Models of poststarburst (or "K+A") galaxies are constructed by combining fully three-dimensional hydrodynamic simulations of galaxy mergers with radiative transfer calculations of dust attenuation. Spectral line catalogs are generated automatically from moderate-resolution optical spectra calculated as a function of merger progress in each of a large suite of simulations. The mass, gas fraction, orbital parameters, and mass ratio of the merging galaxies are varied systematically, showing that the lifetime and properties of the K+A phase are strong functions of merger scenario. K+A durations are generally less than ~0.1-0.3 Gyr, significantly shorter than the commonly assumed 1 Gyr, which is obtained only in rare cases, owing to a wide variation in star formation histories resulting from different orbital and progenitor configurations. Combined with empirical merger rates, the model lifetimes predict rapidly-rising K+A fractions as a function of redshift that are consistent with results of large spectroscopic surveys, resolving tension between the observed K+A abundance and that predicted when one assumes the K+A duration is the lifetime of A stars (~1 Gyr). The effects of dust attenuation, viewing angle, and aperture bias on our models are analyzed. In some cases, the K+A features are longer-lived and more pronounced when AGN feedback removes dust from the center, uncovering the young stars formed during the burst. In this picture, the K+A phase begins during or shortly after the bright starburst/AGN phase in violent mergers, and thus offers a unique opportunity to study the effects of quasar and star formation feedback on the gas reservoir and evolution of the remnant. Analytic fitting formulae are provided for the estimates of K+A incidence as a function of merger scenario.
Multi-messenger constraints on the Hubble constant through combination of gravitational waves, gamma-ray bursts and kilonovae from neutron star mergers
Simulating the LOcal Web (SLOW) V. Thermodynamic Properties and Evolution of Local Galaxy Clusters
Ludwig-Maximilians-Universität München（慕尼黑大学）；Max Planck Institute for Astrophysics（马克斯·普朗克天体物理学研究所）；Univ. Lille, CNRS, Centrale Lille, UMR 9189 CRIStAL（里尔大学）；Université Paris-Saclay（巴黎萨克雷大学）
Simulating the impact of dust cooling on the statistical properties of the intracluster medium
从恒星和星系形成的第一阶段开始，非引力过程，如冲压压力剥离、超新星、星系风、活动星系核、星系-星系合并等。导致IGM中的恒星，金属以及尘埃的富集，通过星系物质喷射到IGM中。我们现在知道，这些过程与引力一起形成了结构的形成和演化。我们在这里提出的结构形成的流体动力学模拟实施的效果，由尘埃冷却大尺度结构的形成。我们关注星系团的尺度，研究星系团的统计性质。在这里，我们提出了我们的结果上的$T_X-M$和$L_X-M$标度关系，表现出的斜率和归一化的变化时，由尘埃冷却的标准辐射冷却模型。例如，对于包括尘埃冷却的模型，在$M=10^{14}$ M $_\odot$处，$T_X-M$关系的归一化仅改变最大2%，而在$T_X=1$ keV处，$L_X-T_X$的归一化改变多达10%。我们的研究表明，尘埃是一个额外的非引力过程，有助于塑造热ICM气体的物理状态。
