arXiv subjects

Shuo Song

Publications and source records attributed to Shuo Song.

3 recordsLinked to original sources

arXiv2026

Non-Gaussian hydrodynamic fluctuations in an expanding relativistic fluid

We consider non-equilibrium evolution of non-Gaussian fluctuations in a hydrodynamic system undergoing a boost-invariant expansion described by Bjorken flow. We derive the evolution equations for two- and three-point velocity correlators using the effective field theory framework and present analytical solutions for them. We show that the average Landau frame is better suited for studying non-Gaussian fluctuations of velocity when relativistic effects are important. In the Bjorken background, the average Landau frame corresponds to the density frame. We demonstrate that the three-point correlators depend nonlinearly on the non-equilibrium dynamics of the two-point functions, and exhibit non-trivial effects such as memory. The importance of these effects in the context of the search for the QCD critical point via fluctuations is discussed.

hep-th↗

arXiv2018

NY Vir Eclipse timing observations: Two planet solution

We report 18 new primary minima timing observations of the short-period eclipsing binary system NY Virginis. We combined these minima with previously published primary minima to update circumbinary exoplanet models in this system based on O-C timing variations. We performed a non-linear least-squares minimization search using a quadratic ephemeris and either one or two exoplanets. The only model with an acceptable fit includes a period derivative $\dot{P} = 2.83\times10^{-12}$ and two planets in eccentric orbits $e = 0.15,0.15$ with minimum masses 2.7 and 5.5 Jovian masses. Analysis of the orbit stability shows that this solution is stable for at least $10^8$ yr, but a small increase in eccentricity ($e\geq0.20$) for either planet renders the orbits unstable in less than $10^6$ years. A number of model parameters are significantly degenerate, so additional observations are required to determine planetary parameters with high statistical confidence.

astro-ph.EP↗

arXiv2017

Laser Streaming: Turning a Laser Beam into a Flow of Liquid

Transforming a laser beam into a mass flow has been a challenge both scientifically and technologically. Here we report the discovery of a new optofluidics principle and demonstrate the generation of a steady-state water flow by a pulsed laser beam through a glass window. In order to generate a flow or stream in the same path as the refracted laser beam in pure water from an arbitrary spot on the window, we first fill a glass cuvette with an aqueous solution of Au nanoparticles. A flow will emerge from the focused laser spot on the window after the laser is turned on for a few to tens of minutes, the flow remains after the colloidal solution is completely replaced by pure water. Microscopically, this transformation is made possible by an underlying plasmonic nanoparticle-decorated cavity which is self-fabricated on the glass by nanoparticle-assisted laser etching and exhibits size and shape uniquely tailored to the incident beam profile. Hydrophone signals indicate that the flow is driven via acoustic streaming by a long-lasting ultrasound wave that is resonantly generated by the laser and the cavity through the photoacoustic effect. The principle of this light-driven flow via ultrasound, i.e. photoacoustic streaming by coupling photoacoustics to acoustic streaming, is general and can be applied to any liquids, opening up new research and applications in optofluidics as well as traditional photoacoustics and acoustic streaming.

physics.flu-dyn↗