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arXiv 2406.04437astro-ph.GA
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距峰顶尚有半途:JWST MIRI 5.6微米计数与源族群

Halfway to the Peak: The JWST MIRI 5.6 micron number counts and source population

Leonid Sajkov, Anna Sajina, Alexandra Pope, Stacey Alberts, Lee Armus, Duncan Farrah, Jamie Lin, Danilo Marchesini, Jed McKinney, Sylvain Veilleux, Lin Yan, Jason Young

AI总结:

本研究分析JWST MIRI 5.6微米深场图像,得到更显著拐点的源计数,明确源的红移与质量分布,补充COSMOS2020源的中红外数据,并发现一批未收录的尘埃星系。

摘要:

我们对8幅詹姆斯·韦伯空间望远镜(JWST)中红外仪器(MIRI)5.6微米图像开展分析,其5σ探测深度约为0.1微央(uJy)。在18.4平方角分的合并天区中,我们共探测到2854个源。我们计算了MIRI 5.6μm的源计数,并分析了天区间的差异。与已发表的早期MIRI 5.6μm计数结果相比,本研究的计数在约2微央处呈现出更显著的拐点。该拐点处计数的位置和幅值与Cowley等人(2018)的模型预测一致,但这些模型往往会高估拐点以下的计数结果。在重叠天区中,84%的MIRI源能在COSMOS2020星表中找到对应体。这些MIRI源的红移大多处于z~0.5-2区间,还有一个延伸至z~5的尾部。它们主要是中等至低恒星质量(10^8-10^10倍太阳质量M⊙)的主序恒星形成星系,这表明经过约2小时的曝光,MIRI能够探测到宇宙正午时期远低于特征星系质量M*的星系,还能探测到红移z~5处的更大质量系统。重叠天区内近70%的COSMOS2020源现在拥有了5.6μm(对应宇宙正午时期的静止帧近红外波段)的观测数据点,这有助于更准确地估算恒星族群参数。最后,我们发现了31个未被COSMOS2020收录的MIRI亮源。通过与红外阵列相机(IRAC)1通道的交叉匹配表明,其中10-20%可能是较低质量(恒星质量M_*≈10^9倍太阳质量)、红移z~1的尘埃星系。其余80-90%则与红移z>3处质量更大但仍含大量尘埃的星系相符。

英文摘要:

We present an analysis of eight JWST Mid-Infrared Instrument (MIRI) 5.6 micron images with $5\,σ$ depths of ~0.1 uJy. We detect 2854 sources within our combined area of 18.4 square arcminutes. We compute the MIRI 5.6um number counts including an analysis of the field-to-field variation. Compared to earlier published MIRI 5.6 um counts, our counts have a more pronounced knee, at roughly 2 uJy. The location and amplitude of the counts at the knee are consistent with the Cowley et al. (2018) model predictions, although these models tend to overpredict the counts below the knee. In areas of overlap, 84% of the MIRI sources have a counterpart in the COSMOS2020 catalog. These MIRI sources have redshifts that are mostly in the $z\sim0.5-2$, with a tail out to $z\sim5$. They are predominantly moderate to low stellar masses ($10^8-10^{10}$M$_{\odot}$) main sequence star-forming galaxies, suggesting that with ~2hr exposures, MIRI can reach well below $M^*$ at cosmic noon and reach higher mass systems out to $z\sim5$. Nearly 70% of the COSMOS2020 sources in areas of overlap now have a data point at 5.6um (rest-frame near-IR at cosmic noon) which allows for more accurate stellar population parameter estimates. Finally, we discover 31 MIRI-bright sources not present in COSMOS2020. A cross-match with IRAC channel 1 suggests that 10-20% of these are likely lower mass (M$_*\approx10^9$M$_{\odot}$), $z\sim1$ dusty galaxies. The rest (80--90%) are consistent with more massive but still very dusty galaxies at $z>3$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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