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arXiv 1706.05063astro-ph.GA
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用不同的JWST宽带滤波器恢复高红移星系的性质

Recovering the properties of high redshift galaxies with different JWST broad-band filters

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

摘要:

詹姆斯·韦伯太空望远镜(JWST)的成像将允许在再电离时期观测大部分遥远星系。其性质的恢复,如年龄,色余E(B-V),比恒星形成率(sSFR)和恒星质量,将主要依赖于光谱能量分布拟合,基于JWST的两个成像相机,即近红外相机(NIRCam)和中红外成像仪(MIRI)提供的数据。在这项工作中,我们分析了选择不同的组合的NIRCam和MIRI宽带滤波器,从0.6 μm到7.7 μm,对这些星系的属性恢复的效果。我们在z=7-10的已知输入属性的1542个模拟星系的样本上进行了测试。我们发现,只有8个宽波段,我们可以恢复星系的年龄在0.1 Gyr和0.06 MAG的颜色过剩的70%的星系。此外,恒星质量和sSFR恢复分别为0.2和0.3 dex,在z=7-9。相反,在z=10时,没有NIRCam波段完全跟踪λ> 4000的区域,恒星质量异常值的百分比(sSFR)与z=9相比增加了> 20%(> 90%)。MIRI F560 W和F770 W波段对于改进恒星质量和z=10时的sSFR估计至关重要。当星云发射线存在时,在任何红移和任何波段组合下,推导正确的星系性质都是具有挑战性的。特别是,恒星质量被系统地高估,平均高达0.3德克斯单独与近红外相机数据,包括MIRI观测仅略有改善的估计。

英文摘要:

Imaging with the James Webb Space Telescope (JWST) will allow for observing the bulk of distant galaxies at the epoch of reionisation. The recovery of their properties, such as age, color excess E(B-V), specific star formation rate (sSFR) and stellar mass, will mostly rely on spectral energy distribution fitting, based on the data provided by JWST's two imager cameras, namely the Near Infrared Camera (NIRCam) and the Mid Infrared Imager (MIRI). In this work we analyze the effect of choosing different combinations of NIRCam and MIRI broad-band filters, from 0.6 μm to 7.7 μm, on the recovery of these galaxy properties. We performed our tests on a sample of 1542 simulated galaxies, with known input properties, at z=7-10. We found that, with only 8 NIRCam broad-bands, we can recover the galaxy age within 0.1 Gyr and the color excess within 0.06 mag for 70% of the galaxies. Besides, the stellar masses and sSFR are recovered within 0.2 and 0.3 dex, respectively, at z=7-9. Instead, at z=10, no NIRCam band traces purely the λ> 4000 Å regime and the percentage of outliers in stellar mass (sSFR) increases by > 20% (> 90%), in comparison to z=9. The MIRI F560W and F770W bands are crucial to improve the stellar mass and the sSFR estimation at z=10. When nebular emission lines are present, deriving correct galaxy properties is challenging, at any redshift and with any band combination. In particular, the stellar mass is systematically overestimated in up to 0.3 dex on average with NIRCam data alone and including MIRI observations improves only marginally the estimation.

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