矮星系及其環繞星系介質在宇宙時間下的共同演化

Abstract

根據現代宇宙學，宇宙從較小的結構逐漸形成較大的結構。因此，研究矮星系的演化對於理解像銀河系這樣更大質量星系的形成和演化至關重要。在星系的演化歷史中，星系與其周圍的星系周介質(CGM)和星系際介質(IGM)之間的相互作用起著重要作用。從CGM和IGM吸積的氣體冷卻並流入星系，促進恆星形成。與此同時，來自恆星和中心超大質量黑洞(SMBH)的回饋將能量和物質返回CGM和IGM，形成一個包含各種氣體相態的動態生態系統。 在本研究中，我們集中研究了在紅移(z)為0、1和2的星形成矮星系中從周圍環境吸積氣體。我們使用Gizmo程式中的無網格方法進行了包含多種物理的3D、N體和流體動力學模擬。為了現實地解決這個問題，我們採用了最新宇宙學模擬IllustrisTNG的結果作為我們模擬的初始條件。我們檢查了吸積CGM氣體的物理性質，並研究了它如何影響不同環境中的矮星系演化。 我們的結果顯示，來自CGM的氣體可以顯著影響星系的重子含量，有助於總質量和恆星形成的增長。同一紅移下，來自CGM的貢獻也顯示出一致性。然而，來自IGM的氣體吸積在z∼2時顯著。這種來自IGM的強吸積流也觸發了星系中心的強烈AGN活動和緻密恆星形成。

According to modern cosmology, the universe forms hierarchically from smaller structures to larger ones. Therefore, studying the evolution of dwarf galaxies is crucial for understanding the formation and evolution of more massive galaxies, such as the Milky Way. Throughout a galaxy’s evolutionary history, the interactions between the galaxy, its circumgalactic medium (CGM), and the intergalactic medium (IGM) play important roles. Gas accreted from the CGM and IGM cools and flows into a galaxy, fueling star forma- tion. Meanwhile, feedback from stars and the central supermassive black hole (SMBH) returns energy and matter to the CGM and IGM, resulting in a dynamic ecosystem with various gas phases. In this research, we focus on the accretion of gas from the surrounding environment to star-forming dwarf galaxies at redshifts (z) of 0, 1, and 2. We present 3D N-body and hydrodynamical simulations with multi-physics using the meshless method in the Gizmo code. To address the question realistically, we adopt the results from the state-of-the-art cosmology simulation, IllustrisTNG, as the initial conditions for our simulations. We have examined the physical properties of the accreting CGM gas and studied how it affects the evolution of dwarf galaxies in different environments. Our results demonstrate that gas from the CGM can significantly impact the galaxy’s baryon content, contributing to growth in total mass and star formation. The contribution from the CGM also shows consistency at the same redshift. However, gas accretion from the IGM is significant at z ∼ 2. This strong accretion flow from the IGM also triggers intense AGN activity and compact star formation at the galaxy’s center.