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11-20-12, 10:55 PM
In our last test run (galaxies given the 'e' suffix), we analyzed galaxies in a small section of the sky already having the equivalent of 3-year PS1 coverage. One of the goals was to explore the information content of the pixel spectral energy distributions (pixel-SEDs) containing exclusively PS1 data and at ~1 arcsec resolution. Your volunteer computers processed several hundred small [~1 arcmin diameter] galaxies using only PS1 "grizy" pixel-SEDs (not yet including GALEX and WISE). The "grizy" filter set spans wavelengths from 480 nm (g-band) to 1 micron (y-band). The first figure shows PS1 z,r,g color composites (left), stellar mass surface density (total mass of all stars existing per unit area, center) and star formation rate surface density (stellar mass formed per year per unit area averaged over the past 100 Myr, right), for six example galaxies. The results are quite encouraging, and will be improved even further with true panchromatic spectral coverage from GALEX UV to WISE IR. As expected, features tracing recent star formation (such as spiral arms) are much less obvious in the stellar mass maps. Galactic bars are (linear structures centered on the nucleus, such as in the second galaxy on the left) are quite nicely defined in the stellar mass images when present. In true production runs foreground stars will be masked. The lower-left galaxy intentionally shows some pixels not yet returned by volunteers at the time the figure was created, to illustrate the chunks processed by each person. http://dolomiti.pha.jhu.edu/dthilker/POGSgalaxies_PS1only.jpg The second and third figures show the majority of galaxies processed in test run 'e', displaying the stellar mass (color) and SFR surface density (greyscale) respectively. In total there were nearly 0.5 million pixels processed. This would have taken about 10 years locally on a single typical core, but was finished in only a few days thanks to your help! http://dolomiti.pha.jhu.edu/dthilker/NSF2012_PS1SAS_Mstars_coloronblack.jpg http://dolomiti.pha.jhu.edu/dthilker/NSF2012_PS1SAS_invertedgrey.jpg A research paper is currently being written about these results, for submission to one of the professional astronomy journals. Thanks again! More data coming soon...
More... (http://ec2-23-23-126-96.compute-1.amazonaws.com/pogs/forum_thread.php?id=141)
More... (http://ec2-23-23-126-96.compute-1.amazonaws.com/pogs/forum_thread.php?id=141)