论文标题
卡内基 - 芝加哥哈勃计划。 ix。 Mega-Maser主机银河系中红色巨型分支方法的校准，NGC4258（M106）
The Carnegie-Chicago Hubble Program. IX. Calibration of the Tip of the Red Giant Branch Method in the Mega-Maser Host Galaxy, NGC4258 (M106)
论文作者
论文摘要
在附近的Galaxy NGC 4258中，H $ _2 $ o Masers围绕其超质量黑洞的良好模块化轨道运动提供了测量精确几何距离的方法。结果，NGC 4258是可用于校准恒星距离指标的真实发光度的几个“几何锚”之一，例如红色巨型分支（TRGB）或Cepheid Leavitt Law的尖端。在本文中，我们介绍了NGC 4258中TRGB在NGC 4258中的明显大小的详细研究，该公共可用的HST沿次要轴线最佳地位于无气和灰尘的光环中，跨越了距离的距离，跨越了距离8至22 kpc的距离，该距离在预测的半径半径中。我们根据对54个Arcmin $^2 $的HST/ACS成像的分析，对与该银河系中的TRGB相关的不确定性进行系统评估。量化这些不确定性后，我们在NGC 4258中测量TRGB为F814W $ _0 $ = 25.347 $ \ pm $ 0.014（STAT）$ \ pm $ 0.042（SYS）MAG。再加上最近1.5％的兆甲板距离NGC 4258的距离，我们确定TRGB的绝对发光度为$ M_ {F814W}^{TRGB} $ = -4.050 $ \ pm $ 0.028（Stat）$ 0.028（stat）$ \ pm $ 0.048（SYS）MAG。在Freedman等人中介绍的独立校准中，这种新的校准同意比1％更好。 （2019，2020），基于位于LMC的脱落要的二进制文件（DEB）。
In the nearby galaxy NGC 4258, the well-modeled orbital motion of H$_2$O masers about its supermassive black hole provides the means to measure a precise geometric distance. As a result, NGC 4258 is one of a few "geometric anchors" available to calibrate the true luminosities of stellar distance indicators such as the Tip of the Red Giant Branch (TRGB) or the Cepheid Leavitt law. In this paper, we present a detailed study of the apparent magnitude of the TRGB within NGC 4258 using publicly-available HST observations optimally situated in the gas- and dust-free halo along the minor axis, spanning distances ranging from 8 to 22 kpc in projected galactocentric radius. We undertake a systematic evaluation of the uncertainties associated with measuring the TRGB in this galaxy, based on an analysis of 54 arcmin$^2$ of HST/ACS imaging. After quantifying these uncertainties, we measure the TRGB in NGC 4258 to be F814W$_0$ = 25.347 $\pm$ 0.014(stat) $\pm$ 0.042(sys) mag. Combined with a recent 1.5% megamaser distance to NGC 4258, we determine the absolute luminosity of the TRGB to be $M_{F814W}^{TRGB}$ = -4.050 $\pm$ 0.028(stat) $\pm$ 0.048(sys) mag. This new calibration agrees to better than 1% with an independent calibration presented in Freedman et al. (2019, 2020) that was based on detached eclipsing binaries (DEBs) located in the LMC.
