不同程式與條件下的超新星反饋之比較

Abstract

超新星(supernova)的存在對於星系的演化扮演重要的角色，星 系中的氣體形成恆星，恆星死亡後會形成超新星，在爆炸的過程中 將能量與氣體質量注入到周遭的星際物質中，對星際物質轉換成新 恆星的過程產生回饋(stellar feedback)。在模擬實驗中，回饋 的計算方式根據回饋影響範圍的不同，又可分為影響集中在超新星 所屬的最小空間單位的「局部回饋」(local feedback)以及影響 力擴張到臨近空間的「非局部回饋」(non-local feedback)，其 中局部回饋在模擬時的優勢是計算上比較單純，但是非局部回饋更 能忠實地反映出超新星爆炸產生的效應，而不容易讓超新星產生的 熱能與動能變化被背景氣體所掩蓋。並且現在對於矮星系、甚至星 系的模擬已經可以對星系中個別的超新星進行計算，但是高解析度 的模擬會需要耗費大量的資源。在本研究中我們使用兩種不同的模 擬程式來比較兩種不同的回饋模擬方式，並測試如何調整模擬回饋 時的計算方式，使其在低解析度的條件下也能重現原本只能在高解 析度模擬中看到的現象，而不改動算式根本的物理法則，為之後的 模擬提供加高解析度以外的替代方案。

Supernovae (SN) play a crucial role in galaxy evolution. As stars form from the interstellar medium (ISM) and eventually explode as supernovae, they release energy and gas back into the ISM, contribut- ing to the formation of new stars. However, the energy injected by supernovae slows this process because the heated gas is less likely to condense into stars. This phenomenon is known as stellar feedback. In computer simulations, stellar feedback is modeled using different methods based on how the feedback energy is distributed. When feed- back is applied to the smallest spatial unit (referred to as a “cell”), where the SN occurs, it is termed “local feedback.” This approach is simpler but less accurate. In contrast, “non-local feedback” spreads the SN energy to surrounding cells, ensure the formation of shock wave before the energy radiate away. While modern simulations can individually model supernovae, these high-resolution simulations are computationally expensive. In this study, we use three-dimensional isolated galaxy simulations with adaptive mesh refinement (AMR) to compare different stellar feedback methods. Additionally, we explore modifications to feedback calculations that can replicate phenomena typically only observed in high-resolution simulations in lower-resolution simulations. These modifications may provide an alternative to increasing resolution in future simulations.