Imaging the Molecular Outflows of the Prototypical ULIRG NGC 6240 with ALMA

摘要

We present 0".97 $\times$ 0".53 (470 pc $\times$ 250 pc) resolution CO ($J$ =2-1) observations toward the nearby luminous merging galaxy NGC 6240 with theAtacama Large Millimeter/submillimeter Array. We confirmed a strong COconcentration within the central 700 pc, which peaks between the double nuclei,surrounded by extended CO features along the optical dust lanes ($\sim$11 kpc).We found that the CO emission around the central a few kpc has extremely broadvelocity wings with full width at zero intensity $\sim$ 2000 km s$^{-1}$,suggesting a possible signature of molecular outflow(s). In order to extractand visualize the high-velocity components in NGC 6240, we performed a multipleGaussian fit to the CO datacube. The distribution of the broad CO componentsshow four extremely large linewidth regions ($\sim$1000 km s$^{-1}$) located1-2 kpc away from both nuclei. Spatial coincidence of the large linewidthregions with H$\alpha$, near-IR H$_2$, and X-ray suggests that the broad CO(2-1) components are associated with nuclear outflows launched from the doublenuclei.