论文标题
我们可以如何限制$ z \ sim6-7 $恒星质量功能的低质量端？ - 哈勃边境领域中镜头模型和恒星种群假设的限制
How robustly can we constrain the low-mass end of the $z\sim6-7$ stellar mass function? -- The limits of lensing models and stellar population assumptions in the Hubble Frontier Fields
论文作者
论文摘要
我们介绍了从$ z \ sim6-7 $从静止框架紫外线选出的掉落星系样本中计算出的$ z \ sim6-7 $的Galaxy Stellar质量函数（GSMF）非常低的质量端的新测量。这些星系位于六个哈勃前沿场簇后面，并且都在重力放大。使用深层Spitzer/IRAC和Hubble空间望远镜成像，我们通过拟合星系光谱分布来得出恒星质量，并探索不同模型假设和参数脱发对所得GSMF的影响。我们的样本探针恒星质量降低至$ m _ {\ star}> 10^{6} \，\ text {m} _ {\ odot} $，我们发现$ z \ sim6-7 $ gsmf可以通过修改后的Schechter函数来最佳参数，从而可以在非常低的群众下进行失误。使用GSMF的Monte-Carlo Markov链分析，包括准确的镜头不确定性处理，我们获得了相对较陡的低质量端斜率$α\ simeq-1.96 _ { - 0.08}^{+0.09} $ $ \ log（m_t/\ text {m} _ {\ odot}）\ simeq7.10 _ { - 0.56}^{+0.17} $，曲率为$β\ simeq1.00 _ { - 0.73}^{ - 0.73}^{+0.87} $的曲率均为$β\ simeq1.00 _衰减，$ a_v \ leq0.2 $。我们发现，$ z \ sim6-7 $ gsmf，尤其是其非常低的质量端，受到恒星形成历史的假定功能形式以及恒星质量和尘埃衰减之间的堕落性的显着影响。例如，低质量端坡度范围从$α\ simeq-1.82 _ { - 0.07}^{+0.08} $，对于指数上升的SFH至$α\ simeq-2.34 _ { - 0.10}^{ - 0.10}^{+0.11}^{+0.11} $ a_v $ a_v $ a_v $ a_v $ a_v $ a_v $ a_v $ a_v $ a_v $ a_v $ a _ 3.25 $ 3.25。需要使用James Webb空间望远镜进行更长的波长和更高的角度分辨率的未来观察，以打破这些变性，并在GSMF的极端低质量端上稳健地限制星系的恒星质量。
We present new measurements of the very low-mass end of the galaxy stellar mass function (GSMF) at $z\sim6-7$ computed from a rest-frame ultraviolet selected sample of dropout galaxies. These galaxies lie behind the six Hubble Frontier Fields clusters and are all gravitationally magnified. Using deep Spitzer/IRAC and Hubble Space Telescope imaging, we derive stellar masses by fitting galaxy spectral energy distributions and explore the impact of different model assumptions and parameter degeneracies on the resulting GSMF. Our sample probes stellar masses down to $M_{\star}>10^{6}\,\text{M}_{\odot}$ and we find the $z\sim6-7$ GSMF to be best parametrized by a modified Schechter function which allows for a turnover at very low masses. Using a Monte-Carlo Markov Chain analysis of the GSMF, including accurate treatment of lensing uncertainties, we obtain a relatively steep low-mass end slope $α\simeq-1.96_{-0.08}^{+0.09}$ and a turnover at $\log(M_T/\text{M}_{\odot})\simeq7.10_{-0.56}^{+0.17}$ with a curvature of $β\simeq1.00_{-0.73}^{+0.87}$ for our minimum assumption model with constant star-formation history (SFH) and low dust attenuation, $A_V\leq0.2$. We find that the $z\sim6-7$ GSMF, in particular its very low-mass end, is significantly affected by the assumed functional form of the star formation history and the degeneracy between stellar mass and dust attenuation. For example, the low-mass end slope ranges from $α\simeq-1.82_{-0.07}^{+0.08}$ for an exponentially rising SFH to $α\simeq-2.34_{-0.10}^{+0.11}$ when allowing $A_V$ of up to 3.25. Future observations at longer wavelengths and higher angular resolution with the James Webb Space Telescope are required to break these degeneracies and to robustly constrain the stellar mass of galaxies on the extreme low-mass end of the GSMF.
