利用SPHEREx观测比较不同恒星群体合成模型的近红外光谱能量分布
Comparing the Near-infrared Spectral Energy Distributions from Different Stellar Population Synthesis Models with SPHEREx Observations
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中文总结 AI 辅助
该研究利用SPHEREx观测数据，比较SDSS致密星系的近红外光谱能量分布与四种恒星群体合成模型预测结果，发现模型在近红外存在高估或低估问题，强调完善模型中近红外恒星光谱特征的必要性。
中文摘要 AI 辅助
恒星群体合成（SPS）模型在光学波长光谱分析中广泛应用，但近红外（NIR）特性因观测光谱相对缺乏仍不确定。SPHEREx分光光度数据波长覆盖0.7 - 5.0μm，适合研究SPS模型在NIR的性能。本文将SDSS致密星系的SPHEREx观测数据与SDSS光学光谱全谱拟合预测的NIR SEDs比较，使用四种延伸至NIR的SPS模型。发现所有模型在2.4 - 5μm处倾向于高估恒星连续谱0.1 - 0.3星等，该趋势在中等年龄恒星群体中尤其突出。对于年龄大于5Gyr的恒星群体，E - MILES在3.8 - 5μm处偏移相对较小。对于发射线星系，由于非恒星发射贡献，SPS模型在较长波长低估SED达0.5星等。这些结果凸显完善SPS模型中NIR恒星光谱特征的必要性。
英文摘要
While stellar population synthesis (SPS) models have been widely used for spectral analysis in optical wavelengths, their characteristics remain uncertain in the near-infrared (NIR) due to a relative lack of observed NIR spectra. The spectrophotometric data from SPHEREx are well-suited for investigating the performance of SPS models in the NIR, thanks to its wide wavelength coverage over $0.75-5.0~{\rm μm}$. In this work, we compare the observed SPHEREx data of SDSS compact galaxies, including 2,726 non-emission-line galaxies and 1,163 emission-line galaxies, to the NIR SEDs predicted from the full spectrum fitting of SDSS optical spectra. We use four different SPS models that extend into the NIR: E-MILES, Bruzual \& Charlot (BC03), Charlot \& Bruzual (CB19), and FSPS. We find that all four models tend to overpredict the stellar continuum at $2.4-5~{\rm μm}$ by $0.1-0.3~{\rm mag}$. This trend is particularly prominent for intermediate-age stellar populations ($\sim1-5~{\rm Gyr}$), suggesting a systematic bias in the NIR SED predictions of current SPS models. For stellar populations older than $5~{\rm Gyr}$, E-MILES shows relatively smaller offsets at $3.8-5~{\rm μm}$ compared to other models. Meanwhile, for emission-line galaxies, the SPS models underestimate the SED by up to $\sim0.5~{\rm mag}$ at longer wavelengths due to the contribution of non-stellar emission. Overall, these results highlight the necessity of refining the NIR stellar spectral features in SPS models, such as emissions from thermally pulsating asymptotic giant branch stars or molecular absorptions from cool stars.
发表机构
- Research Institute of Basic Sciences, Seoul National University（首尔大学基础科学研究院）
- Seoul National University（首尔大学）
- Yonsei University（延世大学）
- Korea Astronomy and Space Science Institute（韩国天文与空间科学研究所）
- IPAC, California Institute of Technology（加州理工学院IPAC）
- Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
- California Institute of Technology（加州理工学院）
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