Wide-field multiwavelength surveys from gamma rays to radio wavelengths have revolutionized our understanding of the growth and evolution of galaxies and their supermassive black holes, and one key…

Dartmouth College's Office of Sponsored Projects was awarded a $301,150 grant from the National Aeronautics and Space Administration (NASA) under the Astrophysics Data Analysis Program (ADAP). The grant will fund the development and utilization of tools to perform X-ray stacking analyses of the entire NASA's NuSTAR and Chandra X-ray archives. This will enable the research team to dramatically extend the knowledge of X-ray properties of source populations detected in wide-area surveys from ultraviolet to far-infrared wavelengths, such as GALEX, 2MASS, Spitzer, WISE, and Herschel. The project aims to adapt the existing StackFAST software package, release stacked X-ray databases and analysis code publicly, and develop web-based tools to allow end users to leverage the extensive data sets and the full NuSTAR and Chandra archives. This award does not include a set-aside designation.

Wide-field multiwavelength surveys from gamma rays to radio wavelengths have revolutionized our understanding of the growth and evolution of galaxies and their supermassive black holes, and one key component has been observations in x-rays (for reviews see e.g., brandt & alexander 2015 and hickox & alexander 2018). Despite these successes, a major limitation of modern x-RAY studies has been the small area of dedicated extragalactic surveys, which has limited our understanding of the high-energy properties of the large source populations detected in wide-area surveys at other wavelengths (for example with galex, 2MASS, spitzer, wise, and herschel). Recent efforts have exploited the full archive of nustar and chandra pointed observations to create source catalogs covering>100 square degrees, producing valuable data sets that have been widely used with other ground- and space-based observations, with more than 50 publications in a few years. However, the existing nustar serendipitous and chandra source catalogs only account for the brightest sources that are individually detected in x-rays, and thus do not exploit the full power of nustar and chandra observations. Nustar and chandra have the unique ability to probe extraordinarily low effective x-RAY fluxes, beyond the detection limit for individual sources, by employing stacking analyses to determine the average x-RAY properties of faint galaxy and AGN populations (e.g., hickox & markevitch 2007). The proposed adap program will develop and utilize tools to perform x-RAY stacking analyses of the entire nustar and chandra archives, for any set of sources detected in wide-area surveys from the UV to the far-IR. We will focus on NASA-affiliated missions, particularly galex, 2MASS, spitzer, wise, and herschel, and will dramatically extend our knowledge of the x-RAY properties of these source populations. Our team has developed stackfast, a software package that enables fast and efficient x-RAY stacking analyses for chandra surveys and has been used successfully in several papers (hickox ET AL. 2007, 2009; chen ET AL. 2013, 2017; goulding ET AL. 2017; cowley ET AL. 2018) . Stackfast works in two steps: (1) extracting photons and exposure information from the nustar and chandra data sets for every object in a master source catalog, and (2) allowing the user to coadd the emission from any subset within the master catalog. Of these, only step (1) is computationally intensive while step (2) can be performed very quickly and easily. Thus we can produce stacked x-RAY databases for entire UV or IR catalogs, which can then be downloaded and coadded by an end user depending on the particular application. There is thus enormous potential to produce a nustar and chandra x-RAY stacking data set that can be used easily and efficiently by the entire astronomical community. The goals of the first phase of this adap will be to (1) adapt stackfast to perform stacking of galex, 2MASS, spitzer, wise, and herschel catalogs, and (2) release stacked x-RAY databases and the corresponding analysis code to the public. In the second phase of this project, we will construct web-based tools to allow the end user to upload their own input catalog, for which photons and exposure information can be extracted from the full archive. These will allow any user to exploit the rich and extensive data sets produced by galex, 2MASS, spitzer, wise, herschel or any future surveys, combined with the power of the full nustar and chandra archives, to obtain extremely sensitive average x-RAY measurements of any population of STARS, galaxies, or AGN. Our work is strongly suited for the adap, as IT is fundamentally multiwavelength in nature and draws on the unique capabilities of multiple NASA surveys to open a new frontier of knowledge. Further, our work is clearly aligned with NASA's strategic objective to "understand the sun, earth, solar system, and universe".