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Arxiv: CANUCS: An Updated Mass and Magnification Model of Abell 370 with JWST Published: 3/11/2024 8:00:12 PM Updated: 3/11/2024 8:00:12 PM

Paper abstract: We report an updated mass and magnification model of galaxy cluster Abell 370using new NIRCam and NIRISS data from the CAnadian NIRISS Unbiased ClusterSurvey (CANUCS). Using Lenstool and a combination of archival HST and MUSE datawith new JWST data as constraints, we derive an improved gravitational lensingmodel and extract magnifications of background galaxies with uncertainties.Using our best fit model, we perform a search for new multiply imaged systemsvia predicted positions. We report no new multiply imaged systems withidentifiable redshifts, likely due to already very deep HST and Spitzer data,but confirm a z~8 multiply imaged system by measuring its redshift withNIRISS and NIRSpec spectra. We find that the overall shape of the criticalcurve for a source at z = 9.0 is similar to previous models of Abell 370,with small changes. We investigate the z~8 galaxy with two imagesobservable with an apparent magnitude in the F125W band of 26.0\pm0.2 and25.6\pm0.1. After correcting for the magnifications of the images,7.2^{+0.2}_{-1.2} and 8.7^{+0.4}_{-0.4}, we use SED fitting to find anintrinsic stellar mass of log(M^*/M_{\odot}) = 7.35^{+0.04}_{-0.05},intrinsic SFR of 3.5^{+2.2}_{-1.4} M_{\odot}/yr, and M_{UV} of-21.3^{+0.2}_{-0.2}, which is close to the knee of the luminosity function atthat redshift. Our model, and corresponding magnification, shear, andconvergence maps are available on request and will be made publicly availableon MAST in a CANUCS data release (DOI: 10.17909/ph4n-6n76).