn M. Mason, Zheyi Ding, Andrea Larosa, G. Sindhuja, Sandra Eldrum, Sebastian Fleth, David Lar…

A Tale of Two Shocks
It was the best of times, it was the worst of times, . . . - for the thermal/suprathermal particle populations in the vicinity of two traveling interplanetary shocks observed by Solar Orbiter on 2023-11-29 07:51:17 UTC and 2023-11-30 10:47:26 UTC at $\sim 0.83$ astronomical units from the Sun. We investigate these two very dissimilar shocks and elucidate their non-equilibrium features. We do not provide explanations of all observed features, our aim is to report them here for future reference…

Global Kinetic Simulations of Monster Shocks and Their Emission
Dominic Bernardi, Yajie Yuan, Alexander Y. Chen
https://arxiv.org/abs/2506.04175 https://…

Global Kinetic Simulations of Monster Shocks and Their Emission
Fast magnetosonic waves are one of the two low-frequency plasma modes that can exist in a neutron star magnetosphere. It was recently realized that these waves may become nonlinear within the magnetosphere and steepen into some of the strongest shocks in the universe. These shocks, when in the appropriate parameter regime, may emit GHz radiation in the form of precursor waves. We present the first global Particle-in-Cell simulations of the nonlinear steepening of fast magnetosonic waves in a di…

This https://arxiv.org/abs/2406.18322 has been replaced.
initial toot: https://mastoxiv.page/@…

A new quadrature for the generalized hydrodynamics equation and absence of shocks in the Lieb-Liniger model
In conventional fluids, it is well known that Euler-scale equations are plagued by ambiguities and instabilities. Smooth initial conditions may develop shocks, and weak solutions, such as for domain wall initial conditions (the paradigmatic Riemann problem of hydrodynamics), are not unique. The absence of shock formation experimentally observed in quasi-one-dimensional cold-atomic gases, which are described by the Lieb-Liniger model, provides perhaps the strongest pointer to a modification of t…

The Vlasov equation cannot fully account for collisionless shocks
Antoine Bret
https://arxiv.org/abs/2506.01548 https://arxiv.org/pdf…

The Vlasov equation cannot fully account for collisionless shocks
It is argued that the Vlasov equation cannot fully account for collisionless shocks since it conserves entropy, while a shock does not. A rigorous mathematical theory of collisionless shocks could require working at the Klimontovich level.

The Dynamics of Infall and Accretion Shocks in the Outer Disk
Susan Terebey, Loraine Sandoval Ascencio, Lizxandra Flores-Rivera, Neal Turner, Andrew Barajas
https://arxiv.org/abs/2505.24582

The Dynamics of Infall and Accretion Shocks in the Outer Disk
High-spatial-resolution observations of disks around young stars suggest planetary systems begin forming early, during the protostellar phase (< 1 Myr) when stars accrete most of their mass via infall from the surrounding cloud. During this era shocks are expected to be ubiquitous around the gaseous accretion disk due to supersonic infall that strikes the disk. We investigate the role of shocks using a theoretical and modeling framework we call the shock twist-angle Keplerian (STAK) disk, conne…

This https://arxiv.org/abs/2306.01511 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_qfi…

The Dynamic Persistence of Economic Shocks
We propose a novel framework for modeling time-varying persistence in economic time series, allowing for smoothly evolving heterogeneity in shock dynamics. We leverage localized regression techniques to flexibly identify changes in persistence over time, offering a data-driven alternative to traditional parametric models. We applied this methodology to U.S. inflation and stock market volatility data and found substantial persistence variations that align with key macroeconomic events and market…

This https://arxiv.org/abs/2411.02506 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Radially polarized synchrotron from galaxy-cluster virial shocks
Radio-to-$γ$-ray signals, recently found narrowly confined near the characteristic $2.4R_{500}$ scaled radii of galaxy clusters and groups, have been associated with their virial (structure-formation accretion) shocks based on spectro-spatial characteristics. By stacking high-latitude GMIMS radio data around MCXC galaxy clusters, we identify ($3σ$--$4σ$) excess radially polarized emission at the exact same scaled radius, providing directional support, and indicating tangential magnetic field…

A general relativistic hydrodynamic simulation code for studying advective, sub-Keplerian accretion flow onto black holes
Sudip K Garain
https://arxiv.org/abs/2506.01557

A general relativistic hydrodynamic simulation code for studying advective, sub-Keplerian accretion flow onto black holes
In this paper, we describe a general relativistic hydrodynamics simulation code which is developed to simulate advective accretion flow onto black holes. We are particularly interested in the accretion simulations of sub-Keplerian matter in the close vicinity of black holes. Due to the presence of centrifugal barrier, a nearly free-falling sub-Keplerian accretion flow slows down close to a black hole and can even pass through shocks before accelerating again to the black hole. We design our sim…

I've really enjoyed this miniseries on Houdini in case anyone is looking for something to listen to:
https://econtwitter.net/@TimHarford/114238312210225412

This https://arxiv.org/abs/2502.15084 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_eco…

Algorithmic Collusion under Observed Demand Shocks
The growing reliance on AI-driven pricing algorithms has raised antitrust concerns, particularly that third-party use of nonpublic competitor data may facilitate information sharing and undermine market competition. This paper examines a setting in which firms receive demand information from a common third party and incorporate it into their pricing algorithms. Specifically, I analyze the pricing behavior of Q-learning agents when demand shocks are observable. The simulation results show that a…

This https://arxiv.org/abs/2411.04869 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Modelling of the atomic lines' emission of fast moving pulsar nebulae
Bow shocks generated by pulsars moving through weakly ionized interstellar medium (ISM) produce emission dominated by non-equilibrium atomic transitions. These bow shocks are primarily observed as H$_α$ nebulae. We developed a package, named Shu, that calculates non-LTE intensity maps in more than 150 spectral lines, taking into account geometrical properties of the pulsars' motion and lines of sight. We argue here that atomic (CI, NI, OI) and ionic (SII, NII, OIII, NeIV) transitions can be us…

Minimising the numerical viscosity in Smoothed Particle Hydrodynamics simulations of discs
Cheng Chen, C. J. Nixon
https://arxiv.org/abs/2505.24343 https:/…

Minimising the numerical viscosity in Smoothed Particle Hydrodynamics simulations of discs
Simulations using the Smoothed Particle Hydrodynamics (SPH) technique typically include numerical viscosity to model shocks and maintain particle order on the kernel scale. This numerical viscosity is composed of linear and quadratic terms, with coefficients $α_{\rm SPH}$ and $β_{\rm SPH}$ respectively. Setting these coefficients too high results in excessive numerical dissipation, whereas setting them too low may lead to unwanted effects such as particle penetration, which also leads to exce…

Monetary policy, supply shocks, and retail energy prices https://www.sciencedirect.com/science/article/pii/S0140988325004220 @…

I've really enjoyed this miniseries on Houdini in case anyone is looking for something to listen to:
https://econtwitter.net/@TimHarford/114238312210225412

Plasma refilling of the lunar wake: plasma-vacuum interactions, electrostatic shocks, and electromagnetic instabilities
Xin An, Vassilis Angelopoulos, Terry Z Liu, Anton Artemyev, Andrew R. Poppe, Donglai Ma
https://arxiv.org/abs/2505.12497

Plasma refilling of the lunar wake: plasma-vacuum interactions, electrostatic shocks, and electromagnetic instabilities
A plasma void forms downstream of the Moon when the solar wind impacts the lunar surface. This void gradually refills as the solar wind passes by, forming the lunar wake. We investigate this refilling process using a fully kinetic particle-in-cell (PIC) simulation. The early stage of refilling follows plasma-vacuum interaction theory, characterized by exponential decay of plasma density into the wake, along with ion acceleration and cooling in the expansion direction. Our PIC simulation confirm…

This https://arxiv.org/abs/2411.03502 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_eco…

Adaptive Shock Compensation in the Multi-layer Network of Global Food Production and Trade
Global food production and trade networks are highly dynamic, especially in response to shortages when countries adjust their supply strategies. In this study, we examine adjustments across 123 agri-food products from 192 countries resulting in 23616 individual scenarios of food shortage, and calibrate a multi-layer network model to understand the propagation of the shocks. We analyze shock mitigation actions, such as increasing imports, boosting production, or substituting food items. Our find…

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