论文标题
强大的HI运动学大型超湿星系：弱反馈形成场景的提示
Robust HI kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario
论文作者
论文摘要
我们研究了六个孤立气体富含气体表面亮度星系的样品的气体运动学，该类别称为Ultra-diffuse星系（UDGS）。最近，这些星系被证明是来自Baryonic Tully-Fisher关系（BTFR）的离群值，因为它们的旋转速度比其重骨质量慢得多，并且具有与宇宙学平均值相似的Baryon馏分。通过3D运动学建模拟合技术，我们表明我们的UDG中的HI分布在“薄”定期旋转盘中，并确定它们的旋转速度和气体速度分散。我们重新访问BTFR，从其他研究中添加了星系。我们发现从BTFR的偏差与圆盘尺度长度之间的趋势在圆形速度<45 km/s之间有效，而我们的UDG处于极端。根据我们的发现，我们建议我们的UDG的较高的重子部分可能起源，因为它们的恒星形成速率表面密度较低，因此它们的恒星形成速率低，因此它们没有从光盘中排出大量的气体。同时，我们发现我们的UDG可能具有高于平均水平的特定角度动量，这可以解释其较大的光学尺度长度。
We study the gas kinematics of a sample of six isolated gas-rich low surface brightness galaxies, of the class called ultra-diffuse galaxies (UDGs). These galaxies have recently been shown to be outliers from the baryonic Tully-Fisher relation (BTFR), as they rotate much slower than expected given their baryonic mass, and to have baryon fractions similar to the cosmological mean. By means of a 3D kinematic modelling fitting technique, we show that the HI in our UDGs is distributed in "thin" regularly rotating discs and we determine their rotation velocity and gas velocity dispersion. We revisit the BTFR adding galaxies from other studies. We find a previously unknown trend between the deviation from the BTFR and the disc scale length valid for dwarf galaxies with circular speeds < 45 km/s, with our UDGs being at the extreme end. Based on our findings, we suggest that the high baryon fractions of our UDGs may originate due to the fact that they have experienced weak stellar feedback, likely due to their low star formation rate surface densities, and as a result they did not eject significant amounts of gas out of their discs. At the same time, we find indications that our UDGs may have higher-than-average stellar specific angular momentum, which can explain their large optical scale lengths.
