We present \sim 2 ^ { \prime \prime } resolution CO ( 3–2 ) , HCO ^ { + } ( 4–3 ) and 880 \micron continuum images of the luminous infrared galaxy NGC 6240 obtained at the Submillimeter Array .
We find that the spatially resolved CO ( 3–2 ) , HCO ^ { + } ( 4–3 ) and the 880 \micron emission peaks between the two nuclear components that are both known to harbor AGNs .
Our Large Velocity Gradient ( LVG ) analysis performed on each velocity channel suggests that the peak of the molecular gas emission traced in our observations is warm ( T = 20 – 100 K ) , dense ( n _ { H _ { 2 } } = 10 ^ { 5.0 - 5.4 } cm ^ { -3 } ) and moderately optically thin ( \tau = 0.2 – 2 ) in the central 1 kpc .
We also find large column densities of \sim 10 ^ { 23 } cm ^ { -2 } .
Such extreme conditions are observed over \sim 300 km s ^ { -1 } centered around the CO derived systemic velocity .
The derived molecular gas mass from the CO ( 3–2 ) emission and a CO-to-H _ { 2 } conversion factor commonly used for ULIRGs is ( 6.9 \pm 1.7 ) \times 10 ^ { 9 } M _ { \odot } , and this is consistent with the mass derived from previous CO ( 2–1 ) observations .
The gas is highly turbulent in the central kpc ( \Delta v _ { FWZI } \sim 1175 km s ^ { -1 } ) .
Furthermore , possible inflow or outflow activity is suggested from the CO ( 3–2 ) velocity distribution .
We tentatively state that 3.5 \times 10 ^ { 8 } M _ { \odot } of isolated CO ( 3–2 ) emission seen west of the northern disk may be associated with outflows from starburst superwinds , but the gas outflow scenario from one of the central AGN is not completely ruled out .
Piecing all of the information together , the central region of NGC 6240 harbors 2 AGNs , \sim 10 ^ { 10 } M _ { \odot } of molecular gas mass , 5 \times 10 ^ { 7 } M _ { \odot } of dust mass , and has possible evidence of inflow and outflow activity .