芝加哥-卡内基哈勃计划：JWST J区渐近巨星分支（JAGB）河外星系距离尺度
The Chicago-Carnegie Hubble Program: The JWST J-region Asymptotic Giant Branch (JAGB) Extragalactic Distance Scale
AI总结：
本文提出一种新算法优化JAGB距离测量位置，并利用JWST NIRCam对7个SN Ia宿主星系进行盲分析，结合CSP样本测得哈勃常数H0=67.80±2.17±1.64 km/s/Mpc，为宇宙学提供独立距离尺度。
摘要：
J区渐近巨星分支（JAGB）方法是一种新的标准烛光，基于J波段碳丰渐近巨星分支星的恒定光度。JAGB方法独立于造父变星和TRGB距离指示器。因此，我们可以利用它来交叉检查造父变星和TRGB距离的系统误差，并用它来测量独立的局部哈勃常数。JAGB方法在测量距离方面相对于TRGB和造父变星还具有许多优势，其中几个优势在与JWST革命性的分辨能力结合时尤为放大。首先，JAGB星在近红外波段比TRGB亮1个星等，并且可以通过单历元近红外测光发现，而造父变星则需要至少12个历元的同步光学成像。因此，使用相同的观测时间，JAGB星可以测量比TRGB星和造父变星远得多的距离。其他优势包括：JAGB星仅通过其颜色和星等即可轻松识别，近红外观测中尘埃消光减少，并且JAGB星在所有具有中等年龄星族的星系中普遍存在。在本文中，我们提出了一种新颖的算法，用于识别星系中应用JAGB方法的最佳位置，以最小化拥挤效应。然后，我们将该算法应用于七颗SN Ia宿主星系的JWST NIRCam成像，以测量其JAGB距离，并进行完全盲分析。该JAGB距离尺度的零点在水 mega-maser 星系NGC 4258中设定。在我们CCHP综述论文Freedman等人（2025）中，我们将本文测量的JAGB距离应用于卡内基超新星计划（CSP）的SN Ia样本，测得哈勃常数H0 = 67.80 +/- 2.17（统计） +/- 1.64（系统） km/s/Mpc。
英文摘要：
The J-region asymptotic giant branch (JAGB) method is a new standard candle based on the constant luminosities of carbon-rich asymptotic giant branch stars in the J band. The JAGB method is independent of the Cepheid and TRGB distance indicators. Therefore, we can leverage it to both cross-check Cepheid and TRGB distances for systematic errors and use it to measure an independent local Hubble constant. The JAGB method also boasts a number of advantages in measuring distances relative to the TRGB and Cepheids, several of which are especially amplified when combined with JWST's revolutionary resolving power. First, JAGB stars are 1 mag brighter in the NIR than the TRGB, and can be discovered from single-epoch NIR photometry unlike Cepheids which require congruent optical imaging in at least 12 epochs. Thus, JAGB stars can be used to measure significantly farther distances than both the TRGB stars and Cepheids using the same amount of observing time. Further advantages include: JAGB stars are easily identified solely via their colors and magnitudes, dust extinction is reduced in near-infrared observations, and JAGB stars are ubiquitous in all galaxies with intermediate-age populations. In this paper, we present a novel algorithm that identifies the optimal location in a galaxy for applying the JAGB method, so as to minimize effects from crowding. We then deploy this algorithm in JWST NIRCam imaging of seven SN Ia host galaxies to measure their JAGB distances, undertaking a completely blind analysis. The zero-point of this JAGB distance scale is set in the water mega-maser galaxy NGC 4258. In our CCHP overview paper Freedman et al. (2025), we apply the JAGB distances measured in this paper to the Carnegie Supernova Program (CSP) SNe Ia sample, measuring a Hubble constant of H0 = 67.80 +/- 2.17 (stat) +/- 1.64 (sys) km/s/Mpc.
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