Multiwavelength morphology and dust emission in low-redshift dwarf galaxies in COSMOS-Web with HST and JWST

Low-mass or dwarf galaxies ((Formula presented) M(Formula presented)) are abundant in the Universe, yet their formation and evolution remain poorly understood. Their enhanced sensitivity to feedback from star formation and active galactic nuclei (AGNs) make them excellent laboratories to test whether feedback prescriptions in cosmological simulations accurately reproduce their interstellar medium (ISM) properties. We present James Webb Space Telescope/near-infrared camera (JWST/NIRCam) and mid-infrared instrument (MIRI) imaging of nine dwarf galaxies from COSMOS-Web survey at redshift (Formula presented), with star formation rates ranging from 0.003 to 0.3 M(Formula presented) yr(Formula presented) and stellar masses of log (Formula presented) M(Formula presented). The detection rate with both NIRCam and MIRI is 100 per cent, indicating that these dwarfs possess substantial ISM content. The detected sample includes a roughly equal mix of early-type and late-type dwarfs, suggesting that it is representative of the broader dwarf galaxy population in low-density environments. We find that the observed MIRI flux distributions are comparable to forward-modelled flux distributions of mass-matched simulated galaxies in TNG50. We further conduct a multiwavelength morphological analysis complementing the JWST NIRCam and MIRI imaging with archival Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) data, employing the CAS (concentration, asymmetry, smoothness) framework. Among the multiwavelength images, MIRI exhibits the largest variation in CAS parameters, likely due to dust lanes and clumps in several galaxies, also suggested by spectral energy distribution (SED) fitting. This suggests that the dust content in these systems may be higher than those implied by rest-frame optical or near-infrared observations alone. Upcoming ultraviolet/optical and mid-infrared spectroscopic follow-up will be critical for constraining the gas kinematics and dust grain properties of dwarf galaxies in low-density environments such as COSMOS.