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Paper: Gas Dynamics in the Non-barred Seyfert Galaxy NGC 4501
Volume: 320, The Neutral ISM in Starburst Galaxies
Page: 271
Authors: Onodera, S.; Koda, J.; Sofue, Y.; Kohno, K.
Abstract: We report high resolution interferometer observations of the central 5 kpc region of NGC 4501. The observations were carried out with the CO line using the Nobeyama Millimeter Array (NMA). It is known that NGC 4501 has high degree of central gas concentration for a non-barred galaxy. The CO major features (1) a nuclear concentration which is resolved into double peaks, (2) spiral arms. The feature (1) has a low star-forming efficiency, which might be due to low Mgas/Mdyn ratio. Double peaks are located on the root of optical spiral arms in a HST image. To understand gas motions in NGC 4501, we did model calculations of gas cloud orbits governed by a stellar spiral potential, which is a modification of the model with a bar potential. The observed CO spirals and non-circular motions were explained with this spiral model. We estimated the loss of angular momentum due to galactic spiral shocks in orbitcrowding regions and gravitational torques exerted by the stellar spirals. We found that the galactic shock is dominant. These mechanisms lead to gas inflow and possibly explain the central-condensed double peaks in NGC 4501.
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