Title: 2D chemical evolution model: the impact of galactic disc asymmetries on azimuthal chemical abundance variations Show Chinese title

Title: 二维化学演化模型：星系盘不对称性对方位化学丰度变化的影响

Abstract: Galactic disc chemical evolution models generally ignore azimuthal surface density variation that can introduce chemical abundance azimuthal gradients. Recent observations, however, have revealed chemical abundance changes with azimuth in the gas and stellar components of both the Milky Way and external galaxies.To quantify the effects of spiral arm density fluctuations on the azimuthal variations of the oxygen and iron abundances in disc galaxies. We develop a new 2D galactic disc chemical evolution model, capable of following not just radial but also azimuthal inhomogeneities. The density fluctuations resulting from a Milky Way-like N-body disc formation simulation produce azimuthal variations in the oxygen abundance gradients of the order of 0.1 dex. Moreover, in agreement with the most recent observations in external galaxies, the azimuthal variations are more evident in the outer galactic regions. The effect of an analytical spiral structure depends on the pattern speed and the number of spiral arms: larger azimuthal inhomogeneities are found when we consider a slower spiral structure and a single spiral arm. In conclusion we provided a new 2D chemical evolution model capable of following azimuthal density variations. Density fluctuations extracted from a Milky Way-like dynamical model lead to a scatter in the azimuthal variations of the oxygen abundance gradient in agreement with observations in external galaxies. Show Chinese abstract

Abstract: 星系盘的化学演化模型通常忽略可能引入化学丰度方位梯度的方位表面密度变化。然而，最近的观测结果揭示了银河系和外部星系中气体和恒星组分的化学丰度随方位的变化。为了量化螺旋臂密度波动对盘星系中氧和铁丰度方位变化的影响。我们开发了一个新的二维星系盘化学演化模型，能够不仅跟踪径向而且跟踪方位不均匀性。来自类似银河系的N体盘形成模拟的密度波动在氧丰度梯度中产生约0.1 dex的方位变化。此外，与外部星系的最新观测结果一致，方位变化在外部星系区域更为明显。分析螺旋结构的影响取决于图案速度和螺旋臂的数量：当我们考虑较慢的螺旋结构和单个螺旋臂时，发现更大的方位不均匀性。总之，我们提供了一个能够跟踪方位密度变化的新二维化学演化模型。从类似银河系的动力学模型中提取的密度波动导致氧丰度梯度的方位变化散射，与外部星系的观测结果一致。