Structural and dynamical properties of Tidal dwarf galaxies in the tails and bridge of the Guitar galaxy Arp 105

Abstract We present a multi-wavelength (far-ultraviolet to infrared) analysis of two tidal dwarf galaxy (TDG) candidates and a tidal bridge in the interacting system Arp 105 at z = 0.029 in the Abell 1185 cluster. Far-ultraviolet observations obtained with the Ultraviolet Imaging Telescope onboard AstroSat reveal strong FUV emission from the tidal galaxies Arp 105N and Arp 105S, indicating recent star formation. In Arp 105N, strong nebular emission lines and large equivalent widths EW(Hα) = 77.6 ± 1.3 Å and EW(Hβ) = 15.8 ± 1.7 Å imply a dominant starburst age of ~6 - 10 Myr under an instantaneous-burst assumption, while the FUV emission suggests star formation sustained over the past ~100 − 200 Myr. The relatively high metallicity, ~2/3, Z⊙ (based on the strong-line method), is consistent with expectations for a tidal dwarf galaxy formed from material inherited from the host galaxy. Together, these results suggest that Arp 105N hosts a composite stellar population, consisting of older stars stripped from the host galaxy and younger stars formed in situ. Spectral energy distribution modeling yields stellar masses of 5.75 × 109, 0.8 × 109, and $6.8\times 10^{9}\, \rm M_\odot$ for Arp 105N, Arp 105S, and the tidal bridge, respectively. Based on the dynamical mass estimate from VLA HI measurements for Arp 105N and based on CFHT Hα kinematics for A105S, they have a dynamical-to-baryonic mass ratio of ~1.95 and ~1.30, respectively, indicating a deficiency of dark matter. Further observations, particularly integral field spectroscopy and high-resolution 21 cm observations, may provide better constraints into the kinematics and improve understanding of TDG formation.