Integral Field Spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC5668: an unusual flattening in metallicity gradient

TL;DR

This study uses integral field spectroscopy and multi-wavelength imaging to analyze the metallicity gradient of NGC 5668, revealing an unusual flattening beyond a certain radius and suggesting complex evolutionary processes.

Contribution

It provides the first detailed bi-dimensional metallicity map of NGC 5668 and links observational data with chemo-spectrophotometric models to understand disk evolution.

Findings

Metallicity gradient flattens beyond 36 arcseconds

Model predictions match observed rotation curve and metallicity within inner regions

Outer disk deviations suggest influence of gas transfer and bar dynamics

Abstract

We present the analysis of the full bi-dimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the PPAK IFU at the Calar Alto observatory 3.5m telescope. We make use of broad-band imaging to provide further constraints on the evolutionary history of the galaxy. This dataset 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 NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that, while inwards of r\,$\sim\,36",\sim$\,4.4kpc\,$\sim$\,0.36\,$(\frac {D_{25}}{2})$ the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r$\sim36"$ flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 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 $\lambda$=0.053 and v$_{c}$=167\,km\,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\,$\sim36\arcsec$. The same is true for the colors despite of 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 NGC 5668.