Mathematics – Logic
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21724616m&link_type=abstract
American Astronomical Society, AAS Meeting #217, #246.16; Bulletin of the American Astronomical Society, Vol. 43, 2011
Mathematics
Logic
Scientific paper
We have analyzed surface brightness maps for disk galaxies formed in recent GASOLINE hydrodynamical cosmological simulations. To better understand stellar mass distributions, we directly compared classic photometric decomposition techniques, based on light profiles, with a kinematic decomposition based on particle positions and velocities. These galaxies exhibit masses, structural parameters, and colors typical of early type spirals, and so are excellent proxies for observed spiral galaxies. Surface brightness profiles were generated to model the light distributions in SDSS, HST ACS, and Spitzer IRAC bands. These images are based on local star formation histories and include a detailed treatment of light reprocessing by dust based on the 3D distribution of stars, gas and metals. Photometric bulge/disk decompositions and estimates of disk scale lengths were performed using the GALFIT modelling tool. Kinematic decompositions were made directly from simulation outputs and use the ratio of each stellar particle's angular momentum to the momentum of the co-rotating circular orbit, as well as particle binding energy, to assign it to either bulge, pseudo-bulge, disk or halo components.
Radial surface brightness profiles are commonly used to understand the underlying mass distribution of galaxies, and to provide insight into their formation and evolution. In the case of disk-dominated galaxies, such surface brightness profiles are typically described by a spheroidal bulge and an exponential disk; however disk galaxies are more dynamically complex systems than might be suggested by simple bulge and disk decompositions. We found that the photometrically identifed bulge often consists of a combination of a kinematically identifed non-rotating, spherical, classic bulge made of old stars plus inner disk stars, and a rotating, flattened pseudo-bulge. This suggests that many photometric decompositions of disk galaxies may overestimate bulge stellar mass, and thus systematically underestimate the importance of the disk component at redshifts z > 0.5.
Brooks Alyson M.
Governato Fabio
McCleary Jacqueline E.
Vogt Nicole P.
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