A Test of Galaxy Evolutionary Models via Angular Sizes

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Session 71 -- Galaxy and CBR Distribution
Display presentation, Friday, January 14, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[71.12] A Test of Galaxy Evolutionary Models via Angular Sizes

Im, M., Griffiths, R., Neuschaefer, L., Ratnatunga, K., Casertano, S. (Dept. of Physics \& Astronomy, The Johns Hopkins University)

The angular sizes of galaxies are explored as a potential tool in distinguishing between different galaxy evolutionary models.

The angular size distribution, i.e. the number of galaxies as a function of half light radius, shows that the merging model may be separable from the mild evolution model or the no evolution model. In the merging model, galaxies are intrinsically smaller and fainter in the past than present day galaxies -- the angular size distribution shifts to smaller sizes, while in the other models, the angular size distributions reflect the relatively larger sizes.

We have also explored the predicted angular size distribution as a function of HST selection effects -- the selection effects do change the output, since HST tends to exclude low surface brightness, large sized galaxies. we show that this effect may not be important enough to change the results significantly.

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