The SAMI Galaxy Survey: Physical drivers of stellar-gas kinematic misalignments in the nearby Universe
A. Ristea, L. Cortese, A. Fraser-McKelvie, S. Brough, J. J. Bryant, B. Catinella, S. M. Croom, B. Groves, S. N. Richards, J. van de Sande, J. Bland-Hawthorn, M.… 展开作者
A. Ristea, L. Cortese, A. Fraser-McKelvie, S. Brough, J. J. Bryant, B. Catinella, S. M. Croom, B. Groves, S. N. Richards, J. van de Sande, J. Bland-Hawthorn, M. S. Owers, J. S. Lawrence
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25 pages (5 in appendices); 11 figures (2 in appendices); accepted for publication in MNRAS
Misalignments between the rotation axis of stars and gas are an indication of external processes shaping galaxies throughout their evolution. Using observations of 3068 galaxies from the SAMI Galaxy Survey, we compute global kinematic position angles for 1445 objects with reliable kinematics and identify 169 (12%) galaxies which show stellar-gas misalignments. Kinematically decoupled features are more prevalent in early-type/passive galaxies compared to late-type/star-forming systems. Star formation is the main source of gas ionisation in only 22% of misaligned galaxies; 17% are Seyfert objects, while 61% show Low-Ionisation Nuclear Emission-line Region features. We identify the most probable physical cause of the kinematic decoupling and find that, while accretion-driven cases are dominant, for up to 8% of our sample, the misalignment may be tracing outflowing gas. When considering only misalignments driven by accretion, the acquired gas is feeding active star formation in only $\sim$1/4 of cases. As a population, misaligned galaxies have higher Sérsic indices and lower stellar spin & specific star formation rates than appropriately matched samples of aligned systems. These results suggest that both morphology and star formation/gas content are significantly correlated with the prevalence and timescales of misalignments. Specifically, torques on misaligned gas discs are smaller for more centrally concentrated galaxies, while the newly accreted gas feels lower viscous drag forces in more gas-poor objects. Marginal evidence of star formation not being correlated with misalignment likelihood for late-type galaxies suggests that such morphologies in the nearby Universe might be the result of preferentially aligned accretion at higher redshifts.
The SAMI Galaxy Survey: Gas velocity dispersions in low-$z$ star-forming galaxies and the drivers of turbulence
我们推断的内在电离气体运动学的383恒星形成星系在一个范围内的综合恒星形成率（SFR $\in [10^{-3}, 10^2]$ M $_\odot$年$^{-1}$）在$z \lesssim 0.1$使用一致的三维正演模拟技术。总样本是SAMI星系巡天和SAMO巡天的星系组合。对于典型的低$z$星系从SAMI星系巡天，我们发现的垂直速度色散（$σ_{v, z}$）是正相关的恒星形成率，恒星质量，HI气体质量和旋转速度的措施。最大的相关性是与恒星形成率表面密度（$Σ_\text{SFR}$）。使用总样本，我们发现$σ_{v, z}$在范围SFR $\in$ [ $10^{-3}$，1] M $_\odot$ yr $^{-1}$从$17\pm3$ km s $^{-1}$到$24\pm5$ km s $^{-1}$内缓慢增加，然后急剧增加到$σ_{v, z}$ $\sim 80$ km s $^{-1}$，对于SFR $\gtrsim 1$ M $_\odot$ yr $^{-1}$。这与最近的理论模型是一致的，该模型提出了由恒星形成反馈过程驱动的$σ_{v, z}$地板，在较高的SFR下，由气体通过圆盘的引力传输驱动的$σ_{v, z}$向上翻转。
Large-scale and local environmental drivers of quenching: tracing H$α$ concentration in X-ray and optical galaxy groups
The University of Sydney（悉尼大学）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（三维全天空天体物理学卓越研究中心）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Beijing Normal University（北京师范大学）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）
