标题： 自洽棒和潮汐棒的起源和寿命在模拟盘星系中 显示英文标题

标题： Origins and lifetimes of secular and tidal bars in simulated disc galaxies

摘要： 我们研究了TNG50宇宙学模拟中307个银河系质量盘状星系中恒星棒的形成。 大多数棒在动态冷盘中迅速形成，这发生在中心恒星质量超过暗物质质量之后。 在这种情况下，棒的形成与由盘自引力驱动的长期不稳定性一致，这种不稳定性将恒星轨道组织成一个连贯的棒结构。 然而，大约25%的棒星系在棒形成时是暗物质主导的，$t_{bar}$，并且此后一直如此。 我们使用一个新的指标，$S_{bar}$，量化作用在星系上的潮汐场，来追溯这些棒的起源，这些棒是由经过的卫星或合并引起的潮汐扰动。 在棒形成时，我们发现$S_{bar}$与中心恒星与暗物质质量比之间存在负相关，表明暗物质主导的盘需要更强的潮汐力才能触发棒的形成。 这些由潮汐引起的棒比那些长期形成的棒更可能短暂，尽管棒的性质 otherwise 相似。 然而，宿主星系有所不同：长期棒出现在相对紧凑的盘中，而潮汐棒出现在扩展的盘中，其特性类似于无棒星系。 因此，潮汐扰动可以在 otherwise 稳定于长期形成的星系中诱导棒，突显了内部星系结构和外部环境在棒形成中的双重作用。 显示英文摘要

摘要： We investigate the formation of stellar bars in 307 Milky Way-mass disc galaxies in the TNG50 cosmological simulation. Most bars form rapidly in dynamically cold discs shortly after the central stellar mass exceeds that of dark matter. In these cases, bar formation is consistent with secular instabilities driven by the disc's self-gravity, which organises stellar orbits into a coherent bar structure. However, around 25 per cent of barred galaxies are dark matter dominated at the time of bar formation, $t_{bar}$, and remain so thereafter. We trace the origin of these bars to tidal perturbations induced by passing satellites or mergers using a new metric, $S_{bar}$, quantifying the tidal field acting on the galaxy. At the time of bar formation, we find a negative correlation between $S_{bar}$ and the central stellar-to-dark matter mass fraction, indicating that more dark matter-dominated discs require stronger tides to trigger bar formation. These tidally induced bars are more likely to be transient than those that form secularly, although bar properties are otherwise similar. However, the host galaxies differ: secular bars arise in relatively compact discs, while tidal bars appear in extended discs whose properties resemble those of unbarred galaxies. Tidal perturbations can therefore induce bars in galaxies otherwise stable to secular formation, highlighting the dual role of the internal galactic structure and the external environment in bar formation.