北银极远紫外漫射辐射作为银河系消光的示踪物
Far-Ultraviolet diffuse emission as a tracer of Galactic extinction at the North Galactic Pole
- Tezpur University（特佐普尔大学）
- Manipal Academy of Higher Education（马尼帕尔高等教育学院）
- Indian Institute of Astrophysics（印度天体物理研究所）
- Institute of Astronomy, 48 Pyatnitskaya St., Moscow 119017, Russia（俄罗斯莫斯科彼特尼茨卡亚街48号天文研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用GALEX远紫外漫射辐射构建北银极高分辨率消光图，通过质心拟合法克服噪声，验证其与Planck及类星体消光高度一致，可作为热尘埃消光图的替代方案。
AI中文摘要：
高银纬处的星际消光通常通过热尘埃辐射来示踪，但从红外表面亮度到红化的转换对尘埃颗粒性质和温度敏感。我们测试了尘埃散射的远紫外（FUV）和近紫外（NUV）漫射辐射，作为北银极（NGP）方向的高分辨率消光示踪物，该方向E(B-V) < 0.1星等。利用Murthy（2014）的GALEX漫射图，我们在b > 70度的区域内构建了6角分分辨率的FUV和NUV强度图，并将其与匹配分辨率下的Planck E(B-V)图进行比较。直接的像素对像素回归仅给出中等相关性（FUV为rho = 0.536，NUV为0.243），这是由于H2荧光、发射线和光子计数噪声造成的高每像素散点；因此，我们构建了每像素的GALEX不确定度图，并应用质心拟合方法，在通过迭代sigma裁剪剔除异常值后，拟合E(B-V)分箱中的平均强度，恢复了紧密关系（FUV为rho = 0.993，NUV为0.976）。我们发现每个6'x6'像素的FUV和NUV强度的最佳拟合关系为：FUV = 2285.3 E(B-V) + 278.6 和 NUV = 1517.6 E(B-V) + 547.2（光子/厘米^2/秒/球面度/埃），反转后生成601x601的GALEX红化图。GALEX E(B-V)与全天HI4PI巡天的HI柱密度强相关（rho = 0.991）。我们使用SDSS类星体作为河外消光校准器验证了这些图：来自GALEX和Planck图的类星体消光以0.99的相关性和0.986的斜率一致。与Schlafly等人（2014）的Pan-STARRS1恒星红化图比较显示，基于GALEX的值具有更小的平均差异（0.039星等），而基于Planck的值为0.064星等。这些结果确立了尘埃散射的FUV漫射辐射作为高银纬处热尘埃消光图的可行替代方案。
英文摘要：
Interstellar extinction at high Galactic latitude is often traced by thermal dust emission, but the conversion from infrared surface brightness to reddening is sensitive to grain properties and temperature. We test dust-scattered far-ultraviolet (FUV) and near-ultraviolet (NUV) diffuse emission as a high-resolution extinction tracer towards the North Galactic Pole (NGP), where E(B-V) < 0.1 mag. Using the GALEX diffuse maps of Murthy (2014), we build FUV and NUV intensity maps at 6' resolution over the region b > 70 deg and compare them with the Planck E(B-V) map at matched resolution. A direct pixel-to-pixel regression gives only moderate correlations (rho = 0.536 for FUV, 0.243 for NUV) owing to high per-pixel scatter from H2 fluorescence, line emission, and photon-counting noise; we therefore construct per-pixel GALEX uncertainty maps and apply a centroid-fitting method that fits the mean intensity in bins of E(B-V) after rejection of outliers via iterative sigma-clipping, recovering tight relations (rho = 0.993 for FUV, 0.976 for NUV). We find the best-fit relations for the FUV and NUV intensity per 6'x6' pixel: FUV = 2285.3 E(B-V) + 278.6 and NUV = 1517.6 E(B-V) + 547.2 (photons/cm^2/s/sr/A), inverted to produce a 601x601 GALEX reddening map. GALEX E(B-V) correlates strongly with HI column density from the all-sky HI4PI survey (rho = 0.991). We validate the maps using SDSS quasars as extragalactic extinction calibrators: quasar extinctions from the GALEX and Planck maps agree with a correlation of 0.99 and a slope of 0.986. Comparison with the Pan-STARRS1 stellar reddening map of Schlafly et al. (2014) shows the GALEX-based values have a smaller mean difference (0.039 mag) than the Planck-based values (0.064 mag). These results establish dust-scattered FUV diffuse emission as a viable alternative to thermal-dust extinction maps at high Galactic latitude.
