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arXiv 1901.02886astro-ph.GAastro-ph.CO
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宇宙学模拟中的尘埃标度关系

Dust scaling relations in a cosmological simulation

Kuan-Chou Hou, Shohei Aoyama, Hiroyuki Hirashita, Kentaro Nagamine, Ikkoh Shimizu

摘要:

为了研究尘埃在宇宙结构形成过程中的演化,我们采用尘埃富集模型,在宇宙体积中进行了光滑粒子流体动力学模拟。我们采用的尘埃演化模型,代表两个尺寸的粒度分布,并考虑到恒星尘埃的生产和星际尘埃处理。我们研究了尘埃质量函数和尘埃的标度性质的星系的特性。模拟广泛地再现了观测到的尘埃质量函数在红移$z = 0$,除了它过度产生的尘埃质量$M_\mathrm{d} \gtrsim 10^{8}$ ${\rm M}_\odot$的质量端。这种过剩是由于大量的气体/金属丰富的系统过度生产,但我们也注意到,恒星质量和气相金属丰度之间的关系是由我们的配方相当好地再现。尘埃-气体比与金属丰度的关系与$z=0$观测结果吻合较好,表明尘埃演化在我们的宇宙学模拟中得到了成功的实现。恒星的形成不仅消耗气体,也消耗尘埃,导致星系高质量端的尘埃-恒星质量比呈下降趋势。我们还研究了红移演化到$z \sim~ 5$,并发现星系的平均最高尘埃质量在$z = 1-2$。对于粒度分布,我们发现,星系的金属丰度$\sim 0.3~ Z_\odot$往往有最高的小到大的颗粒丰度比,因此,在这些星系的消光曲线具有最陡峭的紫外线斜率。

英文摘要:

To study the dust evolution in the cosmological structure formation history, we perform a smoothed particle hydrodynamic simulation with a dust enrichment model in a cosmological volume. We adopt the dust evolution model that represents the grain size distribution by two sizes and takes into account stellar dust production and interstellar dust processing. We examine the dust mass function and the scaling properties of dust in terms of the characteristics of galaxies. The simulation broadly reproduces the observed dust mass functions at redshift $z = 0$, except that it overproduces the massive end at dust mass $M_\mathrm{d} \gtrsim 10^{8}$ ${\rm M}_\odot$. This overabundance is due to overproducing massive gas/metal-rich systems, but we also note that the relation between stellar mass and gas-phase metallicity is reproduced fairly well by our recipe. The relation between dust-to-gas ratio and metallicity shows a good agreement with the observed one at $z=0$, which indicates successful implementation of dust evolution in our cosmological simulation. Star formation consumes not only gas but also dust, causing a decreasing trend of the dust-to-stellar mass ratio at the high-mass end of galaxies. We also examine the redshift evolution up to $z \sim~ 5$, and find that the galaxies have on average the highest dust mass at $z = 1-2$. For the grain size distribution, we find that galaxies with metallicity $\sim 0.3~ Z_\odot$ tend to have the highest small-to-large grain abundance ratio; consequently, the extinction curves in those galaxies have the steepest ultraviolet slopes.

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