Query : 2014A&A...567A.111M

2014A&A...567A.111M - Astronomy and Astrophysics, volume 567A, 111-111 (2014/7-1)

Multi-colour detection of gravitational arcs.


Abstract (from CDS):

Strong gravitational lensing provides fundamental insights into the understanding of the dark matter distribution in massive galaxies, galaxy clusters, and the background cosmology. Despite their importance, few gravitational arcs have been discovered so far. The urge for more complete, large samples and unbiased methods of selecting candidates increases. Several methods for the automatic detection of arcs have been proposed in the literature, but large amounts of spurious detections retrieved by these methods force observers to visually inspect thousands of candidates per square degree to clean the samples. This approach is largely subjective and requires a huge amount of checking by eye, especially considering the actual and upcoming wide-field surveys, which will cover thousands of square degrees. In this paper we study the statistical properties of the colours of gravitational arcs detected in the 37 deg2 of the CFHTLS-Archive-Research Survey (CARS). Most of them lie in a relatively small region of the (g'-r',r'-i') colour-colour diagram. To explain this property, we provide a model that includes the lensing optical depth expected in a ΛCDM cosmology that, in combination with the sources' redshift distribution of a given survey, in our case CARS, peaks for sources at redshift z∼1. By furthermore modelling the colours derived from the spectral energy distribution of the galaxies that dominate the population at that redshift, the model reproduces the observed colours well. By taking advantage of the colour selection suggested by both data and model, we automatically detected 24 objects out of 90 detected by eye checking. Compared with the single-band arcfinder, this multi-band filtering returns a sample complete to 83% and a contamination reduced by a factor of ∼6.5. New gravitational arc candidates are also proposed.

Abstract Copyright:

Journal keyword(s): dark matter - galaxies: clusters: general - methods: observational - gravitational lensing: strong

VizieR on-line data: <Available at CDS (J/A+A/567/A111): arcs.dat>

Nomenclature: Tables 2-3: [MMS2014] arcNN (Nos arc1-arc90).

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 SL2S J021408-053532 gLe 02 14 08.070 -05 35 32.39           ~ 8 0
2 SL2S J021416-050315 gLe 02 14 16.579 -05 03 15.51           ~ 3 0
3 [SMR2006] VLA J021737-05134 rG 02 17 37.14752 -05 13 29.5242         19.12 ~ 38 0
4 SL2S J021932-053135 gLe 02 19 32.029 -05 31 35.46           ~ 2 0
5 SL2S J022345-042402 gLe 02 23 45.401 -04 24 02.16           ~ 2 0
6 SL2S J022532-045100 gLe 02 25 31.990 -04 51 00.22           ~ 2 0
7 SL2S J023011-055023 gLe 02 30 11.647 -05 50 23.64           ~ 2 0
8 NAME COSMOS Field reg 10 00 28.60 +02 12 21.0           ~ 2552 0

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