Improving z7-11 Galaxy Property Estimates with JWST/NIRCam Medium-Band Photometry
Abstract
The past decade has seen impressive progress in the detection of z>7 galaxies with the Hubble Space Telescope, however little is known about their properties. The James Webb Space Telescope will revolutionise the high-z field by providing NIR (i.e., rest-frame optical) data of unprecedented depth and spatial resolution. Measuring galaxy quantities such as resolved stellar ages or gas metallicity gradients traditionally requires spectroscopy, as broad-band imaging filters are generally too coarse to fully isolate diagnostics such as the 4000 A (rest-frame) break, continuum emission from aged stars, and key emission lines (e.g., [OII], [OIII], Hβ). However, in this paper, we show that adding NIRCam images through a strategically chosen medium-band filter to common wide-band filters sets adopted by ERS and GTO programs delivers tighter constraints on these galactic properties. To constrain the choice of filter, we perform a systematic investigation of which combinations of wide-band filters from ERS and GTO programs and single medium-band filters offer the tightest constraints on several galaxy properties at redshifts z7-11. We employ the JAGUAR extragalactic catalogs to construct statistical samples of physically-motivated mock photometry and conduct SED-fitting procedures to evaluate the accuracy of galaxy property (and photo-z) recovery with a simple star-formation history model. We find that adding >4.1 μm medium filters at comparable depth to the broad-band filters can significantly improve photo-zs and yield close to order-of-magnitude improvements in the determination of quantities such as stellar ages, metallicities, SF-related quantities and emission line fluxes at z8. For resolved sources, the proposed approach enables spatially-resolved determination of these quantities that would be prohibitive with slit spectroscopy.