Star formation histories in mergers: the spatially resolved properties of the early-stage merger luminous infrared galaxies IC 1623 and NGC 6090

DOI: 
10.1093/mnras/stx383
Publication date: 
01/06/2017
Main author: 
Cortijo-Ferrero, C.
IAA authors: 
Cortijo-Ferrero, C.;González Delgado, R. M.;Pérez, E.;García-Benito, R.;López Fernández, R.
Authors: 
Cortijo-Ferrero, C.;González Delgado, R. M.;Pérez, E.;Cid Fernandes, R.;Sánchez, S. F.;de Amorim, A. L.;Di Matteo, P.;García-Benito, R.;Lacerda, E. A. D.;López Fernández, R.;Tadhunter, C.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Volume: 
467
Pages: 
3898-3919
Abstract: 

The role of major mergers in galaxy evolution is investigated through a detailed characterization of the stellar populations, ionized gas properties and star formation rates (SFR) in the early-stage merger luminous infrared galaxies (LIRGs) IC 1623 W and NGC 6090, by analysing optical integral field spectroscopy and high-resolution Hubble Space Telescope imaging. The spectra were processed with the starlight full spectral fitting code, and the emission lines measured in the residual spectra. The results are compared with non-interacting control spiral galaxies from the Calar Alto Legacy Integral Field Area survey. Merger-induced star formation is extended and recent, as revealed by the young ages (50-80 Myr) and high contributions to light of young stellar populations (50-90 per cent), in agreement with merger simulations in the literature. These early-stage mergers have positive central gradients of the stellar metallicity, with an average ∼0.6 Z<SUB>☉</SUB>. Compared to non-interacting spirals, they have lower central nebular metallicity, and flatter profiles, in agreement with the gas inflow scenario. We find that they are dominated by star formation, although shock excitation cannot be discarded in some regions, where high velocity dispersion is found (170-200 km s<SUP>-1</SUP>). The average SFR in these early-stage mergers (∼23-32 M<SUB>☉</SUB> yr<SUP>-1</SUP>) is enhanced with respect to main-sequence Sbc galaxies by factors of 6-9, slightly above the predictions from classical merger simulations, but still possible in about 15 per cent of major galaxy mergers, where U/LIRGs belong.

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022202329&doi=10.1093%2fmnras%2fstx383&partnerID=40&md5=7f1d84ba9a98971ae1b47169ceb443d4
ADS Bibcode: 
2017MNRAS.467.3898C
Keywords: 
techniques: spectroscopic;galaxies: evolution;galaxies: interactions;galaxies: ISM;galaxies: star formation;galaxies: stellar content;Astrophysics - Astrophysics of Galaxies