Inverted metallicity gradients in two Virgo cluster star-forming dwarf galaxies: evidence of recent merging?

DOI: 
10.1093/mnras/staa2382
Publication date: 
01/08/2020
Main author: 
Grossi, M.
IAA authors: 
García-Benito, R.
Authors: 
Grossi, M.;García-Benito, R.;Cortesi, A.;Gonçalves, D. R.;Gonçalves, T. S.;Lopes, P. A. A.;Menéndez-Delmestre, K.;Telles, E.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Volume: 
498
Pages: 
1939-1950
Abstract: 
We present integral field spectroscopy observations of two star-forming dwarf galaxies in the Virgo cluster (VCC 135 and VCC 324) obtained with Potsdam Multi-Aperture Spectrograph/PPak at the Calar Alto 3.5 m telescope. We derive metallicity maps using the N2 empirical calibrator. The galaxies show positive gas metallicity gradients, contrarily to what is usually found in other dwarfs or spiral galaxies. We measure gradient slopes of 0.20 ± 0.06 and 0.15 ± 0.03 dex/R<SUB>e</SUB> for VCC 135 and VCC 324, respectively. Such a trend has been only observed in few, very isolated galaxies or at higher redshifts (z &gt; 1). It is thought to be associated with the accretion of metal-poor gas from the intergalactic medium, a mechanism that would be less likely to occur in a high-density environment like Virgo. We combine emission-line observations with deep optical images to investigate the origin of the peculiar metallicity gradient. The presence of weak underlying substructures in both galaxies and the analysis of morphological diagnostics and ionized gas kinematics suggest that the inflow of metal-poor gas to the central regions of the dwarfs may be related to a recent merging event with a gas-rich companion.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2020MNRAS.498.1939G/abstract
ADS Bibcode: 
2020MNRAS.498.1939G
Keywords: 
galaxies: dwarf;galaxies: evolution;galaxies: interactions;galaxies: ISM;galaxies: kinematics and dynamics;galaxies: star formation;Astrophysics - Astrophysics of Galaxies