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Men-Quan Liu

Publications and source records attributed to Men-Quan Liu.

5 recordsLinked to original sources
arXiv2026

Periodic Radio Technosignature Search toward 3I/ATLAS with FAST

3I/ATLAS, the third confirmed interstellar object discovered in the Solar System, provides a unique opportunity for targeted technosignature searches. We report a periodic radio technosignature search toward 3I/ATLAS using the Five-hundred-meter Aperture Spherical Telescope (FAST) L-band multibeam receiver. To search for periodically modulated signals and distinguish center-beam-dominated candidates from multibeam radio-frequency interference, we apply canonical polyadic decomposition (CPD) to the multibeam dynamic spectra. CPD factorizes the multibeam data tensor into a set of separable components, with associated time, frequency, and beam signatures. Candidate components are then selected through periodogram and autocorrelation diagnostics. We find no credible artificial periodic radio technosignature above 0.146 W is detected from the direction of 3I/ATLAS. This search expands the range of signal types explored for this target by including periodic modulated signal, and illustrates that CPD is a promising framework for multibeam periodic technosignature searches.

astro-ph.IM↗
arXiv2012

Dynamics of neutrino-driven winds: inclusion of accurate weak interaction rates in strong magnetic fields

Solving Newtonian steady-state wind equations with accurate weak interaction rates and magnetic fields (MFs) of young neutron stars considered, we study the dynamics and nucleosynthesis of neutrino-driven winds (NDWs) from proto neutron stars (PNSs). For a typical 1.4 M$_{\odot}$ PNS model, we find the nucleosynthesis products are closely related to the luminosity of neutrinos and anti-neutrinos. The lower the luminosity is, the larger effect to the NDWs caused by weak interactions and MFs is. At a high anti-neutrino luminosity of typically $8\times 10^{51}$ erg s$^{-1}$, neutrinos and anti-neutrinos dominate the processes in a NDW and the MFs hardly change the wind's properties. While at a low anti-neutrino luminosity of $10^{51}$ erg s$^{-1}$ at the late stage of a NDW, the mass of product and nucleosynthesis are changed significantly in the strong MFs, they are less important than those in the early stage when the anti-neutrino luminosity is high. Therefore for the most models considered for the NDWs from PNSs, based on our calculations the influences of MFs and the net weak interactions on the nucleosynthesis is not significant.

astro-ph.HE↗
arXiv2010

Steady State Equilibrium Condition of $npe^{\pm}$ Gas and Its Application to Astrophysics

The steady equilibrium conditions for a mixed gas of neutrons, protons, electrons, positrons and radiation field (abbreviated as $npe^{\pm}$ gas) with/without external neutrino flux are investigated, and a general chemical potential equilibrium equation $μ_n=μ_p+Cμ_e$ is obtained to describe the steady equilibrium at high temperatures ($T>10^9$K). An analytic fitting formula of coefficient $C$ is presented for the sake of simplicity as the neutrino and antineutrino are transparent. It is a simple method to estimate the electron fraction for the steady equilibrium $npe^{\pm}$ gas that using the corresponding equilibrium condition. As an example, we apply this method to the GRB accretion disk and approve the composition in the inner region is approximate equilibrium as the accretion rate is low. For the case with external neutrino flux, we calculate the initial electron fraction of neutrino-driven wind from proto-neutron star model M15-l1-r1. The results show that the improved equilibrium condition makes the electron fraction decrease significantly than the case $μ_n=μ_p+μ_e$ when the time is less than 5 seconds post bounce, which may be useful for the r-process nucleosynthesis

astro-ph.HE↗
arXiv2009

Effect of Electron Screening on the Collapsing Process of Core-Collapse Supernovae

By using an average heavy nuclei model, the effects of the electron screening on electron capture (EC) in core-collapse supernovae are investigated. A one-dimension code based on the Ws15$M_{\sun}$ progenitor model is utilized to test the effects of electron screening during the collapsing process. The results show that, at high densities, the effects of EC on electron capture becomes significant. During the collapsing stage, the EC rate is decreased, the collapse timescale is prolonged and the leakage of the neutrino energy is increased. These effects lead to an appreciable decrease in the initial energy of the bounce shock wave. The effects of electron screeening in the other progenitor models are also discussed.

astro-ph.HE↗