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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 25 The CLASH Cluster Sample
table2.dat 84 81 Detected Arcs and Properties
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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
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Bytes Format Units Label Explanations
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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)
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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.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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
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Note (1): Note as follows:
d = denotes the false positive detection.
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 24-Jan-2018