GALEX Studies of Early-type Galaxies: the UV Rising Flux and Residual Star Formation

Conference paper
Part of the Astrophysics and Space Science Proceedings book series (ASSSP)


We report on studies of early-type galaxies using the Galaxy Evolution Explorer (GALEX) satellite. UV radiation in these galaxies can arise either from hot evolved stars, or by ongoing star formation. GALEX observations have shown that earlier suggestions of a correlation between metallicity and UV rising flux in early-type galaxies are not substantiated in larger samples. The UV excess (UVX) may decline with redshift, the increasing importance of low level star formation makes this a very difficult issue to track. It is possible to match GALEX photometry with that from the Sloan Digital Sky Survey, and to construct NUV-optical color-magnitude diagrams. We see clearly a red sequence of quiescent early type galaxies, and a blue sequence of star forming galaxies. Between the two are found AGN in a Green Valley; there is the suggestion that some galaxies in the star forming blue sequence might transform into red sequence galaxies, perhaps by merging or by the quenching of star formation. We consider these possibilities and report on new observations aimed at further studies of the issue.


Star Formation Stellar Population Elliptical Galaxy Galaxy Evolution Main Galaxy Sample 


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  1. Bell, E. F., et al. 2004, ApJ, 608, 752CrossRefADSGoogle Scholar
  2. Boissier, S., et al. 2007, ApJS, 173, 524CrossRefADSGoogle Scholar
  3. Boselli, A., et al. 2005, ApJ, 629, L29CrossRefADSGoogle Scholar
  4. Brinchmann, J., Charlot, S., White, S. D. M., Tremonti, C., Kauffmann, G., Heckman, T., & Brinkmann, J. 2004, MNRAS, 351, 1151CrossRefADSGoogle Scholar
  5. Brown, T. M., Ferguson, H. C., Smith, E., Bowers, C. W., Kimble, R. A., Renzini, A., & Rich, R. M. 2003, ApJ, 584, L69CrossRefADSGoogle Scholar
  6. Burstein, D., Bertola, F., Buson, L. M., Faber, S. M., & Lauer, T. R. 1988, ApJ, 328, 440CrossRefADSGoogle Scholar
  7. Code, A. D. 1969, PASP, 81, 475CrossRefADSGoogle Scholar
  8. Donas, J., et al. 2007, ApJS, 173, 597CrossRefADSGoogle Scholar
  9. Faber, S. M., et al. 2007, ApJ, 665, 265CrossRefADSGoogle Scholar
  10. Gil de Paz, A., et al. 2007, ApJS, 173, 185CrossRefADSGoogle Scholar
  11. Greggio, L., & Renzini, A. 1990, ApJ, 364, 35CrossRefADSGoogle Scholar
  12. Hoopes, C. G., et al. 2007, ApJS, 173, 441CrossRefADSGoogle Scholar
  13. Kauffmann, G., et al. 2003, MNRAS, 341, 54CrossRefADSGoogle Scholar
  14. Kauffmann, G., et al. 2007, ApJS, 173, 357CrossRefADSGoogle Scholar
  15. Lee, Y.-W., et al. 2005, ApJ, 621, L57CrossRefADSGoogle Scholar
  16. Loh, Y. S., et al. 2008, in preparationGoogle Scholar
  17. Martin, D. C., et al. 2005, ApJ, 619, L1CrossRefADSGoogle Scholar
  18. Martin, D. C., et al. 2007a, Nature, 448, 780Google Scholar
  19. Martin, D. C., et al. 2007b, ApJS, 173, 342Google Scholar
  20. Morrissey, P., et al. 2005, ApJ, 619, L7CrossRefADSGoogle Scholar
  21. Morrissey, P., et al. 2007, ApJS, 173, 682CrossRefADSGoogle Scholar
  22. O’Connell, R. W. 1999, ARA&A, 37, 603CrossRefADSGoogle Scholar
  23. Origlia, L., Valenti, E., Rich, R. M., & Ferraro, F. R. 2006, ApJ, 646, 499CrossRefADSGoogle Scholar
  24. Piotto, G., et al. 2007, ApJ, 661, L53CrossRefADSGoogle Scholar
  25. Ree, C. H., et al. 2007, ApJS, 173, 607CrossRefADSGoogle Scholar
  26. Rich, R. M., Minniti, D., & Liebert, J. 1993, ApJ, 406, 489CrossRefADSGoogle Scholar
  27. Rich, R. M., et al. 1997, ApJ, 484, L25CrossRefADSGoogle Scholar
  28. Rich, R. M., et al. 2005, ApJ, 619, L107CrossRefADSGoogle Scholar
  29. Rich, R. M., et al. 2008, in preparation.Google Scholar
  30. Salim, S., et al. 2007, ApJS, 173, 267CrossRefADSGoogle Scholar
  31. Schiminovich, D., et al. 2007, ApJS, 173, 315CrossRefADSGoogle Scholar
  32. Sohn, S. T., O’Connell, R. W., Kundu, A., Landsman, W. B., Burstein, D., Bohlin, R. C., Frogel, J. A., & Rose, J. A. 2006, AJ, 131, 866CrossRefADSGoogle Scholar
  33. Thilker, D. A., et al. 2007, ApJS, 173, 538CrossRefADSGoogle Scholar
  34. Trager, S. C., Worthey, G., Faber, S. M., Burstein, D., & Gonzalez, J. J. 1998, ApJS, 116, 1CrossRefADSGoogle Scholar
  35. Wyder, T. K. 2007, ApJS, 173, 293CrossRefADSGoogle Scholar
  36. Yi, S. K., et al. 2005, ApJ, 619, L111CrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag New York 2009

Authors and Affiliations

  1. 1.Dept. of Physics and AstronomyUCLALos Angeles

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