Department of Astronomy & Physics

Improving mass estimates of galaxies

The masses of galaxies as determined from model fits to resolved images (used here as plotting points) compared to fits using unresolved (i.e., single pixel) images depends on the rate of star formation in the galaxy.

Ph.D. graduate student Sorba and Dr. Sawicki's recent research paper (published in the Monthly Notices of the Royal Astronomical Society) shows that model fits to resolved images of galaxies produce similar mass estimates to model fits to unresloved images for galaxies but only for galaxies that have lower rates of internal star fromation. As the star formation rates increase, the masses derived from unresolved model fits are lower (presumably underestimated) compared to the model fits to the resolved images. Indeed, as they show in the figure above the trend is linear. Astronomers can can continue to estimate the masses of galaxies using unresolved images (necessary for faint galaxies such as high red shift galaxies) and then apply a simple correction to improve the mass estimate.
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