Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/229509

Title

GALEX Arecibo SDSS survey V: the relation between the H I content of galaxies and metal enrichment at their outskirts

Author(s)

Moran, Sean M.;  Heckman, Timothy M.;  Kauffmann, Guinevere;  Dave, Romeel;  Catinella, Barbara;  Brinchmann, Jarle;  Wang, Jing;  Schiminovich, David;  Saintonge, Amelie;  Gracia-Carpio, Javier;  Tacconi, Linda;  Giovanelli, Riccardo;  Haynes, Martha;  Fabello, Silvia;  Hummels, Cameron;  Lemonias, Jenna;  Wu, Ronin

Abstract

We have obtained long-slit spectra of 174 star-forming galaxies with stellar masses greater than 10^10 M_\odot from the GALEX Arecibo SDSS (GASS) survey. These galaxies have both HI and H_2 mass measurements. The average metallicity profile is strikingly flat out to R_90, the radius enclosing 90% of the r-band light. Metallicity profiles which decline steadily with radius are found primarily for galaxies in our sample with low stellar mass (Log(M_*)<10.2), concentration, and/or mean stellar mass density. Beyond ~R_90, however, around 10 percent of the galaxies in our sample exhibit a sharp downturn in metallicity. Remarkably, we find that the magnitude of the outer metallicity drop is well correlated with the total HI content of the galaxy (measured as f_HI=M_HI/M_*). We examine the radial profiles of stellar population ages and star formation rate densities, and conclude that the galaxies with largest outer metallicity drops are actively growing their stellar disks, with mass doubling times across the whole disk only one third as long as a typical GASS galaxy. We also describe a correlation between local stellar mass density and metallicity, which is valid across all galaxies in our sample. We argue that much of the recent stellar mass growth at the edges of these galaxies can be linked to the accretion or radial transport of relatively pristine gas from beyond the galaxies' stellar disks.

Publication type

Journal article

Source

Astrophysical Journal, Vol. 745, no. 1 (Jan 2012), article no. 66

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences;  0305 Organic Chemistry;  0306 Physical Chemistry (Incl. Structural)

Keyword(s)

Galaxies;  Galaxy evolution;  GALEX Arecibo SDSS Survey;  GASS;  ISM;  Star formation;  Stellar content

Publisher

Institute of Physics Publishing

ISSN

0004-637X

Publisher URL

http://dx.doi.org/10.1088/0004-637x/745/1/66

Copyright

Copyright © 2012 The American Astronomical Society. All rights reserved. The American Astronomical Society does not allow Swinburne Research Bank to archive either the accepted manuscript or the published version of the article. However you can find an earlier version of the full text here: http://arxiv.org/abs/1112.1084

Peer reviewed