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arXiv 2312.03060astro-ph.GA
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JWST分辨恒星族群早期发布科学计划 IV:本星系群星系WLM的恒星形成历史

The JWST Resolved Stellar Populations Early Release Science Program IV: The Star Formation History of the Local Group Galaxy WLM

Kristen. B. W. McQuinn, Max J. B. Newman, Alessandro Savino, Andrew E. Dolphin, Daniel R. Weisz, Benjamin F. Williams, Martha L. Boyer, Roger E. Cohen, Matteo C… 展开作者

Kristen. B. W. McQuinn, Max J. B. Newman, Alessandro Savino, Andrew E. Dolphin, Daniel R. Weisz, Benjamin F. Williams, Martha L. Boyer, Roger E. Cohen, Matteo Correnti, Andrew A. Cole, Marla C. Geha, Mario Gennaro, Nitya Kallivayalil, Karin M. Sandstrom, Evan D. Skillman, Jay Anderson, Alberto Bolatto, Michael Boylan-Kolchin, Christopher T. Garling, Karoline M. Gilbert, Leo Girardi, Jason S. Kalirai, Alessandro Mazzi, Giada Pastorelli, Hannah Richstein, Jack T. Warfield

AI总结:

研究利用JWST NIRCam分辨恒星族群首次恢复本星系群星系WLM的SFH与AMR,并通过HST和光谱交叉验证,揭示其早发、长期暂停后再点燃的形成过程。

摘要:

我们展示了利用JWST NIRCam仪器拍摄的分辨恒星族群所得到的首个恒星形成历史(SFH)和年龄—金属丰度关系(AMR)。目标是位于970 kpc处的本星系群恒星形成星系WLM。颜色—星等图(CMD)的深度达到最古老主序拐折点以下,在M_F090W=+4.6星等处SNR=10;这是所有非银河系卫星星系中最深的CMD。我们使用与NIRCam观测重叠的哈勃空间望远镜(HST)光学成像,直接评估基于这两台伟大天文台数据得到的SFH。基于JWST和HST的SFH高度一致。我们利用由恒星光谱测得的金属丰度分布函数,确认了基于JWST数据的AMR趋势。总之,这些结果证实了使用NIRCam F090W–F150W滤光片组合恢复SFH和AMR的有效性,并验证了近红外恒星演化库相对于光学库在SFH恢复工作中的灵敏度和准确性。从JWST数据来看,WLM表现出较早开始恒星形成,随后在再电离之后经历了一段漫长的暂停,之后恒星形成重新点燃;这在定性上类似于在孤立星系Leo A和Aquarius中观测到的情况。在定量上,15%的恒星质量形成于最初1 Gyr,而在接下来约5 Gyr中仅形成10%;随后恒星质量在约2.5 Gyr内迅速翻倍,并在最近约5 Gyr中保持持续恒星形成。

英文摘要:

We present the first star formation history (SFH) and age-metallicity relation (AMR) derived from resolved stellar populations imaged with the JWST NIRCam instrument. The target is the Local Group star-forming galaxy WLM at 970 kpc. The depth of the color-magnitude diagram (CMD) reaches below the oldest main sequence turn-off with a SNR=10 at M_F090W=+4.6 mag; this is the deepest CMD for any galaxy that is not a satellite of the Milky Way. We use Hubble Space Telescope (HST) optical imaging that overlaps with the NIRCam observations to directly evaluate the SFHs derived based on data from the two great observatories. The JWST and HST-based SFHs are in excellent agreement. We use the metallicity distribution function measured from stellar spectra to confirm the trends in the AMRs based on the JWST data. Together, these results confirm the efficacy of recovering a SFH and AMR with the NIRCam F090W-F150W filter combination and provide validation of the sensitivity and accuracy of stellar evolution libraries in the near-infrared relative to the optical for SFH recovery work. From the JWST data, WLM shows an early onset to star formation, followed by an extended pause post-reionization before star formation re-ignites, which is qualitatively similar to what has been observed in the isolated galaxies Leo~A and Aquarius. Quantitatively, 15% of the stellar mass formed in the first Gyr, while only 10% formed over the next ~5 Gyr; the stellar mass then rapidly doubled in ~2.5 Gyr, followed by constant star formation over the last ~5 Gyr.

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