J/A+A/627/A31 Statistical HATLAS Lensed Objects Selec. (Gonzalez-Nuevo+, 2019)
SHALOS: Statistical Herschel-ATLAS lensed objects selection.
Gonzalez-Nuevo J., Suarez Gomez S.L., Bonavera L., Sanchez-Lasheras F.,
Argueso F., Toffolatti L., Herranz D., Gonzalez-Gutierrez C.,
Garcia Riesgo F., de Cos Juez F.J.
<Astron. Astrophys. 627, A31 (2019)>
=2019A&A...627A..31G 2019A&A...627A..31G (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR; Galaxy catalogs; Gravitational lensing
Keywords: gravitational lensing: strong - methods: data analysis -
submillimeter: galaxies
Abstract:
The statistical analysis of large sample of strong lensing events can
be a powerful tool to extract astrophysical or cosmological valuable
information. Their selection using submillimetre galaxies has been
demonstrated to be very effective with more than ∼200 proposed
candidates in the case of Herschel-ATLAS data and several tens in the
case of the South Pole Telescope. However, the number of confirmed
events is still relatively low, i.e. a few tens, mostly because of the
lengthy observational validation process on individual events.
In this work we propose a new methodology with a statistical selection
approach to increase by a factor of ∼5 the number of such events
within the Herschel-ATLAS data set. Although the methodology can be
applied to address several selection problems, it has particular
benefits in the case of the identification of strongly lensed
galaxies: objectivity, minimal initial constrains in the main
parameter space, and preservation of statistical properties.
The proposed methodology is based on the Bhattacharyya distance as a
measure of the similarity between probability distributions of
properties of two different cross-matched galaxies. The particular
implementation for the aim of this work is called SHALOS and it
combines the information of four different properties of the pair of
galaxies: angular separation, luminosity percentile, redshift,
and the ratio of the optical to the submillimetre flux densities.
The SHALOS method provides a ranked list of strongly lensed galaxies.
The number of candidates within ∼340°2 of the
Herschel-ATLAS surveyed area for the final associated probability,
Ptot>0.7, is 447 and they have an estimated mean amplification
factor of 3.12 for a halo with a typical cluster mass. Additional
statistical properties of the SHALOS candidates, as the correlation
function or the source number counts, are in agreement with previous
results indicating the statistical lensing nature of the selected
sample.
Description:
SHALOS catalogues for the H-ATLAS GAMA and NGP fields.
For each entry in one of the H-ATLAS catalogues with a cross-matched
optical galaxy, we estimated the associated Ptot. Then all the
entries with Ptot<0.1 were removed and the remaining were sorted
by their Ptot associated value in decreasing order.
From the official H-ATLAS catalogues, we maintained the most critical
information: name, the Herschel flux densities and r magnitude,
angular separation, LR reliability, and the optical spectroscopic and
photometric redshift. Then we added the SHALOS intermediate
information as submillimetre redshifts, bolometric luminosity, the
four associated probabilities of the observables and the final total
probability.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gn19-g09.dat 236 1374 SHALOS catalogue for the H-ATLAS GAMA09 field
gn19-g12.dat 236 1377 SHALOS catalogue for the H-ATLAS GAMA12 field
gn19-g15.dat 236 1506 SHALOS catalogue for the H-ATLAS GAMA15 field
gn19-ngp.dat 236 4129 SHALOS catalogue for the H-ATLAS NGP field
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See also:
J/MNRAS/415/2336 : Herschel-ATLAS Science Demonstration Catalog (Rigby+, 2011)
J/MNRAS/462/1910 : H-ATLAS NGP LOFAR radio catalogue (Hardcastle+, 2016)
Byte-by-byte Description of file: gn19-*.dat
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Bytes Format Units Label Explanations
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2- 24 A23 --- HATLAS HATLAS IAU name, JHHMMSS.s+DDMMSS
26- 35 F10.6 deg RAdeg Right ascension (J2000.0)
37- 46 F10.6 deg DEdeg Declination (J2000.0)
48- 53 F6.3 Jy F250Best 250um best flux
55- 59 F5.3 Jy e_F250Best 250um 1 sigma best flux error
61- 65 F5.3 Jy F350Best 350um best flux
67- 71 F5.3 Jy e_F350Best 350um 1 sigma best flux error
73- 77 F5.3 Jy F500Best 500um best flux
79- 83 F5.3 Jy e_F500Best 500um 1 sigma best flux error
85- 90 F6.3 Jy F100Best ?=-1 100um best flux
92- 97 F6.3 Jy e_F100Best ?=-1 100um 1 sigma best flux error
99-104 F6.3 Jy F160Best ?=-1 160um best flux
106-111 F6.3 Jy e_F160Best ?=-1 160um 1 sigma best flux error
114-119 F6.4 arcsec Sep SPIRE-optical separation
121-125 F5.3 --- Rel LR Reliability
127 I1 --- GSQ [0/3]? GSQ flag (1)
129-147 I19 --- SDSSobjId SDSS-II (DR7) or SDSS-III (DR9) ID
149-152 F4.2 --- zph Photometric redshift from ANNZ
154-157 F4.2 --- e_zph Error in zph
159-164 F6.2 --- zsp Spectroscopic redshift
166-170 F5.2 --- zsmm Sub-mm photometric redshift
172-176 F5.2 --- e_zsmm Error in sub-mm zph
178-185 E8.2 --- normsmm SED zph normalisation
187-194 E8.2 --- e_normsmm Error in SED normalisation
196-200 F5.2 Lsun Lbol Bolometric luminosity
203-206 F4.2 Lsun e_Lbol Error in bolometric luminosity
208-212 F5.3 --- Pratio Flux ratio probability
214-218 F5.3 --- Ppos Positional probability
220-224 F5.3 --- Pz Redshift probability
226-230 F5.3 --- PLbol Lbol probability
232-236 F5.3 --- Ptot Total probability
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Note (1): GSQ flag as follows:
0 = galaxy
1 = star
2 = quasar
3 = quasar candidate based on colour selection
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Acknowledgements:
Joaquin Gonzalez-Nuevo, gnuevo(at)uniovi.es
(End) J. Gonzalez-Nuevo [UNIOVI, Spain], P. Vannier [CDS] 27-May-2019