Volume 622, February 2019
|Number of page(s)||23|
|Section||Catalogs and data|
|Published online||05 February 2019|
Multifrequency filter search for high redshift sources and lensing systems in Herschel-ATLAS⋆
Instituto de Física de Cantabria, CSIC-UC, Av. de Los Castros s/n, 39005 Santander, Spain
2 Departamento de Física Moderna, Universidad de Cantabria, 39005 Santander, Spain
3 Departamento de Física, Universidad de Oviedo, C. Federico García Lorca 18, 33007 Oviedo, Spain
Accepted: 10 December 2018
We present a new catalog of high-redshift candidate Herschel sources. Our sample is obtained after applying a multifrequency filtering method (“matched multifilter”), which is designed to improve the signal-to-noise ratio of faint extragalactic point sources. The method is tested against already-detected sources from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) and used to search for new high-redshift candidates. The multifilter technique also produces an estimation of the photometric redshift of the sources. When compared with a sample of sources with known spectroscopic redshift, the photometric redshift returned from the multifilter is unbiased in the redshift range 0.8 < z < 4.3. Using simulated data we reproduced the same unbiased result in roughly the same redshift range and determined the error (and bias above z ≈ 4) in the photometric redshifts. Based on the multifilter technique, and a selection based on color, flux, and agreement of fit between the observed photometry and assumed SED, we find 370 robust candidates to be relatively bright high-redshift sources. A second sample with 237 objects focuses on the faint end at high-redshift. These 237 sources were previously near the H-ATLAS detection limit but are now confirmed with our technique as high significance detections. Finally, we look for possible lensed Herschel sources by cross-correlating the first sample of 370 objects with two different catalogs of known low-redshift objects, the redMaPPer Galaxy Cluster Catalog and a catalog of galaxies with spectroscopic redshift from the Sloan Digital Sky Survey Data Release 14. Our search renders a number of candidates to be lensed systems from the SDSS cross-correlation but none from the redMaPPeR confirming the more likely galactic nature of the lenses.
Key words: methods: data analysis / techniques: image processing / surveys / submillimeter: galaxies / galaxies: high-redshift / gravitational lensing: strong
H-ATLAS source FITS (Tables A1 and A2) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A106
© ESO 2019
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