A T-dwarf candidate from JWST early release NIRCam data

ABSTRACT We present a distant T-type brown dwarf candidate at ≈2.55 kpc discovered in the Cosmic Evolution Early Release Science (CEERS) fields by JWST NIRCam. In addition to the superb sensitivity, we utilized seven filters from JWST in near-infrared and thus is advantageous in finding faint, previously unseen brown dwarfs. From the model spectra in new JWST/NIRCam filter wavelengths, the selection criteria of F115W–F277W < −0.8 and F277W–F444W > 1.1 were chosen to target the spectrum features of brown dwarfs having temperatures from 500 to 1300 K. Searching through the data from Early Release Observations and Early Release Science, we find one promising candidate in the CEERS field. The result of spectral energy distribution (SED) fitting suggested an early T spectral type with a low effective temperature of Teff ≈1300 K, the surface gravity of $\log {g}\approx 5.25\, \text{cm s}^{-2}$, and an eddy diffusion parameter of log K$_{zz}\approx 7\, \text{cm}^2 \,\text{s}^{-1}$, which indicates an age of ≈1.8 Gyr and a mass of ≈0.05 M⊙. In contrast to typically found T dwarf within several hundred parsecs, the estimated distance of the source is ≈2.55 kpc, showing the JWST’s power to extend the search to a much larger distance.