A T-Dwarf candidate from JWST early release NIRCam data

Abstract

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 James Webb Space Telescope (JWST) NIRCam. In addition to the superb sensitivity, we utilised 7 filters from JWST in near-IR 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 K to 1300 K. Searching through the data from Early Release Observations (ERO) and Early Release Science (ERS), we find 1 promising candidate in the CEERS field. The result of SED fitting suggested an early T spectral type with a low effective temperature of Teff ≈1300 K, the surface gravity of log g ≈ 5.25 cms−2, and an eddy diffusion parameter of logKzz ≈ 7 cm2s−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.