2017/04/30 by Kristina Nyland, Mark Lacy, Anna Sajina +8
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Brightness #Fiducial marker #Galaxies: Formation, Evolution, Phenomena #Galaxy #Outlier #Photometric redshift #Photometry (optics) #Redshift #Sky #Surface brightness #astro-ph.GA #astro-ph.IM
paper · pdf · doi:10.3847/1538-4365/aa6fed
accepted to ApJ, 22 pages, 12 figures
openalex created_date 2017/04/28 · openalex publication_date 2017/05/01 · arxiv created 2017/05/24 · arxiv updated 2017/05/25 · openalex updated_date 2026/08/08
Abstract We apply The Tractor image modeling code to improve upon existing multi-band photometry for the Spitzer Extragalactic Representative Volume Survey (SERVS). SERVS consists of post-cryogenic Spitzer observations at 3.6 and 4.5 μ m over five well-studied deep fields spanning 18 deg 2 . In concert with data from ground-based near-infrared (NIR) and optical surveys, SERVS aims to provide a census of the properties of massive galaxies out to z ≈ 5. To accomplish this, we are using The Tractor to perform “forced photometry.” This technique employs prior measurements of source positions and surface brightness profiles from a high-resolution fiducial band from the VISTA Deep Extragalactic Observations survey to model and fit the fluxes at lower-resolution bands. We discuss our implementation of The Tractor over a square-degree test region within the XMM Large Scale Structure field with deep imaging in 12 NIR/optical bands. Our new multi-band source catalogs offer a number of advantages over traditional position-matched catalogs, including (1) consistent source cross-identification between bands, (2) de-blending of sources that are clearly resolved in the fiducial band but blended in the lower resolution SERVS data, (3) a higher source detection fraction in each band, (4) a larger number of candidate galaxies in the redshift range 5 < z < 6, and (5) a statistically significant improvement in the photometric redshift accuracy as evidenced by the significant decrease in the fraction of outliers compared to spectroscopic redshifts. Thus, forced photometry using The Tractor offers a means of improving the accuracy of multi-band extragalactic surveys designed for galaxy evolution studies. We will extend our application of this technique to the full SERVS footprint in the future.