J/A+A/666/L9 SMACS J0723.3-7327 first JWST observations (Caminha+, 2022)
First JWST observations of a gravitational lens. Mass model of new multiple
images with near-infrared observations of SMACS J0723.3-7327.
Caminha G.B., Suyu S.H., Mercurio A., Brammer G., Bergamini P., Acebron A.,
Vanzella E.
<Astron. Astrophys. 666, L9 (2022)>
=2022A&A...666L...9C 2022A&A...666L...9C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Gravitational lensing
Keywords: galaxies: clusters: individual: SMACS J0723.3-7327 -
gravitational lensing: strong - cosmology: observations - dark matter
Abstract:
We present our lens mass model of SMACS J0723.3-7327, the first strong
gravitational lens observed by the James Webb Space Telescope (JWST).
We use data from the Hubble Space Telescope and Multi Unit
Spectroscopic Explorer (MUSE) to build our "pre-JWST" lens model, and
refine it with newly available JWST near-infrared imaging in our JWST
model. To reproduce the positions of all multiple lensed images with
good accuracy, the adopted mass parameterization consists of one
cluster-scale component, accounting mainly for the dark matter
distribution, the galaxy cluster members and an external shear
component. The pre-JWST model has, as constraints, 19 multiple images
from six background sources, of which four have secure spectroscopic
redshift measurements from this work. The JWST model has more than
twice the number of constraints, 30 additional multiple images from
another eleven lensed sources. Both models can reproduce very well the
multiple image positions with a rms of 0.39" and 0.51", for the
pre-JWST and JWST models, respectively. The total mass estimates
within a radius of 128kpc (roughly the Einstein radius) are
7.9+0.3-0.2*1013M☉ and 8.7+0.2-0.2*1013M☉, for
the pre-JWST and JWST models, respectively. We predict with our mass
models the redshifts of the newly detected JWST sources, which are
crucial information especially for systems without spectroscopic
measurements for further studies and follow-up observations.
Interestingly, one family detected with JWST is found to be at a very
high redshift, z>7.5 (68% confidence level) and with one image having
lensing magnification of |µ|=9.5+0.9-0.8, making it an
interesting case for future studies. The lens models, including
magnification maps and redshifts estimated from the model are made
publicly available, along with the full spectroscopic redshift
catalogue from MUSE.
Description:
We present our strong lens model of SMACS J0723.3-7327, the first
gravitational lens ever observed by JWST, using newly available data
from NIRCam. With the new data, we doubled the number of model
constraints, increasing the number of multiple images from 19
identified with HST and MUSE data, to 49.
Objects:
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RA (2000) DE Designation(s)
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07 23 13.3 -73 27 25 SMACS J0723.3-7327 = NAME SMACS J0723.3-7327
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
muse.dat 62 78 MUSE redshift catalogue (table A1)
list.dat 142 9 List of fits magnification maps
fits/* . 9 Individual fits magnification maps
files/* . 6 Complementary files
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Description of file: files/*
Caminha2022SMACS0723best_fit.par : input best fit file for the lenstool
software (see https://projets.lam.fr/projects/lenstool/wiki)
Caminha2022SMACS0723to_sample.par : input file for the sampling mode of
lenstool
bayes.dat : 10000 random points from the full sampling
mapsDlsoverDs1 : folder containing the kappa and shear maps adopting
Dls/Dos = 1. The maps are computed for 100 random models from the bayes.dat
file. These maps can be used to compute the magnification factors for any
source redshift using the equation:
magnification = 1.0/[(1.0 - dls/ds*kappa)**2 - (dls/ds*shear)**2],
where dls is the angular diameter distance between the lens (z=0.3872) and
the source, and ds is the angular diameter distance between us (z=0) and the
source for a flat Universe with Omega_mass = 0.3. See
https://en.wikipedia.org/wiki/Gravitational_lensing_formalism#Magnification.
members_v02.dat : file containing the list of cluster members, used as input
to the lenstool software.
obsarcsv01.dat : file containing the list of multiple images, used as input
to the lenstool software.
Byte-by-byte Description of file: muse.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Sequential number
4- 15 F12.8 deg RAdeg Right ascension (J2000)
17- 28 F12.8 deg DEdeg Declination (J2000)
30- 35 F6.4 --- z MUSE redshift
37 I1 --- qf [2/9] Quality flag (1)
39 I1 --- mult [1/3] Number of entries of the same object
in this catalogue used to indicate multiply
lensed sources
41- 46 F6.3 --- Ampli Median lensing amplification from our lens
model MCMC
48- 54 F7.3 --- e_Ampli Lower error on Ampli (68% confidence level)
56- 62 F7.3 --- E_Ampli Upper error on Ampli (68% confidence level)
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Note (1): Quality flag as follows:
3 = secure measurement
2 = probable
9 = redshift estimated from a single emission line
4 = star
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 33 I4 Kibyte size Size of FITS file
35- 65 A31 --- FileName Name of FITS file, in subdirectory fits
67-142 A76 --- Title Title of the FITS file
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Acknowledgements:
Gabriel Caminha, gbcaminha(at)gmail.com
(End) Patricia Vannier [CDS] 06-Oct-2022