arXiv subjects

Wun-Yi Chen

Publications and source records attributed to Wun-Yi Chen.

3 recordsLinked to original sources

arXiv2026

Observable Signatures of Supernova Shock Breakout in Confined Circumstellar Medium

Supernova shock breakout encodes rich information about stellar explosions, including the properties of the progenitor, the explosion mechanism, and the circumstellar environment. We present the first two-dimensional multigroup radiation-hydrodynamic simulations of shock breakout from Red Supergiant (RSG) progenitor stars embedded in confined circumstellar medium (CSM) produced shortly before core collapse. Our simulations reveal that radiation escaping ahead of the shock forms a radiative precursor that pre-accelerates the CSM and induces strong hydrodynamic mixing. This mixing substantially modifies the structure and evolution of the breakout photosphere and, consequently, the emergent radiation. The resulting bolometric light curves reach peak luminosities of $1.43$-$3.15 \times 10^{44}\ \mathrm{erg\ s^{-1}}$ with duration of $4.1\text{--}35.4$~hr, with these signatures controlled by the CSM mass and the confined radius. Our multiwavelength calculations further reveal a pronounced extreme-ultraviolet emission, where ionizing photons of energies ${\ge}54.4$~eV can sustain flash-ionized He-II and power strong emission from its recombination line of $λ4686$ angstrom. Furthermore, we identify diagnostic signatures of shock breakout with dense CSM and assess their detectability with Einstein Probe and ULTRASAT. Our models and predictions provide promising diagnostics of shock breakout in CSM that may be detectable by current and forthcoming high-cadence ultraviolet and X-ray space telescopes.

astro-ph.HE↗

arXiv2026

Multi-wavelength Signatures of Supernova Shock Breakout from Red Supergiants in Two Dimensions

We present new two-dimensional radiation hydrodynamic simulations of supernova shock breakout from red supergiants using the $\texttt{CASTRO}$ code. Our progenitors are 20 and 25 M$_{\odot}$ solar-metallicity stars evolved from the zero-age main sequence with $\texttt{MESA}$ and exploded in one dimension using $\texttt{FLASH}$. We consider a range of circumstellar media (CSM) produced by stellar winds to investigate how pre-explosion mass-loss affects shock breakout. The multigroup flux-limited diffusion scheme in $\texttt{CASTRO}$ captures the interaction between the explosion shock, its radiation precursor, and the surrounding CSM. We find that strong radiation precursors, generated by radiation leakage behind the shock, can drive fluid instabilities and move the effective photosphere outward before the shock reaches the stellar surface. The resulting breakout emissions reach peak luminosities of ${\sim}10^{44}$ erg s$^{-1}$ with full-width half-maximum durations of 1-3 hr, , fainter and longer than previous 1D models. The light-curve colors gradually evolve from blue to red after the peak. The 25 M$_{\odot}$ model with explosion energy $E \sim 1.69\times10^{51}$ erg produces ${\sim}$10-30\% higher maximum luminosity than the 20 M$_{\odot}$ model with $E \sim 1.09\times10^{51}$ erg. The dense CSM further extends the breakout rise time by increasing the photon diffusion. These results provide new constraints on red supergiant atmospheres and mass-loss histories prior to core collapse.

astro-ph.HE↗

arXiv2024

Multidimensional Radiation Hydrodynamics Simulations of Supernova 1987A Shock Breakout

Shock breakout is the first electromagnetic signal from supernovae (SNe), which contains important information on the explosion energy and the size and chemical composition of the progenitor star. This paper presents the first two-dimensional (2D) multi-wavelength radiation hydrodynamics simulations of SN 1987A shock breakout by using the $\texttt{CASTRO}$ code with the opacity table, $\texttt{OPAL}$, considering eight photon groups from infrared to X-ray. To investigate the impact of the pre-supernova environment of SN 1987A, we consider three possible circumstellar medium (CSM) environments: a steady wind, an eruptive mass loss, and the existence of a companion star. In sum, the resulting breakout light curve has an hour duration and its peak luminosity of $\sim 4\times 10^{46}\,\rm{erg\,s^{-1}}$ then following a decay rate of $\sim 3.5\,\rm{mag\,hour^{-1}}$ in X-ray. The dominant band transits to UV around 3 hours after the initial breakout, and its luminosity has a decay rate of $\sim 1.5\,\rm{mag\,hour^{-1}}$ that agrees well with the observed shock breakout tail. The detailed features of breakout emission are sensitive to the pre-explosion environment. Furthermore, our 2D simulations demonstrate the importance of multidimensional mixing and its impacts on shock dynamics and radiation emission. The mixing emerging from the shock breakout may lead to a global asymmetry of SN ejecta and affect its later supernova remnant formation.

astro-ph.HE↗