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Galaxy Decomposition Service

Yogesh Wadadekar (STScI)

Milan Bogosavljević (Caltech)

Ashish Mahabal (Caltech)

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Science drivers

How do Hubble types evolve with redshift?

At what redshift does the Hubble sequence form?

Does galaxy formation occur heirarchically or through primodial collapse?

How does the morphology in clusters change as a function of cluster mass and distance from cluster center?

TOOL :

Galaxy photometric decomposition code (FITGAL) performs a chi^2 minimization between a user provided galaxy image and a multicomponent (bulge,disk,point etc.) model.

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Why another web service?

Obtaining the global minimum of a complicated multidimensional chi^2 surface is something of a black art

Many users can test the code on different data in minutes (no compiling! :) )

Building a new Web service (small step for mankind, big for ...) :

We converted a stand alone program into a Web tool.

Simplest approach : - Input HTML form- CGI program to transfer user files to STScI and launch child process- User can visually monitor progress in browser, or run from command line.

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The Web service interface

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Submitting job to STScI...

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Monitoring the iterations....

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All done

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A little bit about the code

(Wadadekar et al, AJ, 1999)

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• Bigger goals for the future

– Integrating the web service to query other imaging services for galaxies to your liking you dont need to have any data locally.

– combine this service with GRID resources so that users can process large samples. We will ourselves attempt to run this code on millions of Sloan survey galaxies using the Teragrid.

– Our extracted parameters can be added as extra columns to the Sloan catalog and made accessible to

the community through Openskyquery.