An Application of Multi-band Forced Photometry to One Square Degree of SERVS: Accurate Photometric Redshifts and Implications for Future Science
- National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
- Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
- ESA/ESTEC SCI-S, Keplerlaan 1, 2201 AZ, Noordwijk (Netherlands)
- Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)
- Department of Physics and Astronomy, University of California-Riverside, 900 University Avenue, Riverside, CA, 92521 (United States)
- Spitzer Science Center, California Institute of Technology, M/S 314-6, Pasadena, CA 91125 (United States)
- European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile)
- Department of Physics and Astronomy, University of the Western Cape, Robert Sobukwe Road, 7535 Bellville, Cape Town (South Africa)
- Department of Physics, Oxford Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
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{sup 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.
- OSTI ID:
- 22661122
- Journal Information:
- Astrophysical Journal, Supplement Series, Vol. 230, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0067-0049
- Country of Publication:
- United States
- Language:
- English
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