James Webb Space Telescope Feed Post

Arxiv: JWST/NIRSpec spectroscopy of intermediate-mass quiescent galaxies at z \sim 3-4 Published: 10/11/2024 3:02:56 PM Updated: 10/11/2024 3:02:56 PM

Paper abstract: We present the analysis of three intermediate-mass quiescent galaxies (QGs)with stellar masses of ~10^{10}M_{\rm \odot} at redshifts z~ 3 - 4using NIRSpec low-resolution spectroscopy. Utilising the SED fitting codeBAGPIPES, we confirm these target galaxies are consistent with quiescentpopulation, with their specific star formation rates (sSFR) falling below 2-dexthe star-forming main sequence at the same redshifts. Additionally, we identifythese QGs to be less massive than those discovered in previous works,particularly prior to the JWST era. Two of our target galaxies exhibit thepotentially-blended H{\alpha}+[NII] emission line within their spectra withS/N>5. We discuss whether this feature comes from an Active Galactic Nucleus(AGN) or star formation although future high-resolution spectroscopy isrequired to reach a conclusion. One of the target galaxies is covered byJWST/NIRCam imaging of the PRIMER survey. Using the 2D profile fitting codeGalfit, we examine its morphology, revealing a disc-like profile with aS\'{e}rsic index of n=1.1 \pm 0.1. On the size-mass relation, we find apotential distinction between less-massive (\log_{10}{(M_*/M_\odot)}<10.3)and massive (\log_{10}{(M_*/M_\odot)}>10.3) QGs in their evolutionarypathways. The derived quenching timescales for our targets are less than 1 Gyr.This may result from these galaxies being quenched by AGN feedback, supportingthe AGN scenario of the emission line features.