Oral Presentation

Dense molecular gas outflow from the merging galaxy NGC 3256

Author(s): Tomonari Michiyama Daisuke Iono

Presenter: Tomonari Michiyama (NAOJ/SOKENDAI)

We report the new ALMA Cycle 3 results of line survey towards a late stage merging galaxy NGC 3256. NGC 3256 hosts two merging nuclei and the starburst and AGN activities are strongly affecting the chemical and physical properties of the ISM. We have detected more than 20 molecules (e.g., c-C3H2, H13CN, H13CO+, SiO, CCH, HCN, HCO+, HNC, CH3OH, CS, HC3N, CH3CCH, C18O, 13CO) at 2” angular resolution, which is high enough to resolve the double nuclei. In this presentation, we focus on CO, HCN and HCO+ to discuss the high velocity components detected only by those bright molecular lines. Such high velocity components are though to be molecular gas outflow from northern and southern nuclei. Including the CO(1-0) and CO(3-2) archived data, the line ratios suggest that (1) The excitation condition become weak towards edge of the outflow in the starburst triggered outflow. (2) In the case of low luminous AGN like southern nucleus in NGC 3256, the outflowing gas is associated with AGN jet, and warm and dense gas can be newly formed due to interaction between jet and ISM interaction. (3) The HCN is enhanced due to shock especially in red-shifted outflow. In addition, we conducted radiative transfer modeling. By using a Bayesian likelihood analysis, we found that the CO column density and filling factor of outflowing gas is smaller than the gas around nuclei.