论文标题
JWST NIRCAM+NIRSPEC：年轻星系的星际培养基和恒星种群，具有上升的恒星形成和不断发展的气体储层
JWST NIRCam+NIRSpec: Interstellar medium and stellar populations of young galaxies with rising star formation and evolving gas reservoirs
论文作者
论文摘要
我们提出了三种光谱镜的星际培养基和恒星种群分析，该媒体镜面确认了$ z> 7 $的星系，在ERO JWST NIRCAM和SMACS J0723.3-7327群集的JWST NIRCAM和JWST NIRSPEC数据中。我们使用具有灵活的恒星形成历史记录（SFH），可变的灰尘衰减定律以及Nebular发射（连续和排放线）的自吻合模型的贝叶斯光谱拟合代码\ Texttt {procector}。重要的是，考虑到缝隙效应，我们自言自语地符合JWST NIRSPEC的发射线通量和JWST Nircam的宽带光度法。我们发现，这三美元的Z = 7.6-8.5 $星系（$ M _ {\ star} \ lot10^{8} 〜M _ {\ odot} $）年轻，SFHS的上升和大规模加权年龄为$ 3-4 $，尽管我们找到了基础较老Stellar stellar stellar stellarar sellar sellar sellar sellar sellar的指示。推断的气相金属性与极光线的直接金属性估计广泛一致。具有最低气相金属性的星系（$ \ Mathrm {Z} _ {\ rm Gas} = 0.06〜\ Mathrm {Z} _ {\ odot} $）的SFH急剧上升，非常紧凑（$ <0.2〜 \ m atrm {kpc} $） （$σ_ {\ rm sfr} \ oft22〜 \ mathrm {m} _ {\ odot}〜\ mathrm {yr}^{ - 1}〜\ mathrm {kpc}^{kpc}^{ - 2} $）具有较高气相金属性的其他两个对象在KPC尺度上显示出更复杂的多组分形态，表明它们最近的恒星形成率的增加是由合并或内部重力不稳定性驱动的。我们讨论假设不同的SFH先验或仅拟合光度数据的效果。我们的分析强调了结合JWST成像和光谱法的强度和重要性，以充分评估最早时代的星系性质。
We present an interstellar medium and stellar population analysis of three spectroscopically confirmed $z>7$ galaxies in the ERO JWST NIRCam and JWST NIRSpec data of the SMACS J0723.3-7327 cluster. We use the Bayesian spectral energy distribution (SED) fitting code \texttt{Prospector} with a flexible star-formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST NIRSpec and the broad-band photometry from JWST NIRCam, taking into account slit-loss effects. We find that these three $z=7.6-8.5$ galaxies ($M_{\star}\approx10^{8}~M_{\odot}$) are young with rising SFHs and mass-weighted ages of $3-4$ Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity ($\mathrm{Z}_{\rm gas}=0.06~\mathrm{Z}_{\odot}$) has a steeply rising SFH, is very compact ($<0.2~\mathrm{kpc}$) and has a high star-formation rate surface density ($Σ_{\rm SFR}\approx22~\mathrm{M}_{\odot}~\mathrm{yr}^{-1}~\mathrm{kpc}^{-2}$), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicity show more complex multi-component morphologies on kpc scales, indicating that their recent increase in star-formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.
