论文标题
以这种方式出生：薄盘，厚度圆盘和各向同性球体形成2乳白色 - 道路银河系模拟
Born this way: thin disc, thick disc, and isotropic spheroid formation in FIRE-2 Milky-Way-mass galaxy simulations
论文作者
论文摘要
我们通过研究从出生到今天，使用Fire-2 LCDM宇宙学缩放模拟模拟的FIRE-2 LCDM宇宙缩放模拟的轨道演化，研究了乳白色质量星系的形成。我们根据它们的轨道圆形将原位恒星分为各向同性球体，厚盘和薄盘，并表明这些成分分别以时间顺序的序列组装，分别从早期到晚期组装。所有模拟星系都经历了爆发星形形成的早期阶段，该阶段将过渡到后期稳定阶段。这种过渡与内部CGM病毒恢复的时间一致。在爆发阶段的早期，星系具有不规则的形态，新恒星出生在径向轨道上。这些恒星今天发展成为各向同性球体。大部分厚碟恒星在中间时间形成，在块状disc``旋转''阶段，比球形形成的峰稍晚。 At late times, once the CGM virializes and star formation ``cools down," stars are born on circular orbits within a narrow plane. Those stars mostly inhabit thin discs today. Broadly speaking, stars with disc-like or spheroid-like orbits today were born that way. Mergers onto discs and secular processes do affect kinematics in our simulations, but play only secondary roles in populating thick-disc and in situ z = 0的球体种群与稳态过渡时间的相似性尺度相似，这表明形态年龄的年龄可以与星系中的CGM病毒时间联系起来。
We investigate the formation of Milky-Way-mass galaxies using FIRE-2 LCDM cosmological zoom-in simulations by studying the orbital evolution of stars formed in the main progenitor of the galaxy, from birth to the present day. We classify in situ stars as isotropic spheroid, thick-disc, and thin-disc according to their orbital circularities and show that these components are assembled in a time-ordered sequence from early to late times, respectively. All simulated galaxies experience an early phase of bursty star formation that transitions to a late-time steady phase. This transition coincides with the time that the inner CGM virializes. During the early bursty phase, galaxies have irregular morphologies and new stars are born on radial orbits; these stars evolve into an isotropic spheroidal population today. The bulk of thick-disc stars form at intermediate times, during a clumpy-disc ``spin-up'' phase, slightly later than the peak of spheroid formation. At late times, once the CGM virializes and star formation ``cools down," stars are born on circular orbits within a narrow plane. Those stars mostly inhabit thin discs today. Broadly speaking, stars with disc-like or spheroid-like orbits today were born that way. Mergers onto discs and secular processes do affect kinematics in our simulations, but play only secondary roles in populating thick-disc and in situ spheroid populations at z=0. The age distributions of spheroid, thick disc, and thin disc populations scale self-similarly with the steady-phase transition time, which suggests that morphological age dating can be linked to the CGM virialization time in galaxies.
