Abstract
We constrain the spatial gradient of star formation history (SFH) within galaxies using the colour gradients in NUV − u (where NUV stands for near-ultraviolet) and u − i for a local spatially resolved galaxy sample. By splitting each galaxy into an inner and an outer part, we find that most galaxies show negative gradients in these two colours. We first rule out dust extinction gradient and metallicity gradient as the dominant source for the colour gradient. Then using stellar population models, we explore variations in SFH to explain the colour gradients. As shown by our earlier work, a two-phase SFH consisting of an early secular evolution (growth) phase and a subsequent rapid evolution (quenching) phase is necessary to explain the observed colour distributions among galaxies. We explore two different inside-out growth models and two different inside-out quenching models by varying parameters of the SFH between inner and outer regions of galaxies. Two of the models can explain the observed range of colour gradients in NUV − u and u − i colours. We further distinguish them using an additional constraint provided by the u − i colour gradient distribution, under the assumption of constant galaxy formation rate and a common SFH followed by most galaxies. We find the best model is an inside-out growth model in which the inner region has a shorter e-folding time-scale in the growth phase than the outer region. More spatially resolved UV observations are needed to improve the significance of the result.
Document Type
Article
Publication Date
8-30-2017
Digital Object Identifier (DOI)
https://doi.org/10.1093/mnras/stx2216
Funding Information
Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, NASA, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is https://www.sdss.org/.
Repository Citation
Lian, Jianhui; Yan, Renbin; Blanton, Michael; and Kong, Xu, "Inside-Out Growth or Inside-Out Quenching? Clues from Colour Gradients of Local Galaxies" (2017). Physics and Astronomy Faculty Publications. 552.
https://uknowledge.uky.edu/physastron_facpub/552
Notes/Citation Information
Published in Monthly Notices of the Royal Astronomical Society, v. 472, issue 4, p. 4679-4688.
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
The copyright holders have granted the permission for posting the article here.