arXiv subjects

Runyu Meng

Publications and source records attributed to Runyu Meng.

4 recordsLinked to original sources

arXiv2026

WaveDM.jl: An Adaptable Simulation Framework for Dynamics of Baryonic and Wave Dark Matter on Galaxy Scales

We present WaveDM$.$jl, an open-source Julia package for high-performance simulations of wave dark matter dynamics on galaxy scales, with a design philosophy centered on extensibility and adaptability. The code solves the time-dependent Schrödinger--Poisson equation (SPE) using a pseudo-spectral Fourier method. The spectral solver is tightly integrated with N-body gravitational force solvers, enabling simultaneous evolution of wave dark matter and baryonic components in galaxy-scale simulations. WaveDM$.$jl unifies shared-memory, distributed-memory, and GPU execution within a multi-level parallelization framework, enabling the same computational workflow to scale from single-node to multi-node computing environments without requiring major code changes. To further facilitate user-friendly galaxy-scale simulations, the package provides a dedicated toolbox that integrates flexible initial condition generators, trajectory lookback, tidal force calculations, and real-time visualization. Beyond astrophysical applications, the code's modular architecture and general nonlinear Schrodinger framework enable cross-disciplinary studies such as nonlinear optics and cold-atom physics. The code is open source and available on https://github$.$com/JuliaAstroSim/WaveDM$.$jl.

astro-ph.GA↗

arXiv2026

Wave Cold Dark Matter Can Reproduce the Radial Acceleration Relation in X-ray Elliptical Galaxies

Wave cold dark matter (wave CDM) is a well-motivated variant within the collisionless CDM paradigm, in which the de~Broglie wavelengths of ultralight bosons become relevant on galactic scales. While many of the previous tests of wave CDM have focused on small-scale tensions involving solitonic cores and certain soliton--halo relations in galaxies, the radial acceleration relation (RAR) provides a complementary test: for a given baryonic mass distribution, it probes whether the DM halo can reproduce the observed total gravitational field. In this work we test wave CDM against the RAR using eight X-ray elliptical galaxies from the compilation of Lelli et al. We perform a suite of 3D Schrödinger--Poisson simulations and evolve the wave-CDM halos to virialized quasi-stationary states. For each galaxy and each adopted boson mass, we select the realization whose final snapshot most closely matches the empirical RAR. We find that the selected wave-CDM realizations for these elliptical galaxies can reproduce the RAR without including baryonic feedback or dark-matter self-interactions. At the boson mass $m_a=10^{-23}$eV, the combined fit to the eight galaxies gives $a_0=1.19\times10^{-10}\,\mathrm{m\,s^{-2}}$, consistent with the canonical value inferred from disk galaxies. When the boson mass is varied over $3\times 10^{-24}$ eV $\le m_a \le 2\times 10^{-23}$ eV, the best-fit value of $a_0$ changes by only $\sim 11\%$, and this variation shows no systematic trend with $m_a$. This insensitivity to boson mass arises because, over the radial range relevant for the RAR, the virialized halos are supported mainly by their velocity field, whereas the boson-mass-dependent quantum-pressure term is dynamically subdominant. These results show that wave CDM can reproduce the RAR in elliptical galaxies, and provide a new galactic-scale test of the model beyond the previous focus on solitonic cores.

astro-ph.GA↗

arXiv2025

A Promise for the JWST era: Massive black holes directly collapsed from wave dark matter haloes, and Star formation in and around their accretion flows

There are several puzzling phenomena from recent JWST observations, which seem to push the standard ΛCDM cosmology over the edge. All those puzzles can be understood in a coherent way if we assume that first massive black holes (MBHs, the "heavy eggs") formed by directly collapsing from wave CDM haloes, which can be even earlier than the formation of first galaxies (the "chickens"). We elucidate two false obstacles that have been believed to prevent wave CDM haloes from collapsing into black holes (namely "maximum stable mass" and "bosenova") and point out that general-relativistic instabilities (e.g., the non-axisymmetric instability numerically found in spinning scalar-field boson stars) could serve as the concrete mechanisms for direct-collapse black holes (DCBHs) born from wave dark matter. Once the MBHs formed, star formation bursts in and around the accretion flows, characteristic of a special mode in compact regions of high gravitational accelerations.

astro-ph.GA↗

arXiv2019

Complex Network Construction of Internet Financial risk

Internet finance is a new financial model that applies Internet technology to payment, capital borrowing and lending and transaction processing. In order to study the internal risks, this paper uses the Internet financial risk elements as the network node to construct the complex network of Internet financial risk system. Different from the study of macroeconomic shocks and financial institution data, this paper mainly adopts the perspective of complex system to analyze the systematic risk of Internet finance. By dividing the entire financial system into Internet financial subnet, regulatory subnet and traditional financial subnet, the paper discusses the relationship between contagion and contagion among different risk factors, and concludes that risks are transmitted externally through the internal circulation of Internet finance, thus discovering potential hidden dangers of systemic risks. The results show that the nodes around the center of the whole system are the main objects of financial risk contagion in the Internet financial network. In addition, macro-prudential regulation plays a decisive role in the control of the Internet financial system, and points out the reasons why the current regulatory measures are still limited. This paper summarizes a research model which is still in its infancy, hoping to open up new prospects and directions for us to understand the cascading behaviors of Internet financial risks.

econ.EM↗