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J/ApJ/817/85      Properties of giant arcs behind CLASH clusters     (Xu+, 2016)

The detection and statistics of giant arcs behind CLASH clusters. Xu B., Postman M., Meneghetti M., Seitz S., Zitrin A., Merten J., Maoz D., Frye B., Umetsu K., Zheng W., Bradley L., Vega J., Koekemoer A. <Astrophys. J., 817, 85 (2016)> =2016ApJ...817...85X (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Gravitational lensing ; Morphology ; Redshifts ; Photometry, HST Keywords: galaxies: clusters: general - gravitational lensing: strong - methods: numerical - methods: observational - methods: statistical Abstract: We developed an algorithm to find and characterize gravitationally lensed galaxies (arcs) to perform a comparison of the observed and simulated arc abundance. Observations are from the Cluster Lensing And Supernova survey with Hubble (CLASH). Simulated CLASH images are created using the MOKA package and also clusters selected from the high-resolution, hydrodynamical simulations, MUSIC, over the same mass and redshift range as the CLASH sample. The algorithm's arc elongation accuracy, completeness, and false positive rate are determined and used to compute an estimate of the true arc abundance. We derive a lensing efficiency of 4±1 arcs (with length ≥6" and length-to-width ratio ≥7) per cluster for the X-ray-selected CLASH sample, 4±1 arcs per cluster for the MOKA-simulated sample, and 3±1 arcs per cluster for the MUSIC-simulated sample. The observed and simulated arc statistics are in full agreement. We measure the photometric redshifts of all detected arcs and find a median redshift zs=1.9 with 33% of the detected arcs having zs>3. We find that the arc abundance does not depend strongly on the source redshift distribution but is sensitive to the mass distribution of the dark matter halos (e.g., the c-M relation). Our results show that consistency between the observed and simulated distributions of lensed arc sizes and axial ratios can be achieved by using cluster-lensing simulations that are carefully matched to the selection criteria used in the observations. Description: Giant arcs are found in the CLASH images and in simulated images that mimic the CLASH data, using an efficient automated arc-finding algorithm whose selection function has been carefully quantified. CLASH is a 524-orbit multicycle treasury program that targeted 25 massive clusters with 0.18<z<0.90. Twenty of the CLASH clusters are selected based on their X-ray characteristics. The CLASH observations for each cluster consist of 16 broadband images (spanning the range 0.23µ-1.6µ) using the WFC3/UVIS, WFC3/IR, and ACS/WFC instruments on board HST. We run our arc finder on the detection (ACS + WFC3/IR) image created for each cluster. We detect a raw total of 187 arcs with l/w≥6.5 in 20 X-ray-selected CLASH clusters. After applying our minimum arc length criterion l≥6", the arc count drops to 81 giant arcs selected from the 20 X-ray-selected CLASH clusters. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 77 25 The CLASH Cluster Sample table2.dat 84 81 Detected Arcs and Properties
See also: J/MNRAS/406/1318 : Lensed-arc statistics of galaxy clusters (Horesh+, 2010) J/A+A/562/A86 : CLASH. Photometric + photo-z catalog (Jouvel+, 2014) J/ApJ/801/44 : HST lensing analysis of the CLASH sample (Zitrin+, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 A6 --- Sample Cluster sample identifier (1) 8- 23 A16 --- Cluster Cluster name 25- 35 A11 --- Other Other cluster name 37- 38 I2 h RAh Hour of Right Ascension (J2000) 40- 41 I2 min RAm Minute of Right Ascension (J2000) 43- 47 F5.2 s RAs Second of Right Ascension (J2000) 48 A1 --- n_RAs [a] Note on RAs (2) 50 A1 --- DE- Sign of the Declination (J2000) 51- 52 I2 deg DEd Degree of Declination (J2000) 54- 55 I2 arcmin DEm Arcminute of Declination (J2000) 57- 60 F4.1 arcsec DEs Arcsecond of Declination (J2000) 61 A1 --- n_DEs [a] Note on DEs (2) 63- 67 F5.3 --- z Redshift of cluster 69- 72 F4.2 10+15Msun M200c ? Cluster mass M200c (in 1015M/h) 74- 77 F4.2 10+15Msun e_M200c ? Uncertainty in M200c (in 1015M/h)
Note (1): Sample as follows: X-ray = X-Ray-selected cluster; High-m = High-magnification cluster. Note (2): Note as follows: a = Central cluster coordinates derived from optical image.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 16 A16 --- Cluster Cluster name 18- 19 I2 --- Arc [1/14] Arc identifier 20 A1 --- n_Arc [d] Note on Arc (1) 22- 27 F6.2 deg RAdeg Right Ascension in decimal degrees (J2000) 29- 34 F6.2 deg DEdeg Declination in decimal degrees (J2000) 36- 42 F7.2 pix Xpos X coordinate in pixels 44- 50 F7.2 pix Ypos Y coordinate in pixels 52- 56 F5.2 arcsec l Arc length 58- 62 F5.2 --- l/w Arc length to width ratio 64- 68 F5.2 arcsec RD Radial distance from the arc center to the cluster center 70- 73 F4.2 --- RD/r200 Normalized radial distance by r200 75- 78 F4.2 --- zphot Photometric redshift 80- 84 F5.2 mag F814W AB magnitude in the F814W band from CANDELS
Note (1): Note as follows: d = denotes the false positive detection.
History: From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 24-Jan-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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