Sky Subtraction in an Era of Low Surface Brightness Astronomy

Abstract

The Vera C. Rubin Observatory Wide-Fast Deep (WFD) sky survey will reach unprecedented surface brightness depths over tens of thousands of square degrees. Surface brightness photometry has traditionally been a challenge. Current algorithms which combine object detection with sky estimation systematically over-subtract the sky, biasing surface brightness measurements at the faint end and destroying or severely compromising low surface brightness light. While it has recently been shown that properly accounting for undetected faint galaxies and the wings of brighter objects can in principle recover a more accurate sky estimate, this has not yet been demonstrated in practice. Obtaining a consistent spatially smooth underlying sky estimate is particularly challenging in the presence of representative distributions of bright and faint objects. In this paper we use simulations of crowded and uncrowded fields designed to mimic Hyper Suprime-Cam data to perform a series of tests on the accuracy of the recovered sky. Dependence on field density, galaxy type and limiting flux for detection are all considered. Several photometry packages are utilised: Source Extractor, Gnuastro, and the LSST Science Pipelines. Each is configured in various modes, and their performance at extreme low surface brightness analysed. We find that the combination of the Source Extractor software package with novel source model masking techniques consistently produce extremely faint output sky estimates, by up to an order of magnitude, as well as returning high fidelity output science catalogues.

Accepted for publication in MNRAS. 41 pages: 9 figures and 1 table in the main text, 11 figures and 2 tables in the appendix

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Cited by in corpus (7)

• Dissecting the RELICS cluster SPT-CLJ0615-5746 through the intracluster light: confirmation of the multiple merging state of the cluster formation
• Strategies for optimal sky subtraction in the low surface brightness regime
• Extragalactic Stellar Tidal Streams in the Dark Energy Survey
• A giant thin stellar stream in the Coma Galaxy Cluster
• A Recipe for Unbiased Background Modeling in Deep Wide-Field Astronomical Images
• The Intracluster Light of Abell 3667: Unveiling an Optical Bridge in LSST Precursor Data
• Bright Star Subtraction Pipeline for LSST: Phase one report