Spatially resolved integral field spectroscopy of the ionized gas in IZw18

Author(s)

Kehrig, C. ; Vilchez, J. M. ; Perez-Montero, E. ; Iglesias-Paramo, J. ; Hernandez-Fernandez, J. D. ; Duarte Puertas, S. ; Brinchmann, J. ; Durret, F. ; Kunth, D.

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 459, n. 3, p. 2992-3004, JUL 1 2016.
• Web of Science Citations: 16

Abstract

We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding the properties most closely resembling those prevailing at distant starbursts. Our IFU aperture (similar to 1.4 x 1.4 kpc(2)) samples the entire IZw18 main body and an extended region of its ionized gas. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located close to the north-west knot and thereabouts. We detect a Wolf-Rayet feature near the north-west knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity indicator R-23 and the ionization parameter (as traced by {[}O III]/{[}O II]) across IZw18. Over similar to 0.30 kpc(2), using the {[}O III] lambda 4363 line, we compute T-e{[}O III] values (similar to 15 000-25 000 K), and oxygen abundances are derived from the direct determinations of T-e{[}O III]. More than 70 per cent of the higher-T-e{[}O III] (greater than or similar to 22 000 K) spaxels are He II lambda 4686-emitting spaxels too. From a statistical analysis, we study the presence of variations in the ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the error-weighted mean of 12 + log(O/H) = 7.11 +/- 0.01 is taken as the representative O/H for IZw18. Aperture effects on the derivation of O/H are discussed. Using our IFU data we obtain, for the first time, the IZw18 integrated spectrum. (AU)

• FAPESP's process: 12/13381-0 - Exploring the impact of environmental processes on Clusters and Groups of Galaxies
• Grantee: Jonathan David Hernández Fernández
• Support type: Scholarships in Brazil - Post-Doctorate