H I, star formation and tidal dwarf candidate in the Arp 305 system
Abstract
We present results from our Giant Metrewave Radio Telescope (GMRT) H I observations of the Arp 305 system. The system consists of two interacting spiral galaxies NGC 4016 and NGC 4017, a large amount of resultant tidal debris and a prominent tidal dwarf galaxy (TDG) candidate projected within the tidal bridge between the two principal galaxies. Our higher resolution GMRT H I mapping, compared to previous observations, allowed detailed study of smaller scale features. Our H I analysis supports the conclusion in Hancock et al. that the most recent encounter between the pair occurred ∼4 × 108 yr ago. The GMRT observations also show H I features near NGC 4017 that may be remnants of an earlier encounter between the two galaxies. The H I properties of the bridge TDG candidate include M_{H I} ∼ 6.6 × 108 M⊙ and V_{H I} = 3500 ± 7 km s-1, which are in good agreement with the velocities of the parent galaxies. Additionally, the TDG's H I linewidth of 30 km s-1 and modest velocity gradient together with its star formation rate of 0.2 M⊙ yr-1 add to the evidence favouring the bridge candidate being a genuine TDG. The bridge TDG's Spitzer 3.6 and 4.5 μm counterparts with a [3.6]-[4.5] colour ∼ -0.2 mag suggests that stellar debris may have seeded its formation. Future spectroscopic observations could confirm this formation scenario and provide the metallicity, which is a key criterion for the validation of TDG candidates.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2017
- DOI:
- arXiv:
- arXiv:1704.04344
- Bibcode:
- 2017MNRAS.469.3629S
- Keywords:
-
- galaxies: dwarf;
- galaxies: individual: Arp 305;
- galaxies: interactions;
- galaxies: spiral;
- galaxies: star formation;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 14 pages, 9 figures, Accepted in MNRAS