TONGS: A Treasury of Nearby Galaxy Surveys

Abstract

The beginning of the 21st century marked the “modern era of galaxy surveys” in astronomy. Rapid innovation in observing technology, combined with the base built by galaxy catalogs and atlases dating back centuries, sparked an explosion of new observational programs driven by efforts to understand the different processes driving galaxy evolution. This review aims to answer the following science questions: (1) how have galaxy surveys evolved in the past 20 yr, and how have traditional observational programs been affected by the rise of large panoramic surveys, (2) can the term “nearby” be quantified in the context of galaxy surveys, and (3) how complete is the coverage of the nearby universe and what areas hold the largest opportunity for future work? We define a galaxy survey as a systematically obtained data set which aims to characterize a set of astronomical objects. Galaxy surveys can further be subdivided based on the methods used to select the objects to observe, the properties of the survey samples (e.g., distance or morphology), or the observing strategies used. We focus on pointed nearby galaxy surveys, which we define as surveys which observe a specific sample of target galaxies. Through a study of 43 nearby galaxy surveys, we find no standardized quantitative definition for “nearby” with surveys covering a wide range of distances. We observe that since 2003, traditional targeted galaxy surveys have undergone a dramatic evolution, transitioning from large, statistical surveys to small, ultra-specific projects which compliment the rise of large high resolution panoramic surveys. While wavelength regimes observable from the ground (such as radio or optical wavelengths) host numerous surveys, the largest opportunity for future work is within the less covered space-based wavelength regimes (especially ultraviolet and X-ray).