|dc.description.abstract||We analyze multiwavelength observations of the luminous infrared galaxy (LIRGs) NGC 6090.
The infrared luminosity of NGC 6090, LIR=3×10^11 11 L⊙, is about 30 times larger than
the Milky Way. Since the star formation is much related to molecular gas, we observed CO
J=1–0 line emission with the Berkeley Illinois Maryland Association (BIMA) array
to study the molecular gas in NGC 6090. We also analyze UKIRT H_2 ν=1-0 S(1) line emission
to find the distribution of warm molecular gas. For further analyses of the starburst regions,
we present VLA 1.49 GHz (20 cm) continuum and high resolution HST 1.1-μm image as well.
The cold molecular mass traced by CO is 3.2×10^11 M⊙, which is very close to the value
estimated by the single-dish observation (FCRAO, Young et al. 1995). It means that the molecular gas
in NGC 6090 is highly concentrated in the central region of the interacting system. Besides,
the molecular mass is ~ 2.9 times larger than the dynamical mass. Such a unphysical result
might be due to a combination of two effects, inclination and conversion factor. The surface
filling factor is still ~ 4.5 times larger than that of the Milky Way after corrected by
inclination and conversion factor.
Although the 20 cm radio continuum does not have fine correlation with high-density molecular gas,
we suggest the molecular gas might trigger the starburst in NGC 6090. During merging process,
the molecular gas is concentrated into the center of the two galaxies, trigger the starburst, and
then fall into the center of the interacting system. In proof of this suggestion, we argue the
time scale of the falling and the starburst age of NGC 6090.
The warm molecular mass traced by H2 is ~ 1070 M⊙. In addition to the starburst regions
of the east galaxy near the center of interacting system, the warm molecular gas is distributed
over almost the same regions with cold molecular gas. In NGC 6090 most molecular gas exist in the
form of cold H2 gas as compared with warm gas. We also discuss the different excitation mechanisms
of H2 in the central region and the east galaxy, respectively.||en_US|