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arXiv 1807.07580astro-ph.GA
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哈勃前沿场中$z=6-9$星系恒星质量函数和UV光度函数的演化

Evolution of the galaxy stellar mass functions and UV luminosity functions at $z=6-9$ in the Hubble Frontier Fields

Rachana Bhatawdekar, Christopher J. Conselice, Berta Margalef-Bentabol, Kenneth Duncan

摘要:

本文对前线场星系团MACSJ0416.1-2403及其平行场中的$z=6-9$星系的恒星质量函数(GSMF)和紫外光度函数(UV LF)的演化进行了新的测量。为了获得这些结果,我们得到的恒星质量,我们的样本拟合合成恒星人口模型,以他们所观察到的光谱能量分布与列入星云发射线。这是迄今为止测量的距离质量函数中最深和最远的,并且探测到M $_{*} = 10^{6.8}M_{\odot}$的水平。本研究的主要结果是,我们的GSMF的低质量端达到这些极限,红移似乎从$z=6$的$-1.98_{-0.07}^{+0.07}$到$z=9$的$-2.38_{-0.88}^{+0.72}$变得更陡,比之前在稍低的红移下观察到的质量函数更陡,并且我们没有发现探测质量范围内发生转换的证据。我们进一步证明,这些系统的紫外LF似乎也显示出在最高的红移陡峭,没有任何证据的营业额的光度范围内探测。我们的$M_{\mathrm{UV}}-M_{*}$关系表现出较浅的斜率比以前观察到的,是根据一个恒定的质光比。积分我们的GSMF,我们发现恒星的质量密度从$z=9$到$z=6$增加了$\sim15_{-6}^{+21}$倍。我们估计了尘埃校正的恒星形成率(SFR),以计算我们样本的特定恒星形成率($\mathrm{sSFR}=\mathrm{SFR/M_{*}}$),并发现对于固定的恒星质量$5\times10^{9}M_{\odot}$,sSFR $\propto(1+z)^{2.01\pm0.16}$。最后,从我们的新的测量,我们估计的紫外光度密度($ρ_{\textrm{UV}}$),并发现我们的结果支持$ρ_{\textrm{UV}}$向高红移平稳下降。

英文摘要:

We present new measurements of the evolution of the galaxy stellar mass functions (GSMF) and UV luminosity functions (UV LF) for galaxies from $z=6-9$ within the Frontier Field cluster MACSJ0416.1-2403 and its parallel field. To obtain these results, we derive the stellar masses of our sample by fitting synthetic stellar population models to their observed spectral energy distribution with the inclusion of nebular emission lines. This is the deepest and farthest in distance mass function measured to date and probes down to a level of M$_{*} = 10^{6.8}M_{\odot}$. The main result of this study is that the low-mass end of our GSMF to these limits and redshifts appears to become steeper from $-1.98_{-0.07}^{+0.07}$ at $z=6$ to $-2.38_{-0.88}^{+0.72}$ at $z=9$, steeper than previously observed mass functions at slightly lower redshifts, and we find no evidence of turnover in the mass range probed. We furthermore demonstrate that the UV LF for these system also appears to show a steepening at the highest redshifts, without any evidence of turnover in the luminosity range probed. Our $M_{\mathrm{UV}}-M_{*}$ relation exhibit shallower slopes than previously observed and are in accordance with a constant mass-to-light ratio. Integrating our GSMF, we find that the stellar mass density increases by a factor of $\sim15_{-6}^{+21}$ from $z=9$ to $z=6$. We estimate the dust-corrected star formation rates (SFRs) to calculate the specific star formation rates ($\mathrm{sSFR}=\mathrm{SFR/M_{*}}$) of our sample, and find that for a fixed stellar mass of $5\times10^{9}M_{\odot}$, sSFR $\propto(1+z)^{2.01\pm0.16}$. Finally, from our new measurements, we estimate the UV luminosity density ($ρ_{\textrm{UV}}$) and find that our results support a smooth decline of $ρ_{\textrm{UV}}$ towards high redshifts.

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