[论文解读] The UNCOVER Survey: A first-look HST+JWST catalog of 60,000 galaxies near Abell 2744 and beyond

John R. Weaver, Sam E. Cutler+42 more|arXiv (Cornell University)|Jan 6, 2023

Astronomy and Astrophysical Research被引用 10

一句话总结

本文介绍了一个公开的 HST+JWST 光度目录，覆盖 Abell 2744 区域约 6 万个对象，具备 PSF 匹配的光度测量、光度红移和放大率估计。

ABSTRACT

In November 2022, the James Webb Space Telescope (JWST) returned deep near-infrared images of Abell 2744 -- a powerful lensing cluster capable of magnifying distant, incipient galaxies beyond it. Together with the existing Hubble Space Telescope (HST) imaging, this publicly available dataset opens a fundamentally new discovery space to understand the remaining mysteries of the formation and evolution of galaxies across cosmic time. In this work, we detect and measure some 60,000 objects across the 49 arcmin$^2$ JWST footprint down to a $5\,σ$ limiting magnitude of $\sim$30 mag in 0.32" apertures. Photometry is performed using circular apertures on images matched to the point spread function of the reddest NIRCam broad band, F444W, and cleaned of bright cluster galaxies and the related intra-cluster light. To give an impression of the photometric performance, we measure photometric redshifts and achieve a $σ_{ m NMAD}\approx0.03$ based on known, but relatively small, spectroscopic samples. With this paper, we publicly release our HST and JWST PSF-matched photometric catalog with optimally assigned aperture sizes for easy use, along with single aperture catalogs, photometric redshifts, rest-frame colors, and individual magnification estimates. These catalogs will set the stage for efficient and deep spectroscopic follow-up of some of the first JWST-selected samples in Summer 2023.

研究动机与目标

• 在 Abell 2744 周围跨 HST 和 JWST 数据提供一个全景式、PSF 匹配、跨多波段的光度目录。
• 降低星系团内光和明亮星系的污染，以恢复背景源的准确光度测量。
• 提供适用于光谱跟踪和透镜研究的光度红移与 rest-frame 颜色。

提出的方法

• 将来自 UNCOVER、GLASS-ERS 和 DD-2756 计划的深度 JWST/NIRCam 成像与 HST 数据结合，创建一个 49 arcmin^2 的覆盖区。
• 使用迭代的 bCG+ICL 建模与遮罩（遵循 Ferrarese 等人 2006 年的 BMODEL/ELLIPSE 方法）来减去亮星团星系和星系团内光。
• 在一个噪声等化、叠加的长波长图像（F277W+F356W+F444W）中使用 SEP 检测天体，并进行 PSF 匹配孔径光度测量。
• 从恒星构建每个滤波的经验 PSF，然后使用 Pypher（基于 Wiener 过滤）建立核基的 PSF 匹配，使之统一到 F444W 参考。
• 在多个圆形孔径（0.32″–1.40″）中提取光度测量，并使用 Kron 基础的修正将其转换为总通量。

Figure 1: Effective catalog depths over the Abell 2744 JWST footprint for the 15 available photometric bands and their transmission curves. The effective depth of our LW detection image is also included. Depths are quoted in 0.32″ diameter apertures and correspond to the area-weighted 50 th (median)

实验结果

研究问题

• RQ1 在透镜簇场合并 HST 和 JWST 成像时，对象目录的产出量和可达到的深度是多少？
• RQ2 去除星系团内光和明亮的星系团星体如何影响光度测量的精度及其得到的光度红移？
• RQ3 在 Abell 2744 背后的探测到的星系群的性质（颜色、红移、放大率）是什么？
• RQ4 PSF 匹配的光度测量在约束高红移星系的 rest-frame 颜色和恒星族群推断方面有多强？

主要发现

• 在 bCG/ICL 减去后，在 JWST 覆盖区的 49 arcmin^2 内检测到 61,648 个源。
• 在可用光谱样本上实现了 NMAD ≈ 0.03 的光度红移精度。
• 将 PSF 匹配到 F444W 在 0.32″孔径时的 PSF 增长曲线偏差<1%，从而实现稳健的颜色测量。
• 该目录提供 HST+JWST 光度测量、光度红移、rest-frame 颜色以及用于后续研究的单独放大率估计。
• 在 0.32″孔径的 5σ 深度在长波段滤镜 F277W、F356W、F444W 的大约 28.5–30.0 mag。

Figure 2: Astrometric performance of the imaging dataset based on positions of bright stars in HST /F160W compared to GAIA DR3. One and four pixel areas are shown by the solid and dashed squares, respectively. Filled purple and grey elliptical contours enclose roughly 50% and 90% of bright stars, re