Astrophys. J., 865, 17-17 (2018/September-3)
Submillimeter Array observations of extended CO (J=2-1) emission in the interacting galaxy NGC 3627.
LAW C.J., ZHANG Q., RICCI L., PETITPAS G., JIMENEZ-DONAIRE M.J., UEDA J., LU X. and DUNHAM M.M.
Abstract (from CDS):
We present moderate (∼5'') and high angular resolution (∼1'') observations of 12CO (J = 2 - 1) emission toward the nearby interacting galaxy NGC 3627 taken with the Submillimeter Array (SMA). These SMA mosaic maps of NGC 3627 reveal a prominent nuclear peak, inter-arm regions, and diffuse, extended emission in the spiral arms. A velocity gradient of ∼400-450 km s–1 is seen across the entire galaxy with velocity dispersions ranging from <=80 km s–1 toward the nuclear region to <=15 km s–1 in the spiral arms. We also detect unresolved 13CO (J = 2 - 1) line emission toward the nuclear region, southern bar end, and in a relatively isolated clump in the southern portion of the galaxy, while no C18O(J = 2 - 1) line emission is detected at a 3σ rms noise level of 42 mJy beam–1 per 20 km s–1 channel. Using RADEX modeling with a large velocity gradient approximation, we derive kinetic temperatures ranging from ∼5 to 10 K (in the spiral arms) to ∼25 K (at the center) and H2 number densities from ∼400 to 1000 cm–3 (in the spiral arms) to ∼12,500 cm–3 (at the center). From this density modeling, we find a total H2 mass of 9.6 x 109 M☉, which is ∼50% higher than previous estimates made using a constant H2-CO conversion factor, but is largely dependent on the assumed vertical distribution of the CO gas. With the exception of the nuclear region, we also identify a tentative correlation between star formation efficiency and kinetic temperature. We derive a galactic rotation curve, finding a peak velocity of ∼207 km s–1 and estimate a total dynamical mass of 4.94 ± 0.70 x 1010 M☉ at a galactocentric radius of ∼6.2 kpc (121'').
© 2018. The American Astronomical Society. All rights reserved.
galaxies: individual: NGC 3627 - galaxies: interactions - galaxies: kinematics and dynamics - ISM: clouds - ISM: structure
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