James Webb Space Telescope Feed Post

JWST's PEARLS: 119 multiply imaged galaxies behind MACS0416, lensing properties of caustic crossing galaxies, and the relation between halo mass and number of globular clusters at z=0.4

High-pass filtered image of the Spock arc with critical curves and possible interpretation of multiply imaged sources. The white curve is the critical curve predicted by the full model (systems with rank A+B and adaptive grid with 495 grid points) at z=1.0054. The image shows multiple unresolved features along the Spock arc. Sources marked with the same color circle are assumed to be the same source that is multiply imaged, and the dashed lines mark the positions of the critical curve based on these sources. The white circles mark a lensed galaxy candidate at a slightly different redshift. If the mass of the smooth component is reduced slightly in this portion of the lens plane, the main CC would move towards the NW up to the position of the long dashed line (˜0.''5 away). The critical line around the member galaxy in the south of the image would then close (smaller dashed line), naturally producing the triplet marked with three green circles. The red and blue critical curves are from two alternative models where the grid configuration is changed allowing a slightly different distribution for the smooth mass component. Because we did not use multiple knots in this arc as constraints, the lensing constraints are insufficient to properly reproduce the multiple crossing positions of the CC. Abstract: We present a new lens model for the z=0.396 galaxy cluster MACS J0416.1-2403 based on a previously known set of 77 spectroscopically confirmed, multiply imaged galaxies plus an additional set of 42 candidate multiply imaged galaxies from past HST and new JWST data. The new galaxies lack spectroscopic redshifts but have geometric and/or photometric redshift estimates that are presented here. The new model predicts magnifications and time delays for all multiple images. The full set of constraints totals 343, constituting the largest sample of multiple images lensed by a single cluster to date. Caustic-crossing galaxies lensed by this cluster are especially interesting. Some of these galaxies show transient events, most of which are interpreted as micro-lensing of stars at cosmological distances. These caustic-crossing arcs are expected to show similar events in future, deeper JWST observations. We provide time delay and magnification models for all these arcs. The time delays and the magnifications for different arcs are generally anti-correlated, as expected from N-body simulations. In the major sub-halos of the cluster, the dark-matter mass from our lens model correlates well with the observed number of globular clusters. This confirms earlier results, derived at lower redshifts, which suggest that globular clusters can be used as powerful mass proxies for the halo masses when lensing constraints are scarce or not available.