用 JWST 对距离阶梯星系中 J 区渐近巨星支的侦察：从不规则光度函数到哈勃常数的近似
Reconnaissance with JWST of the J-region Asymptotic Giant Branch in Distance Ladder Galaxies: From Irregular Luminosity Functions to Approximation of the Hubble Constant
AI总结：
本文利用 JWST NIRCam 研究距离阶梯星系中 JAGB 恒星，比较多方法测得的参考星等并发现光度函数不对称导致约 0.19 mag 差异，最终得到哈勃常数基准值 74.7 km/s/Mpc。
摘要：
我们研究脉泽宿主 NGC 4258 和 4 个 Ia 型超新星（SN Ia）宿主（NGC 1448、NGC 1559、NGC 5584 和 NGC 5643）的近红外颜色-星等图中渐近巨星支 J 区（JAGB）的恒星。利用詹姆斯·韦布空间望远镜（James Webb Space Telescope）NIRCam 测光，这些恒星团块在 $1.0<F150W-F277W<1.5$ 和 $m_{F150W}$=22-25 mag 附近清晰可见。针对这一新近提出的标准烛光，已提出多种方法来确定其视参考星等，包括众数、中位数、sigma 裁剪均值或模型化光度函数参数。我们通过测量宿主内部变化来检验这些方法的一致性，发现差异可达约 0.2 mag，显著超过统计不确定度。亮度差异似乎是内禀的，并进一步被 JAGB 光度函数的非均匀形状放大，这种非均匀形状在大麦哲伦云（LMC）和小麦哲伦云（SMC）中也很明显。我们采用“多方法”途径，以 NGC 4258 为定标，一致地测量 JAGB 星等和到 SN Ia 宿主样本的距离。我们发现与造父变星、红巨星支尖端（TRGB）和 Mira 变星测得的距离具有广泛一致性。然而，通过 JAGB 方法估计 $H_0$ 所需的 SN 宿主平均距离在上述定义之间相差约 0.19 mag，这是光度函数不对称程度不同的结果。这些方法给出的完整范围为 $71-78$ km s$^{-1}$ Mpc$^{-1}$，即基准结果为 $H_0=74.7\pm2.1$（统计）$\pm2.3$（系统）（若按平方和合成则为 $\pm3.1$）km s$^{-1}$ Mpc$^{-1}$，系统误差受方法间差异的限制。未来工作可进一步标准化和精化这一有前景的工具，使其与既有距离指标相比更具竞争力。
英文摘要：
We study stars in the J-regions of the asymptotic giant branch (JAGB) of near-infrared color magnitude diagrams in the maser host NGC 4258 and 4 hosts of 6 Type Ia supernovae (SN Ia): NGC 1448, NGC 1559, NGC 5584, and NGC 5643. These clumps of stars are readily apparent near $1.0<F150W-F277W<1.5$ and $m_{F150W}$=22-25 mag with James Webb Space Telescope NIRCam photometry. Various methods have been proposed to assign an apparent reference magnitude for this recently proposed standard candle, including the mode, median, sigma-clipped mean or a modeled luminosity function parameter. We test the consistency of these by measuring intra-host variations, finding differences of up to $\sim$0.2 mag that significantly exceed statistical uncertainties. Brightness differences appear intrinsic, and are further amplified by the non-uniform shape of the JAGB luminosity function, also apparent in the LMC and SMC. We follow a 'many methods' approach to consistently measure JAGB magnitudes and distances to the SN Ia host sample calibrated by NGC 4258. We find broad agreement with distances measured from Cepheids, tip of the red giant branch (TRGB), and Miras. However, the SN host mean distance estimated via the JAGB method necessary to estimate $H_0$ differs by $\sim$0.19 mag amongst the above definitions, a result of different levels of luminosity function asymmetry. The methods yield a full range of $71-78$ km s$^{-1}$ Mpc$^{-1}$, i.e., a fiducial result of $H_0=74.7\pm2.1$ (stat) $\pm$2.3 (sys) ($\pm$3.1 if combined in quadrature) km s$^{-1}$ Mpc$^{-1}$, with systematic errors limited by the differences in methods. Future work may seek to further standardize and refine this promising tool, making it more competitive with established distance indicators.
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。
