Integral field spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC5668: An unusual flattening in metallicity gradient

Abstract

We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r 36″ 4.4kpc 0.36 (D 25/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r 36″ flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of λ = 0.053 and vc = 167km s-1, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r 36″. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC5668. © 2012. The American Astronomical Society. All rights reserved..