We extend a chemical evolution model relating galaxy stellar mass and gas-phase oxygen abundance (the mass-metallicity relation) to explicitly consider the mass-dependence of galaxy gas fractions and outflows. Using empirically derived scalings of galaxy mass with halo virial velocity in conjunction with the most recent observations of z~0 total galaxy cold gas fractions and the mass-metallicity relation, we place stringent global constraints on the magnitude and scaling of the efficiency with which star forming galaxies expel metals. We demonstrate that under the assumptions that metal accretion is negligible and the stellar initial mass function does not vary, efficient outflows are required to reproduce the mass-metallicity relation; without winds, gas-to-stellar mass ratios >~ 0.3 dex higher than observed are needed. Moreover, z=0 gas fractions are low enough that while they have some effect on the magnitude of outflows required, the slope of the gas fraction--stellar mass relation does not strongly affect our conclusions on how the wind efficiencies must scale with galaxy mass. Despite systematic uncertainties in the normalization and slope of the mass-metallicity relation, we show that the metal expulsion efficiency zetaw=(Zw/Zg)etaw (where Zw is the wind metallicitiy and Zg is the interstellar medium metallicity) must be both high and scale steeply with mass. Specifically, we show that zetaw >> 1 and zetaw proportional to vvir^-3 or steeper. In contrast, momentum- or energy-driven outflow models suggest that etaw should scale as vvir^-1 or vvir^-2, respectively, implying that the Zw-Mstar relation should be shallower than the Zg-Mstar relation. [abridged]
The effect of progenitor metallicity on Type Ia Supernovae (SNe Ia) has important cosmological implications due to the need for these standardizable candles to be compared across large spans of cosmic time in which the progenitor stars might have different properties. Theoretical models have come to different conclusions as to the wavelength range impacted by metallicity differences, leading to differing interpretations of the growing sample of UV observations. Recent work has claimed a correlation between the mid-UV flux of SNe Ia measured from Swift grism spectra and the gas-phase metallicit…
Understanding the relationship between the cosmic web and the gas content of galaxies is a key step towards understanding galaxy evolution. However, the impact of the cosmic web on the growth of galaxies and dark matter halos is not yet properly understood. We report a detection of the effect of the cosmic web on the galaxy stellar mass - gas phase metallicity relation of low redshift star-forming galaxies, using SDSS data. The proximity of a galaxy to a node, independently of stellar mass and overdensity, influences its gas-phase metallicity, with galaxies closer to nodes displaying higher ch…
We study the impact of different galaxy statistics and empirical metallicity scaling relations on the merging rates and on the properties of compact objects binaries. First, we analyze the similarities and differences of using the star formation rate functions or the stellar mass functions as galaxy statistics for the computation of the cosmic star formation rate density. Then we investigate the effects of adopting the Fundamental Metallicity Relation or a classic Mass Metallicity Relation to assign metallicity to galaxies with given properties. We find that when the Fundamental Metallicity Re…
Massive early-type galaxies typically have two subpopulations of globular clusters (GCs) which often reveal radial colour (metallicity) gradients. Collating gradients from the literature, we show that the gradients in the metal-rich and metal-poor GC subpopulations are the same, within measurement uncertainties, in a given galaxy. Furthermore, these GC gradients are similar in strength to the {\it stellar} metallicity gradient of the host galaxy. At the very largest radii (e.g. greater than 8 galaxy effective radii) there is some evidence that the GC gradients become flat with near constant me…
Revisiting the fundamental metallicity relation with observation and simulation
University of Science and Technology of China（中国科学技术大学）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Durham University（杜伦大学）
The stellar metallicity gradients in galaxy discs in a cosmological scenario
盘状星系的恒星金属丰度梯度提供了有关盘状星系组装、恒星形成过程和化学演化的信息。它们还可能存储有关动力学过程的信息，这些过程可能影响气相和恒星成分中化学元素的分布。我们在宇宙学模拟中研究了恒星盘的恒星金属丰度梯度。我们探讨了恒星金属丰度梯度对恒星年龄和恒星盘的大小和质量的依赖性。我们使用的星系从宇宙学流体动力学模拟包括物理动机的超新星反馈和化学演化。估算了不同年龄恒星的金属丰度分布。我们面对我们的数字调查结果从加州调查。模拟的恒星盘被发现有金属丰度剖面的斜率在全球协议与观测。低恒星质量星系的金属丰度斜率变化更大。当标准化的半质量半径，恒星的金属丰度梯度没有表现出任何依赖性和色散显着增加，无论星系质量。在$10^{10}$ M $_{\odot}$周围具有恒星质量的镓，其金属丰度负梯度较陡。恒星金属丰度梯度与半质量半径相关。然而，当它们被半质量半径归一化时，相关信号不存在。正年龄梯度的星盘被检测到有负和正的金属丰度梯度，这取决于最近的恒星形成活动在中心地区的相对重要性。作为恒星质量函数的金属丰度梯度的大分散可以归因于动力学过程的影响，例如合并/相互作用和/或迁移，以及那些调节气体转化为恒星的过程。[删节]
Recent X-ray observations of galaxy clusters show that the distribution of intra-cluster medium (ICM) metallicity is remarkably uniform in space and time. In this paper, we analyse a large sample of simulated objects, from poor groups to rich clusters, to study the dependence of the metallicity and related quantities on the mass of the systems. The simulations are performed with an improved version of the Smoothed-Particle-Hydrodynamics \texttt{GADGET-3} code and consider various astrophysical processes including radiative cooling, metal enrichment and feedback from stars and active galactic n…
