Galaxy secular mass flow rate determination using the potential-density phase shift approach: Application to six nearby spiral galaxies |
| |
| Institution: | 1. Department of Physics and Astronomy, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA;2. Department of Physics and Astronomy, University of Alabama, 514 University Blvd E, Box 870324, Tuscaloosa, AL 35487, USA;1. Department of Mathematics, S.G.B. Amravati University, Amravati 444602, India;2. Department of Mathematics, Adarsh Education Society’s, Arts, Commerce & Science College, Hingoli 431513, India;1. Aryabhatta Research Institute of observational sciencES (ARIES), Manora Peak, Nainital 263 002, India;2. Indian Institute of Astrophysics, Koramangala, Bangalore 560 034, India;3. Kokugakuin University, Higashi, Shibuya-ku, Tokyo 150-8440, Japan;4. Kiso Observatory, School of Science, University of Tokyo, Mitake, Kiso-machi, Kiso-gun, Nagano-ken 397-0101, Japan;5. Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France;6. Institute of Astronomy, National Central University, 300 Jhongda Rd, Jhongli, Taoyuan Country 32054, Taiwan;7. Department of Physics, Kumaun University, Nainital 263 002, India;1. Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, China;2. Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, China;3. University of Chinese Academy of Sciences, Beijing 100049, China |
| |
| Abstract: | Using the potential-density phase shift approach developed by the present authors in earlier publications, we estimate the magnitude of radial mass accretion/excretion rates across the disks of six nearby spiral galaxies (NGC 628, NGC 3351, NGC 3627, NGC 4321, NGC 4736, and NGC 5194) having a range of Hubble types. Our goal is to examine these rates in the context of bulge building and secular morphological evolution along the Hubble sequence. Stellar surface density maps of the sample galaxies are derived from SINGS 3.6 μm and SDSS i-band images using colors as an indicator of mass-to-light ratios. Corresponding molecular and atomic gas surface densities are derived from published CO (1-0) and HI interferometric observations of the BIMA SONG, THINGS, and VIVA surveys. The mass flow rate calculations utilize a volume-type torque integral to calculate the angular momentum exchange rate between the basic state disk matter and what we assume to be density wave modes in the observed galaxies. This volume-type integral contains the contributions from both the gravitational surface torque couple and the advective surface torque couple at the nonlinear, quasi-steady state of the wave modes, in sharp contrast to its behavior in the linear regime, where it contains only the contribution from the gravitational surface torque couple used by Lynden-Bell & Kalnajs in 1972. The potential-density phase shift approach yields angular momentum transport rates several times higher than those estimated using the Lynden-Bell and Kalnajs approach. And unlike Lynden-Bell and Kalnajs, whose approach predicts zero mass redistribution across the majority of the disk surface (apart from the isolated locations of wave-particle resonances) for quasi-steady waves, the current approach leads to predictions of significant mass redistribution induced by the quasi-steady density wave modes, enough for the morphological types of disks to evolve substantially within its lifetime. This difference with the earlier conclusions of Lynden-Bell and Kalnajs reflects the dominant role played by collisionless shocks in the secular evolution of galaxies containing extremely non-linear, quasi-steady density wave modes, thus enabling significant morphological transformation along the Hubble sequence during a Hubble time. We show for the first time also, using observational data, that stellar mass accretion/excretion is just as important, and oftentimes much more important, than the corresponding accretion/excretion processes in the gaseous component, with the latter being what had been emphasized in most of the previous secular evolution studies. |
| |
| Keywords: | Galaxies: kinematics and dynamics Galaxies: structure Galaxies: evolution Galaxies: spiral |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
