Fig. 1: Photometry and discovery spectroscopy of J1007_AGN at z ≈ 7.3.
From: A little red dot at z = 7.3 within a large galaxy overdensity
Top: image cut-outs (2 arcsec × 2 arcsec) covering the six filters from ground-based LBT/LBC r- and i-band images and JWST/NIRCam F090W, F115W, F277W and F444W. By design, the source is not detected in the bluest three bands and appears as a red object (F115W − F444W = 1.94 mag) with compact morphology in F115W, F277W and F444W. Referenced apparent magnitudes are calculated from aperture photometry at the source location. Middle: the co-added 2D NIRSpec/MSA spectrum of the three AB-subtracted dither positions as a function of observed wavelength. The 2D spectrum is displayed in pixel coordinates, resulting in a nonlinear observed wavelength axis. The bright trace is the positive co-added spectrum, whereas the dark traces show the four negative traces of the individual AB dithers. Bottom: the one-dimensional optimally extracted co-added spectrum as a function of rest-frame wavelength. Positions of spectral features, including typical line emission observed in AGNs, are indicated with blue dotted lines. Orange data points show the fluxes measured from the NIRCam photometry. Error bars on the photometry denote the 3σ flux error and the wavelength range of the filter in which the transmission is above 50% of its peak value. The blue data points show the synthetic photometry calculated from the MSA spectrum. 2D, two-dimensional.
