Data from: Global H I asymmetries in IllustrisTNG: a diversity of physical processes disturb the cold gas in galaxies

Observations of the cold neutral atomic hydrogen (H i) in and around disc galaxies have revealed that spatial and kinematic asymmetries are common place, and are reflected in the global H i spectra. We use the TNG100 box from the IllustrisTNG suite of cosmological simulations to study the conditions under which these asymmetries may arise in current theoretical galaxy formation models. We find that more than 50 per cent of the sample has at least a 10 per cent difference in integrated flux between the high- and low-velocity half of the spectrum, thus the typical TNG100 galaxy has an H i profile that is not fully symmetric. We find that satellite galaxies are a more asymmetric population than centrals, consistent with observational results. Using halo mass as a proxy for environment, this trend appears to be driven by the satellite population within the virial radius of haloes more massive than 1013 M·, typical of medium/large groups. We show that, while the excess of H i asymmetry in group satellites is likely driven by ram pressure, the bulk of the asymmetric H i profiles observed in TNG100 are driven by physical processes able to affect both the central and satellite populations. Our results highlight how asymmetries are not driven solely by environment, and multiple physical processes can produce the same asymmetric shape in global H i spectra.

对盘星系及其周围的冷中性原子氢（H i）的观测表明，空间与运动学不对称现象普遍存在，并在整体H i谱中有所体现。我们采用IllustrisTNG宇宙学模拟套件的TNG100模拟箱，探究当前星系形成理论模型中这类不对称现象的产生条件。我们发现，超过50%的样本在谱线高速与低速半区的积分通量差异至少达到10%，因此典型的TNG100星系的H i轮廓并非完全对称。我们发现，卫星星系的不对称性水平高于中心星系，这与观测结果一致。以晕质量作为环境的代理变量，该趋势似乎由质量大于10^13 M⊙的晕（典型的中等/大质量星系群）维里半径内的卫星星系群体主导。我们的研究表明，尽管星系群卫星星系的H i不对称性过剩可能由冲压压力驱动，但TNG100中观测到的绝大多数不对称H i轮廓，是由能够同时影响中心星系与卫星星系的物理过程产生的。我们的结果凸显出，不对称性并非仅由环境因素主导，多种物理过程均可在整体H i谱中产生相同的不对称轮廓。