Metallicity Gradient of a Lensed Face-on Spiral Galaxy at Redshift 1.49

• Published in: Astrophysical journal. Letters Vol. 732; no. 1; pp. L14 - jQuery1323917805239='48'
• Main Authors: Yuan, T.-T, Kewley, L. J, Swinbank, A. M, Richard, J, Livermore, R. C
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 01.05.2011; Bristol : IOP Publishing
• Subjects: ABUNDANCE; Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Cosmology and Extra-Galactic Astrophysics; EMISSION; EVOLUTION; GALAXIES; GALAXY CLUSTERS; MOTION; Physics; RED SHIFT; ROTATION; Sciences of the Universe; galaxies: abundances; galaxies: evolution; galaxies: high-redshift; gravitational lensing: strong
• ISSN: 2041-8205; 2041-8213
• DOI: 10.1088/2041-8205/732/1/L14

We present the first metallicity gradient measurement for a grand-design face-on spiral galaxy at z ~ 1.5. This galaxy has been magnified by a factor of 22X by a massive, X-ray luminous galaxy cluster MACS J1149.5+2223 at z = 0.544. Using the Laser Guide Star Adaptive Optics aided integral field spectrograph OSIRIS on KECK II, we target the H Delta *a emission and achieve a spatial resolution of 01, corresponding to a source-plane resolution of 170 pc. The galaxy has well-developed spiral arms and the nebular emission line dynamics clearly indicate a rotationally supported disk with V rot/ Delta *s ~ 4. The best-fit disk velocity field model yields a maximum rotation of V rotsin i = 150 ? 15 km s--1, and a dynamical mass of M dyn = (1.3 ? 0.2) X 1010 cosec2(i) M (within 2.5 kpc), where the inclination angle i = 45? ? 10?. Based on the [N II] and H Delta *a ratios, we measured the radial chemical abundance gradient from the inner hundreds of parsecs out to ~5 kpc. The slope of the gradient is --0.16 ? 0.02 dex kpc--1, significantly steeper than the gradient of late-type or early-type galaxies in the local universe. If representative of disk galaxies at z ~ 1.5, our results support an 'inside-out' disk formation scenario in which early infall/collapse in the galaxy center builds a chemically enriched nucleus, followed by slow enrichment of the disk over the next 9 Gyr.