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arXiv 1906.05320astro-ph.GA
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用JWST宽带滤波器观测的高z星系由于模板简并引起的统计恒星质量修正

Statistical stellar mass corrections for high-z galaxies observed with JWST broad-band filters due to template degeneracies

L. Bisigello, K. I. Caputi, L. Colina, P. G. Pérez-González, A. Koekemoer, O. Le Fèvre, N. Grogin, H. U. Nørgaard-Nielsen, P. van der Werf

摘要:

未来的詹姆斯·韦伯空间望远镜(JWST)深空场中的恒星质量将主要通过用理论星系模板拟合光谱能量分布来获得。我们研究了用LePhare光谱能量分布拟合程序和Yggdrasil理论模板计算恒星质量的不确定性和偏差。我们考虑一个样本的模拟星系在z $=$ 7-10模拟JWST观测与S/N $_{F150W}\geqslant$ 10。我们的目标是提供一个统计恒星质量校正列表,包括不同输出星系属性和JWST滤波器组合的恒星质量推导,以校正模板简并。统计恒星质量修正的中位数从-0.83 dex到0.87 dex不等,而25 $\%$(75 $\%$)四分位数从-0.83 dex(-0.67 dex)到0.51 dex(0.88 dex)不等,这取决于滤波器组合和星系模型。最具挑战性的情况是具有星云发射线的星系,特别是那些被错误地识别为没有相对无尘星系和具有小金属丰度的星系(即Z $=1/50Z_{\odot}$)的星系。在没有发射谱线的情况下,对星系的恒星质量估计通常是正确的,除了在z $=$ 10时只考虑8个NIRCam波段,这使得MIRI波段非常有价值。利用公开的JAGUAR星系表对我们的恒星质量修正进行了检验,得到修正后的恒星质量分布在z $>$ 7处的平均偏差减小了20-50 $\%$。我们发现,在没有恒星质量修正的情况下,低质量星系(M $^{*}<10^{7}M_{\odot}$)的数目被高估了,这可能导致在计算高z处星系恒星质量函数暗端斜率时产生系统误差.

英文摘要:

Stellar masses in future James Webb Space Telescope (JWST) deep blank-fields will be mainly derived fitting the spectral energy distribution with theoretical galaxy templates. We investigate the uncertainties and biases of the stellar masses derived by using the LePhare code for spectral energy distribution fitting and the Yggdrasil theoretical templates. We consider a sample of mock galaxies at z$=$7-10 with mock JWST observations with S/N$_{F150W}\geqslant$ 10. Our goal is to provide a list of statistical stellar mass corrections to include on the stellar mass derivation for different output galaxy properties and JWST filter combinations to correct for template degeneracies. Median statistical stellar mass corrections vary from -0.83 dex to 0.87 dex, while 25$\%$ (75$\%$) quartiles range from -0.83 dex (-0.67 dex) to 0.51 dex (0.88 dex), depending on filter combinations and galaxy models. The most challenging cases are galaxies with nebular emission lines, especially the ones that are wrongly identified as galaxies without, relative dust-free galaxies and galaxies with small metallicities (i.e. Z$=1/50Z_{\odot}$). The stellar mass estimation of galaxies correctly identified without emission lines is generally fine, except at z$=$10 when considering only the 8 NIRCam bands, which make the MIRI bands very valuable. We have tested our stellar mass corrections using the public JAGUAR galaxy catalogue, deriving that the average discrepancy in the recovered stellar mass distribution decreases by 20-50$\%$ at z$>$7 after the correction. We found that without the stellar-mass corrections the number of low-mass galaxies (M$^{*}<10^{7}M_{\odot}$) is overestimated, which can potentially lead to systematic errors in the calculation of the galaxy stellar mass function faint-end slope at high z.

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