James Webb Space Telescope Feed Post

The nature of an ultra-faint galaxy in the cosmic Dark Ages seen with JWST

The SED and NIRSpec spectrum of JD1. Top: NIRCam postage stamp images (top panels) for each of the NIRCam bands used in this study, along with their extracted photometry (red points, and HST photometry in orange), and the best-fit SED (bottom panel, blue curve and diamonds) derived with EAzY. A forced low redshift fit is also shown (grey curve and diamonds) and is disfavored. An inset plot highlights the P(z) of the fit across the entire allowed redshift range. Bottom: The 2D (top) and 1D (bottom) NIRSpec prism spectrum of JD1, with the positive and negative 2D traces indicated by white and red lines, respectively (with widths corresponding to the 1D extraction kernel). The optimally-extracted 1D spectrum is shown in purple (line and fill), with associated flux uncertainties (pink fill) and best-fit continuum model in blue. The combined NIRCam and HST photometry are shown as grey points, with associated uncertainties in black. Simulated NIRSpec spectra using the EAzY best-fit SEDs are shown as dotted grey and blue lines (low-z and high-z, respectively), for illustration. The 1D spectrum is normalized to the F150W band. All uncertainties refer to 1s standard deviation