J/A+A/567/A111 Multi-color detection of gravitational arcs (Maturi+, 2014)
Multi-color detection of gravitational arcs.
Maturi M., Mizera S., Seidel G.
<Astron. Astrophys. 567, A111 (2014)>
=2014A&A...567A.111M 2014A&A...567A.111M
ADC_Keywords: Positional data ; Colors ; Redshifts ; Gravitational lensing
Keywords: dark matter - galaxies: clusters: general -
methods: observational - gravitational lensing: strong
Abstract:
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, the number of gravitational arcs discovered so far is
small. The urge for more complete, large samples and unbiased methods
of selecting candidates is rising. A number of methods for the
automatic detection of arcs have been proposed in the literature, but
large amounts of spurious detections retrieved by these methods forces
observers to visually inspect thousands of candidates per square
degree in order to clean the samples. This approach is largely
subjective and requires a huge amount of eye-ball checking, 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 colours of
gravitational arcs detected in the 37deg2 of the CARS survey.
Description:
Gravitational arc candidates identified in the CFHTLS-Archive-Research
Survey (CARS, Erben et al., 2009A&A...493.1197E 2009A&A...493.1197E). The objects have
been selected with the arcfinder described in Seidel and Bartelmann
(2007A&A...472..341S 2007A&A...472..341S) and the colour selection criteria introduced by
in the paper.
The arc images are available at
http://www.ita.uni-heidelberg.de/~maturi/Public/arcs/ .
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
arcs.dat 128 90 Gravitational arc candidates in CFHTLS Archive
Research Survey (CARS) (tables 2 & 3 of the paper)
--------------------------------------------------------------------------------
See also:
J/ApJ/749/38 : CFHTLS-SL2S-ARCS strong lens candidates (More+, 2012)
http://www.ita.uni-heidelberg.de/~maturi/Public/arcs/ : Arc images
Byte-by-byte Description of file: arcs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [arc]
4- 5 I02 --- ID [0/90] Identification name (arcNN[abc]) (1)
6 A1 --- n_ID [abc] how the arc was found (1)
8- 13 A6 --- Field Name of the CARS field
15- 16 I2 h RAh Arc right ascension J2000 (hours)
18- 19 I2 min RAm Arc right ascension J2000 (minutes)
21- 24 F4.1 sec RAs Arc right ascension J2000 (seconds)
26 A1 --- DE- Arc declination J2000 (sign)
27- 28 I2 deg DEd Arc declination J2000 (degrees)
30- 31 I2 arcmin DEm Arc declination J2000 (minutes)
33- 34 I2 arcsec DEs Arc declination J2000 (seconds)
36- 39 F4.2 arcsec Len Arc length
41- 45 F5.2 --- L/W [1.4/14] Arc length to width ratio
47- 50 F4.2 arcsec-1 Curve [0/1.1] Arc curvature
52- 55 F4.1 arcsec+2 Area [1/13] Arc area
57- 60 F4.1 mag u*mag Arc u* magnitude
62- 64 F3.1 mag e_u*mag Arc u* magnitude 1-σ error
66- 69 F4.1 mag g'mag Arc g' magnitude
71- 73 F3.1 mag e_g'mag Arc g' magnitude 1-σ error
75- 78 F4.1 mag r'mag Arc r' magnitude
80- 82 F3.1 mag e_r'mag Arc r' magnitude 1-σ error
84- 87 F4.1 mag i'mag arc i' magnitude
89- 91 F3.1 mag e_i'mag Arc i' magnitude 1-σ error
93- 96 F4.2 --- zlens [0.26/0.82] Lens photometric redshift
99-102 F4.2 --- e_zlens Lens redshift 1-σ error (lower value)
104-107 F4.2 --- E_zlens Lens redshift 1-σ error (upper value)
109 I1 --- Rank [1/3] Arc ranking, 3=very likely (2)
111-128 A18 --- Cat Catalog name of previously known arcs (3)
--------------------------------------------------------------------------------
Note (1): The objects are labelled arcNN[abc].
arcNNa = segmented by the arcfinder and colour selected
arcNNb = segmented by the arcfinder but rejected by the geometrical
constraints provided by the arcfinder
arcNNc = identified only by eye
Note (2): Ranking number means:
1 = unlikely: arc structures which seem physically associated to an
astrophysical object, or which are relatively far from a possible lens
2 = unclear: arc structures with a very promising shape but still being of
dubious origin
3 = very likely: a clear arc structure which curvature is displaced in such
a way to enclose a possible lens cause of its origin, i.e. large
ellipticals or significant concentrations of galaxies.
Note (3): Identification number in Cabanac et al. (2007A&A...461..813C 2007A&A...461..813C,
SL2SJHHMMSS+DDMMSS) or More et al. (2012, J/ApJ/749/38, SANNN) if present.
--------------------------------------------------------------------------------
Acknowledgements:
Matteo Maturi, maturi(at)uni-heidelberg.de
Sebastian Mizera, sam228(at)cam.ac.uk
Gregor Seidel, seidel(at)mpia.de
(End) Patricia Vannier [CDS] 16-May-2014