• DOI:10.1086/427821
• Corpus ID: 15926611

OPTICAL AND NEAR-INFRARED COLOR PROFILES IN NEARBY EARLY-TYPE GALAXIES AND THE IMPLIED AGE AND METALLICITY GRADIENTS

@article{Wu2005OPTICALAN,
  title={OPTICAL AND NEAR-INFRARED COLOR PROFILES IN NEARBY EARLY-TYPE GALAXIES AND THE IMPLIED AGE AND METALLICITY GRADIENTS},
  author={Hong Wu and Zhengyi Shao and H. J. Mo and Xiao-yang Xia and Zu-gan Deng},
  journal={The Astrophysical Journal},
  year={2005},
  volume={622},
  pages={244-259}
}

• Hong Wu, Z. Shao, +2 authors Z. Deng
• Published 12 April 2004
• Physics
• The Astrophysical Journal

We present results of an age and metallicity gradient analysis inferred from both optical and near-infrared surface photometry. The analysis is based on a sample of 36 nearby early-type galaxies, obtained from the Early Data Release of the Sloan Digital Sky Survey and the Two Micron All Sky Survey. Surface brightness profiles were derived in each band and used to study the color gradients of the galaxies. Using simple stellar population models with both optical and near-infrared colors, we may interpret the color gradients in terms of age and metallicity gradients of galaxies. Using g(Z) equivalent to d log Z(met)/d log R and g(A) = d log (age)/d log R to represent the metallicity and age gradients, we found a median value of g(Z) = -0.25 +/- 0.03 for the metallicity gradient, with a dispersion sigma(gZ) = 0.19 +/- 0.02. The corresponding values for the age gradients were g(A) = 0.02 +/- 0.04 and sigma(gA) = 0.25 +/- 0.03. These results are in good agreement with recent observational results, as well as with recent simulations that suggest that both monolithic collapse and major mergers have played important roles in the formation of early-type galaxies. Our results demonstrate the potential of using multi-wave band colors obtained from current and future optical and infrared surveys in constraining the age and metallicity gradients of early-type galaxies.