James Webb Space Telescope Feed Post

Arxiv: JWST's PEARLS: Transients in the MACS J0416.1-2403 Field Published: 7/14/2023 10:05:24 PM Updated: 10/12/2023 12:16:46 AM

Paper abstract: With its unprecedented sensitivity and spatial resolution, the James WebbSpace Telescope (JWST) has opened a new window for time-domain discoveries inthe infrared. Here we report observations in the only field that has receivedfour epochs (spanning 126 days) of JWST NIRCam observations in Cycle 1. Thisfield is towards MACS J0416.1-2403, which is a rich galaxy cluster at redshiftz=0.4 and is one of the Hubble Frontier Fields. We have discovered 14transients from these data. Twelve of these transients happened in threegalaxies (with z=0.94, 1.01, and 2.091) crossing a lensing caustic of thecluster,and these transients are highly magnified by gravitational lensing.These 12 transients are likely of similar nature to those previously reportedbased on the Hubble Space Telescope (HST) data in this field, i.e., individualstars in the highly magnified arcs. However, these twelve could not have beenfound by HST because they are too red and too faint. The other two transientsare associated with background galaxies (z=2.205 and 0.7093) that are onlymoderately magnified, and they are likely supernovae. They indicate ade-magnified supernova surface density, when monitored at a time cadence of afew months to a ~3--4 micron survey limit of AB ~ 28.5 mag, of ~0.5 per sq.arcmin integrated to z ~ 2. This survey depth is beyond the capability of HSTbut can be easily reached by JWST.