J/A+A/622/A106 High-redshift candidate Herschel sources (Manjon-Garcia+, 2019)
Multifrequency filter search for high redshift sources and lensing systems in
Herschel-ATLAS.
Manjon-Garcia A., Herranz D., Diego J.M., Bonavera L., Gonzalez-Nuevo J.
<Astron. Astrophys. 622, A106 (2019)>
=2019A&A...622A.106M 2019A&A...622A.106M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Galaxies, IR ; Photometry
Keywords: methods: data analysis - techniques: image processing - surveys -
submillimeter: galaxies - galaxies: high-redshift -
gravitational lensing: strong
Abstract:
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 (SNR) 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 produces
also 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 reproduce 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.
Description:
Photometric and astrometric parameters for 370 candidates to high
redshift sources and 237 candidates to 500 um-risers selected from the
Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) after
applying a matched multifrequency filtering (MMF) method to improve
the signal-to-noise ratio. Candidates to high redshift sources are
characterized mainly by having a signal to noise ratio >5σ in
the three SPIRE channels (250, 350 and 500 microns), among other
selection criteria described in the associated paper. Candidates to
500um-risers are characterized by having a signal-to-noise ratio
≥4σ at 500um and ≤4σ at 250 and 350um, among other
selection criteria described in the associated paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
500riser.dat 222 237 Photometric and astrometric parameters for 237
candidates to 500 um-risers
robustz.dat 222 370 Photometric and astrometric parameters for 370
candidates to high redshift sources
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See also:
J/MNRAS/462/3146 : Herschel-ATLAS DR1 (Valiante+, 2016)
Byte-by-byte Description of file: 500riser.dat robustz.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- HATLAS H-ATLAS IAU Source identification,
HATLAS JHHMMSS.s+DDMMSS (H-ATLAS)
25- 38 A14 --- IDField H-ATLAS Short Source identification
GNN.DRN.NNNNN (ID_Field)
40- 48 F9.5 deg RAdeg Right Ascension (J2000.0) (RAJ2000)
50- 58 F9.5 deg DEdeg Declination (J2000.0) (DEJ2000)
60- 68 F9.5 mJy F250MMF 250um flux estimated from MMF (F250_MMF)
70- 76 F7.5 mJy e_F250MMF 250um 1 sigma flux error estimated from MMF
(E250_MMF)
78- 86 F9.5 mJy F350MMF 350um flux estimated from MMF (F350_MMF)
88- 94 F7.5 mJy e_F350MMF 350um 1 sigma flux error estimated from MMF
(E350_MMF)
96-104 F9.5 mJy F500MMF 500um flux estimated from MMF (F500_MMF)
106-112 F7.5 mJy e_F500MMF 500um 1 sigma flux error estimated from MMF
(E500_MMF)
114-121 F8.5 --- SNRMMF Signal to noise ratio at 250um estimated
from MMF (SNR_MMF)
123-129 F7.5 --- zphMMF Photometric redshift estimated from MMF
(zphotoMMF)
131-137 F7.5 --- e_zphMMF Photometric redshift error estimated from
simulations with MMF (ezphotoMMF)
139-145 F7.3 mJy F250SPIRE 250um flux from H-ATLAS catalog
(F250_SPIRE)
147-152 F6.3 mJy e_F250SPIRE 250um 1 sigma flux error from H-ATLAS
catalog (E250_SPIRE)
154-161 F8.5 --- SNR250SPIRE Signal to noise ratio at 250um
(SNR250_SPIRE)
163-169 F7.3 mJy F350SPIRE 350um flux from H-ATLAS catalog
(F350_SPIRE)
171-176 F6.3 mJy e_F350SPIRE 350um 1 sigma flux error from H-ATLAS
catalog (E350_SPIRE)
178-185 F8.5 --- SNR350SPIRE Signal to noise ratio at 350um
(SNR350_SPIRE)
187-193 F7.3 mJy F500SPIRE 500um flux from H-ATLAS catalog
(F500_SPIRE)
195-200 F6.3 mJy e_F500SPIRE 500um 1 sigma flux error from H-ATLAS
catalog (E500_SPIRE)
202-209 F8.5 --- SNR500SPIRE Signal to noise ratio at 500um
(SNR500_SPIRE)
211-219 F9.5 --- zsp ? Spectroscopic redshift from H-ATLAS
catalog (z_spec)
221-222 I2 --- Rel ? Confidence label after performing a
chi-squared analysis considering PACS
fluxes (Reliability) (1)
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Note (1): Confidence label as follows:
-1 = if there is no PACS fluxes available to use
0 = if the chi-squared value improves when taking into account PACS fluxes
1 = if the chi-squared value worse slightly when taking into account PACS
fluxes
2 = if the chi-squared value is much worse
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Acknowledgements:
Alberto Manjon-Garcia, manjon(at)ifca.unican.es
(End) Alberto Manjon-Garcia [IFCA, Spain], Patricia Vannier [CDS] 12-Dec-2018