Quenching Depends on Morphologies: Implications From the Ultraviolet-optical Radial Color Distributions in Green Valley Galaxies
Year: 2014
Type: article
Abstract: In this Letter, we analyze the radial ultraviolet–optical color distributions in a sample of low redshift green valley galaxies, with the Galaxy Evolution Explorer ( GALEX )+Sloan Digital Sky Survey (SDSS) images, to investigate how the residual recent star formation is distributed in these galaxies. We find that the dust-corrected u − r colors of early-type galaxies (ETGs) are flat out to R 90 , while the colors monotonously turn blue when r > 0.5 R 50 for late-type galaxies (LTGs). More than half of the ETGs are blue-cored and have remarkable positive NUV − r color gradients, suggesting that their star formations are centrally concentrated. The rest have flat color distributions out to R 90 . The centrally concentrated star formation activity in a large portion of ETGs is confirmed by the SDSS spectroscopy, showing that ∼50% of the ETGs have EW(Hα) >6.0 Å. Of the LTGs, 95% show uniform radial color profiles, which can be interpreted as a red bulge plus an extended blue disk. The links between the two kinds of ETGs, e.g., those objects having remarkable "blue-cores" and those having flat color gradients, are less known and require future investigations. It is suggested that the LTGs follow a general model by which quenching first occurs in the core regions, and then finally extend to the rest of the galaxy. Our results can be re-examined and have important implications for the IFU surveys, such as MaNGA and SAMI.
Authors: Zhizheng Pan, Jinrong Li, Weipeng Lin, Jing Wang, Xu Kong
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2009635594