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On the origin of Sérsic profiles of galaxies and Einasto profiles of dark-matter halos

Published online by Cambridge University Press:  21 March 2017

Carlo Nipoti
Carlo Nipoti*
Affiliation:
Department of Physics and Astronomy, Bologna University, viale Berti-Pichat 6/2, I-40127 Bologna, Italy email: carlo.nipoti@unibo.it
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Abstract

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The surface-brightness profiles of galaxies I(R) and the density profiles of dark-matter halos ρ(r) are well represented by the same analytic function, named after either Sérsic, I∝e−(R/R*)1/m, or Einasto, ρ∝e−(r/r*)α, where R* and r* are characteristic radii. Systems with high Sérsic index m (or low Einasto index α) have steep central profiles and shallow outer profiles, while systems with low m (or high α) have shallow central profiles and steep profiles in the outskirts. We present the results of idealized numerical experiments which suggest that the origin of these profiles can be traced back to the initial density fluctuation field: high-α (low-m) systems form in smooth regions via few mergers, while low-α (high-m) systems form in clumpy regions via several mergers.

Keywords

dark mattergalaxies: bulgesgalaxies: elliptical and lenticular, cDgalaxies: formationgalaxies: fundamental parametersgalaxies: structure
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S321: Formation and Evolution of Galaxy Outskirts , March 2016 , pp. 87 - 89
Copyright
Copyright © International Astronomical Union 2017 

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