Evidence in favor of Density Wave Theory, through multiwavelength image analysis, spatially resolved stellar clusters and star formation history maps
Abstract
Stationary density wave theory, originally proposed by C.C. Lin and Frank Shu (Lin & Shu 1964), explains the nature and the origin of spiral arm structures in galaxies as density waves which propagates through the galactic disk. It predicts the existence of an age gradient across the spiral arm with a change in the age gradient direction at the co-rotation radius. Using an image overlaying technique we were able develop a method for identifying the co-rotation radius. By considering spatially resolved stellar clusters of different ages and by analyzing star formation history maps we have found compelling results in favor of Density Wave Theory. We have derived star-formation history (SFH) maps with LIGHTNING (Eufrasio et al. 2017) spectral energy distribution (SED) fitting procedure, which incorporated photometric data from GALEX, Swift, SDSS, 2MASS, Spitzer, WISE, and Herschel. The SFH were derived non-parametric bins of 0-10Myr, 10-100Myr, 0.1-1Gyr, 1-5Gyr, and 5-13.6Gyr. The dynamic evolution of spiral arms can be traced by observing these stellar cluster maps and SFH maps. They can be quantified by tracing spiral arms, measuring pitch angles and also by observing the azimuthal offsets relative to the dust lanes. 8µm, Infrared Spitzer images were used as a tracer for dust lanes, hence depicting the maximum intensity locations of the density wave.
- Publication:
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American Astronomical Society Meeting Abstracts #234
- Pub Date:
- June 2019
- Bibcode:
- 2019AAS...23412403A