Gas kinematics, morphology and angular momentum in the FIRE simulations
Gas kinematics, morphology and angular momentum in the FIRE simulations
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DOI：
10.1093/mnras/stx2482
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发表时间：
2017-05
影响因子：
4.8
通讯作者：
K. El-Badry;E. Quataert;A. Wetzel;P. Hopkins;D. Weisz;T. K. Chan;Alex Fitts;M. Boylan-Kolchin;D. Kerevs;C. Faucher-Giguère;S. Garrison-Kimmel
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作者：
K. El-Badry;E. Quataert;A. Wetzel;P. Hopkins;D. Weisz;T. K. Chan;Alex Fitts;M. Boylan-Kolchin;D. Kerevs;C. Faucher-Giguère;S. Garrison-Kimmel
作者：El-Badry， K；Quataert E;吉姆,一个;霍普金斯,PF;薇,博士;陈,TK;费茨,;Boylan-Kolchin, M;凯瑞斯语,D;faucher - giguere CA;摘要：©2017 The Author(S)。我们研究了z = 0气体运动学，形态学和角动量含量在一套宇宙学变焦模拟从FIRE项目跨越Mstar = 106-11M⊙。随着星系质量的增加，气体的旋转支持也越来越大。在质量最低的星系（Mstar l 108M⊙）中，气体不能形成形态盘，主要是弥散和压力支持。在中等质量（Mstar = 108-10M⊙）的星系中，气体的运动学和形态范围很广，从薄的旋转圆盘到不规则的球体，净旋转可以忽略不计。所有的大质量星系（Mstar = 1010-11M⊙）都形成旋转支撑的气体盘。许多星系未能形成盘状的晕在其环星系介质中含有高角动量气体。中央星系气体的比角动量与暗物质晕的比角动量随星系质量的增加而显著增加，从Mstar = 106-7M⊙处的< jgas > / < jDM > ~ 0.1到Mstar = 1010-11M⊙处的< jgas > / < jDM > ~ 2。在质量最低的星系中，旋转支撑的减少是由于(a)恒星反馈和紫外线背景在后期抑制了高角动量气体的吸积，以及(b)恒星反馈驱动了大的非圆形气体运动。我们大致再现了观测到的星系质量、气体旋转速度、大小和角动量之间的比例关系，但可能在某种程度上低估了在观测到的最低质量（Mstar = (106- 2 × 107) M⊙）处的盘状、高角动量星系的发生率。恒星优先从星系中心附近的低角动量气体中形成，它们的旋转支持比气体少。通常的假设是恒星遵循与气体相同的旋转曲线，因此大大高估了模拟星系的恒星角动量，特别是在低质量时。
Author(s): El-Badry, K; Quataert, E; Wetzel, A; Hopkins, PF; Weisz, DR; Chan, TK; Fitts, A; Boylan-Kolchin, M; Keres, D; Faucher-Giguere, CA; Garrison-Kimmel, S | Abstract: © 2017 The Author(s). We study the z = 0 gas kinematics, morphology and angular momentum content of isolated galaxies in a suite of cosmological zoom-in simulations from the FIRE project spanning Mstar = 106-11M⊙. Gas becomes increasingly rotationally supported with increasing galaxy mass. In the lowest mass galaxies (Mstar l 108M⊙), gas fails to form a morphological disc and is primarily dispersion and pressure supported. At intermediate masses (Mstar = 108-10M⊙), galaxies display a wide range of gas kinematics and morphologies, from thin, rotating discs to irregular spheroids with negligible net rotation. All the high-mass (Mstar = 1010-11M⊙) galaxies form rotationally supported gas discs. Many of the haloes whose galaxies fail to form discs harbour high angular momentum gas in their circumgalactic medium. The ratio of the specific angular momentum of gas in the central galaxy to that of the dark matter halo increases significantly with galaxy mass, from 〈jgas〉/〈jDM〉 ~ 0.1 at Mstar = 106-7M⊙ to 〈jgas〉/〈jDM〉 ~ 2 at Mstar = 1010-11M⊙. The reduced rotational support in the lowest mass galaxies owes to (a) stellar feedback and the UV background suppressing the accretion of high angular momentum gas at late times, and (b) stellar feedback driving large non-circular gas motions. We broadly reproduce the observed scaling relations between galaxy mass, gas rotation velocity, size and angular momentum, but may somewhat underpredict the incidence of disky, high angular momentum galaxies at the lowest observed masses (Mstar = (106- 2 × 107) M⊙). Stars form preferentially from low angular momentum gas near the galactic centre and are less rotationally supported than gas. The common assumption that stars follow the same rotation curve as gas thus substantially overestimates the simulated galaxies' stellar angular momentum, particularly at low masses.