J/ApJ/777/97 SL2S galaxy-scale lens sample. III. (Sonnenfeld+, 2013)
The SL2S galaxy-scale lens sample.
III. Lens models, surface photometry, and stellar masses for the final sample.
Sonnenfeld A., Gavazzi R., Suyu S.H., Treu T., Marshall P.J.
<Astrophys. J., 777, 97 (2013)>
=2013ApJ...777...97S 2013ApJ...777...97S
ADC_Keywords: Gravitational lensing ; Redshifts ; Galaxies, IR ;
Photometry, HST; Photometry, ugriz
Keywords: galaxies: elliptical and lenticular, cD; gravitational lensing: strong
Abstract:
We present Hubble Space Telescope (HST) imaging data and
Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based
images for the final sample of 56 candidate galaxy-scale lenses
uncovered in the CFHT Legacy Survey as part of the Strong Lensing in
the Legacy Survey (SL2S) project. The new images are used to perform
lens modeling, measure surface photometry, and estimate stellar masses
of the deflector early-type galaxies (ETGs). Lens modeling is
performed on the HST images (or CFHT when HST is not available) by
fitting the spatially extended light distribution of the lensed
features assuming a singular isothermal ellipsoid mass profile and by
reconstructing the intrinsic source light distribution on a pixelized
grid. Based on the analysis of systematic uncertainties and comparison
with inference based on different methods, we estimate that our
Einstein radii are accurate to ∼3%. HST imaging provides a much higher
success rate in confirming gravitational lenses and measuring their
Einstein radii than CFHT imaging does. Lens modeling with ground-based
images, however, when successful, yields Einstein radius measurements
that are competitive with space-based images. Information from the
lens models is used together with spectroscopic information from
companion Paper IV (2013ApJ...777...98S 2013ApJ...777...98S) to classify the systems,
resulting in a final sample of 39 confirmed (grade A) lenses and 17
promising candidates (grade B,C).
Description:
The galaxy-scale Strong Lensing Legacy Survey (SL2S) lenses are found
with a procedure described in detail in Paper I (Gavazzi et al.
2012ApJ...761..170G 2012ApJ...761..170G). All the SL2S lens candidates are first imaged by
the CFHT as part of the Canada-France-Hawaii Telescope Legacy Survey
(CFHTLS). The typical FWHM in the g and i bands is 0.7".
The WIRCam mounted on the CFHT was used to obtain NIR follow-up
photometry for some of the SL2S lens galaxies (Programs 11BF01, PI:
Gavazzi, and 07BF15 PI: Soucail) or from existing surveys like WIRDS
(Bielby et al. 2010A&A...523A..66B 2010A&A...523A..66B, 2012A&A...545A..23B 2012A&A...545A..23B) or from the
ongoing MIRACLES Survey that is gathering deep NIR counterparts to a
subset of the CFHTLS in the W1 and W4 fields (S. Arnouts et al., in
preparation).
In addition to ground-based photometry, 33 of the 56 lens systems
presented here have been observed with HST as part of programs 10876,
11289 (PI Kneib), and 11588 (PI Gavazzi) over the course of cycles 15,
16, and 17, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 84 57 Lens light parameters, CFHT photometry
table5.dat 64 34 Lens light parameters, HST photometry
table6.dat 71 61 Lens model parameters
table7.dat 68 56 Stellar mass measurements
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See also:
II/317 : The CFHTLS Survey (T0007 release) (Hudelot+ 2012)
J/A+A/567/A111 : Multi-color detection of gravitational arcs (Maturi+, 2014)
J/ApJ/755/31 : Compilation of 122 strong gravitational lenses (Cao+, 2012)
J/ApJ/749/65 : H-ATLAS search of strongly lensed gal. (Gonzalez-Nuevo+, 2012)
J/ApJ/749/38 : CFHTLS-SL2S-ARCS strong lens candidates (More+, 2012)
J/ApJ/705/1099 : The Sloan Lens ACS (SLACS) Survey. IX. (Auger+, 2009)
J/A+A/501/461 : Photometric masses of early-type lens galaxies (Grillo+, 2009)
J/ApJ/682/964 : Sloan lens ACS survey. V. (Bolton+, 2008)
J/ApJS/176/19 : COSMOS: strong lens systems (Faure+, 2008)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SL2S]
5- 18 A14 --- SL2S Lens name (G1)
19- 20 A2 --- m_SL2S 2d component (G1)
22- 25 F4.2 arcsec Reff [0.2/2.3] Effective radius (1)
27- 30 F4.2 --- q [0.2/1] Axis ratio of elliptical isophote (1)
32- 36 F5.1 deg PA [-87/88] Position angle; East of North (1)
38- 42 F5.2 mag umag [20.3/25.3] The CFHT u-band magnitude (1)
44- 48 F5.2 mag gmag [18.5/23.9] The CFHT g-band magnitude (1)
50- 54 F5.2 mag rmag [17.3/22.4] The CFHT r-band magnitude (1)
56- 60 F5.2 mag imag [16.8/21.2] The CFHT i-band magnitude (1)
62- 66 F5.2 mag zmag [16.5/20.8] The CFHT z-band magnitude (1)
68- 72 F5.2 mag Jmag [15.9/20]? The CFHT/WIRCam J-band magnitude (1)
74- 78 F5.2 mag Hmag [15/19.4]? The CFHT/WIRCam H-band magnitude (1)
80- 84 F5.2 mag Ksmag [15/20]? The CFHT/WIRCam KS-band magnitude (1)
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Note (1): Best fit parameters for de Vaucouleurs models of the surface
brightness profile of the lens galaxies, after careful manual masking
of the lensed images. The typical uncertainties are a few degrees for
the position angle, Δq∼0.03 for the axis ratio, 0.3 for u-band
magnitudes, 0.2 for g and r-band magnitudes, 0.1 for magnitudes in
the remaining bands, 30% on the effective radii.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SL2S]
5- 18 A14 --- SL2S Lens name (G1)
19- 20 A2 --- m_SL2S 2d component (G1)
22- 25 F4.2 arcsec Reff [0.4/2.5] Effective radius (1)
27- 30 F4.2 --- q [0.2/1] Axis ratio of elliptical isophote (1)
32- 36 F5.1 deg PA [-80/85] Position angle;
Measured East of North (1)
38- 42 F5.2 mag F814W [19/19.2]? HST/ACS F814W filter magnitude (1)
44- 48 F5.2 mag F606W [17.6/22.8]? HST/(ACS or WFPC2) F606W filter
magnitude (1)
50- 54 F5.2 mag F600LP [18.5/21]? HST/WFC3 F600LP filter magnitude (1)
56- 60 F5.2 mag F475X [20.6/23.4]? HST/WFC3 F475X filter magnitude (1)
62- 64 A3 --- Set [,a-d] Set of observations (2)
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Note (1): Best fit parameters for de Vaucouleurs models of the surface
brightness profile of the lens galaxies, after careful manual masking
of the lensed images.
Note (2): Summary of HST observations:
-------------------------------------------------
Set Prog Inst Filter Exp. Time
(s)
-------------------------------------------------
(a) 10876 ACS F814W, F606W 800, 400
(b) 11689 WFPC2 F606W 1200
(c) 11588 WFC3 F600LP, F475X 720
(d) 11588 WFC3 F475X 360
-------------------------------------------------
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SL2S]
5- 18 A14 --- SL2S Lens name (G1)
19- 21 A3 --- m_SL2S Components (G1)
23- 26 F4.2 arcsec Reff [0.05/4.4] Einstein radius
28- 31 F4.2 arcsec e_Reff [0.01/0.3] The 68% confidence interval on Reff
33- 36 F4.2 --- q [0.2/1]? Axis ratio of elliptical
isodensity contour
38- 41 F4.2 --- e_q [0.01/0.4]? The 68% confidence interval on q
43- 47 F5.1 deg PA [-84/86]? Position angle; Measured East of North
49- 52 F4.1 deg e_PA ? The 68% confidence interval on PosAng
54- 58 F5.2 mag mag [22.4/31.8]? Source magnitude (1)
60 A1 --- Grade [A-C] Lens grade (A=confirmed: 39 lenses) (2)
62- 69 A8 --- Note Lens morphology note
71 A1 --- HST Lens has HST imaging? Y=Yes, N=No
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Note (1): Of the de-lensed source in the band used for the lensing analysis:
the bluest available band for HST data, or g band for CFHT data. The
typical uncertainty on the source magnitude is ∼0.5.
Note (2): The systems are graded according to their subjective likelihood of
being strong lenses: grade A are definite lenses, B are probable
lenses, C are possible lenses or, more conservatively, systems for
which the additional dataset does not lead to conclusive answers
about their actual strong lensing nature.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SL2S]
5- 18 A14 --- SL2S Lens name (G1)
20- 24 F5.3 --- z [0.2/0.8]? Lens redshift; discussed in
Paper IV (2013ApJ...777...98S 2013ApJ...777...98S)
26- 30 F5.2 [Msun] logMC [10.4/11.9]? Log stellar mass, Chabrier IMF
32- 35 F4.2 [Msun] e_logMC [0.09/0.2]? Error on logMC
37- 41 F5.2 [Msun] logMS [10.6/11.8]? Log stellar mass, Salpeter IMF
43- 46 F4.2 [Msun] e_logMS [0.06/0.2]? Error on logMS
48- 52 F5.2 [Msun] logMC2 [10.6/12.1]? Log stellar mass,
Chabrier IMF with NIR
54- 57 F4.2 [Msun] e_logMC2 [0.09/0.2]? Error on logMC2
59- 63 F5.2 [Msun] logMS2 [10.9/12]? Log stellar mass,
Salpeter IMF with NIR
65- 68 F4.2 [Msun] e_logMS2 [0.06/0.2]? Error on logMS2
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Global notes:
Note (G1): SL2S = Strong Lensing in the Legacy Survey; identification
is based on position (JHHMMSS+DDMMSS).
* Some systems have two lens galaxies of comparable magnitude; "c2"
indicates this second omponent.
* "gEx" (γext) for a very massive lense (external shear;
see section 4.1)
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History:
From electronic version of the journal
References:
Gavazzi et al. Paper I. 2012ApJ...761..170G 2012ApJ...761..170G
Ruff et al. Paper II. 2011ApJ...727...96R 2011ApJ...727...96R
Sonnenfeld et al. Paper IV. 2013ApJ...777...98S 2013ApJ...777...98S
Sonnenfeld et al. Paper V. 2015ApJ...800...94S 2015ApJ...800...94S
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Apr-2015