[论文解读] The Herschel/PACS Point Source Catalogue Explanatory Supplement

G. Marton, L. Calzoletti+7 more|arXiv (Cornell University)|May 16, 2017

Calibration and Measurement Techniques被引用 23

一句话总结

本论文介绍了赫歇尔/PACS点源星表（HPPSC），该星表基于13,000多张PACS图像生成，覆盖70、100和160 μm波段，共包含108,319至251,392个可靠的点源，使用HIPE和SUSSEXtractor处理。星表在深外星系场中达到90%的完整度，对应约30 mJy的流量水平，且与校准星的测光精度在1%以内，与Hi-GAL等外部星表的流量一致性在10%以内。

ABSTRACT

The Herschel Space Observatory was the fourth cornerstone mission in the European Space Agency (ESA) science programme. It had excellent broad band imaging capabilities in the far-infrared (FIR) and sub-millimetre part of the electromagnetic spectrum. Although the spacecraft finished observing in 2013, it left a large legacy dataset that is far from having been fully explored and still has a great potential for new scientific discoveries. The PACS and SPIRE photometric cameras observed about 8% of the sky in six different wavebands. This document describes the Herschel/PACS Point Source Catalogue (HPPSC), a FIR catalogue based on the broad-band photometric observations of the PACS instrument with filters centred at 70, 100 and 160 microns. We analysed 14842 combined, Level 2.5/Level 3 Herschel/PACS photometric observations. The PACS photometer maps were generated by the JScanam task of the Herschel Interactive Processing Environment (HIPE) v13.0.0. Sources were identified with the HIPE implementation of SUSSEXtractor, and the flux densities obtained by aperture photometry. We found a total of 108 319 point sources that are considered to be reliable in the 70 micron maps, 131 322 at 100 micron and 251 392 point sources in the 160 micron maps. In addition, our quality control algorithm identified 546 587 candidate sources that were found to be extended and 7 185 160 features which did not pass the signal-to-noise and other criteria to be considered reliable sources. These sources were included in the Extended Source List and Rejected Source List of the HPPSC, respectively. The calculated completeness and photometric accuracy values are based on simulations, where artificial sources were injected into the observational timeline with well controlled flux density values. The actual completeness is a complex function of the source flux, photometric band and the background complexity.

研究动机与目标

• 从赫歇尔/PACS在70、100和160 μm波段的远红外测光数据中，创建一个可靠且公开可访问的点源星表。
• 通过结构噪声和背景RMS指标的严格源检测与质量控制，确保高测光精度和位置可靠性。
• 通过模拟和与Hi-GAL、PEP-COSMOS等外部巡天的交叉匹配，验证星表的完整度和测光精度。
• 为HPPSC数据产品提供标准化、自包含的说明补充材料，确保天文学界一致使用。
• 识别并分类扩展源与被拒绝的源，提升星表在复杂源环境中的实用性。

提出的方法

• 使用HIPE v13.0.0中的JScanam任务，从Level 2.5/Level 3数据生成13,000多张PACS图像，包括标准、并行和太阳系天体（SSO）观测。
• 利用HIPE中实现的SUSSEXtractor进行源检测，通过孔径测光测量流量密度。
• 应用结构噪声（S/N S）和背景RMS（S/N R）指标，评估源的可靠性与信噪比。
• 通过二维高斯拟合估计源的FWHM和拉伸度，标记边缘效应、源混合及热姿态影响。
• 通过人工源模拟估算在不同背景复杂度下的完整度与测光精度。
• 通过清洗检测结果、解决多重检测问题，并基于观测和位置信息分配唯一ID，整合源表。

实验结果

研究问题

• RQ1 HPPSC在不同测光波段和背景复杂度下的完整度极限是什么？
• RQ2 与已知校准标准和外部巡天相比，HPPSC的测光精度如何？
• RQ3 复杂区域中的扩展发射对弱点源检测的影响程度如何？
• RQ4 HPPSC中的S/N指标（S/N S和S/N R）与Hi-GAL等其他巡天相比如何？
• RQ5 HPPSC源的位置精度相对于模拟中的输入位置如何？

主要发现

• HPPSC包含108,319个70 μm可靠源，131,322个100 μm源，251,392个160 μm源，另有546,587个扩展源和7,185,160个被拒绝的特征。
• 在深外星系场中，90%完整度达到约30 mJy，但在复杂区域因扩展发射引起的混淆，仅在约1 Jy水平实现。
• 测光精度与校准星相比在1%以内，与Hi-GAL流量相比在~10%以内，流量比值的离散度约为25–30%。
• 位置精度在标称指向误差范围内，且与PSF FWHM一致，经模拟验证确认。
• 星表恢复了外部外星系星表中约50%的源，以及银河系平面巡天中约20–30%的源，可能因点源分类标准更偏好紧凑形态。
• S/N S与S/N R值在红波段与Hi-GAL表现良好一致，但HPPSC的S/N S在蓝波段覆盖范围更广，表明对局部噪声结构更敏感。