GEOMETRIC CORROBORATION OF THE EARLIEST LENSED GALAXY AT z ≃ 10.8 FROM ROBUST FREE-FORM MODELLING

Abstract

A multiply lensed galaxy, MACS0647-JD, with a probable photometric redshift of -+  z 10.7 0.4 0.6 is claimed to constitute one of the very earliest known galaxies, formed well before reionization was completed. However, spectral evidence that MACS0647-JD lies at high redshift has proven infeasible and so here we seek an independent-lensing-based "geometric redshift" derived from the angles between the three lensed images of MACS0647-JD, using our free-form mass model (WSLAP+) for the lensing cluster MACSJ0647.7+7015 (at z = 0.591). Our lens model uses the nine sets of multiple images, including those of MACS0647-JD, identified by the CLASH survey toward this cluster. We convincingly exclude the low-redshift regime of z<3, for which convoluted critical curves are generated by our method, as the solution bends to accommodate the wide angles of MACS0647-JD for this low redshift. Instead, a best fit to all sets of lensed galaxy positions and redshifts provides a geometric redshift of -+  z 10.8 0.4 0.3 for MACS0647-JD, strongly supporting the higher photometric redshift solution. Importantly, we find a tight linear relation between the relative brightnesses of all nine sets of multiply lensed images and their relative magnifications as predicted by our model. This agreement provides a benchmark for the quality of the lens model, and establishes the robustness of our free-form lensing method for measuring model-independent geometric source distances and for deriving objective central cluster mass distributions. After correcting for its magnification the luminosity of MACS0647-JD remains relatively high at M UV = −19.4, which is within a factor of a few in flux of some surprisingly luminous z;10-11 candidates discovered recently in Hubble blank field surveys.

Spatially Resolved Stellar Populations of 0.3 < z < 6.0 Galaxies in WHL 0137–08 and MACS 0647+70 Clusters as Revealed by JWST: How Do Galaxies Grow and Quench over Cosmic Time?

“…With the addition of HST imaging data from CLASH, new lens models were established using various methods, including Lenstool, LTM, WSLAP, and LensPerfect (Coe et al 2008). These lens models have been used in previous studies in CLASH (e.g., Coe et al 2013;Zitrin et al 2015;Chan et al 2017). Now with the addition of JWST NIRCam imaging data, which add on many new strongly lensed multiple-image candidates (thanks to its high spatial resolution and depth), a This new method has also been implemented in several clusters We used this lens model constructed by Meena et al (2023) for galaxies in the MACS 0647+70 field.…”

Two Lensed Star Candidates at z ≃ 4.8 behind the Galaxy Cluster MACS J0647.7+7015

“…The substantial magnification provided by galaxy cluster lenses has also continuously led to the detection of background high-redshift galaxy candidates in observations with the HST (e.g., Coe et al 2013;Chan et al 2017;Salmon et al 2018;Bhatawdekar et al 2019) and JWST (e.g., Adams et al 2022;Atek et al 2022;Castellano et al 2022;Furtak et al 2022;Hsiao & Coe 2022;Vanzella et al 2022;Williams et al 2022;Yan et al 2022). One of these candidates is MACS0647-JD (Coe et al 2013), a record-breaking, triply imaged galaxy at z ; 10.7, which was first detected in HST imaging of the MACS J0647.7+7015 (hereafter MACS0647; z = 0.591, Ebeling et al 2007) galaxy cluster under the Cluster Lensing and Supernova survey with Hubble (CLASH) 36 program (Postman et al 2012).…”

A free-form lensing model of A370 revealing stellar mass dominated BCGs, in Hubble Frontier Fields images

“…The Hubble Frontier Fields program 1 (or HFF hereafter, Lotz et al 2016) provides the most remarkably detailed examples of gravitational lensing by galaxy clusters, registering hundreds of multiply-lensed galaxies for charting galaxy jdiego@ifca.unican.es 1 http://www.stsci.edu/hst/campaigns/frontier-fields/ formation to unprecedented depths (see e.g Lam et al 2014;Diego et al 2015aDiego et al ,b, 2016. Furthermore, most of these HFF clusters are in a state of collision, enhancing their value for assessing the collisionality of dark matter, a basic assumption of the standard particle interpretation of dark matter (Markevitch et al 2002(Markevitch et al , 2004Springel & Farrar 2007;Randall et al 2008).…”

“…The free-form nature of our method means we can objectively determine the relative distances of any set of multiple images with respect to any other, providing geometric estimates of the source distance for comparison with the independently determined photometric redshifts. We have applied this approach increasingly since it was first demonstrated in A1689 (Broadhurst et al 2005) because the accuracy of the free-form lensing is now sufficiently reliable for this purpose given the relatively high surface density of multiply lensed images reached in the HFF and allows us to confidently measure our own geometric redshift estimates (Lam et al 2014) including photometrically ambiguous high redshift galaxies at z 10 ( Zitrin et al 2014;Chan et al 2016).…”