Spatially resolved integral field spectroscopy of the ionized gas in IZw18
| Autor: | Jarle Brinchmann, C. Kehrig, D. Kunth, José M. Vílchez, J. D. Hernández-Fernández, Jorge Iglesias-Páramo, Florence Durret, Enrique Pérez-Montero, S. Duarte Puertas |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Physics
Spatially resolved FOS: Physical sciences Astronomy and Astrophysics Astrophysics Plasma Astrophysics - Astrophysics of Galaxies 01 natural sciences Galaxy Knot (unit) Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Ionization 0103 physical sciences Homogeneity (physics) Field spectroscopy Emission spectrum Atomic physics 010306 general physics 010303 astronomy & astrophysics |
| Zdroj: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 459, 2992-3004 |
| Popis: | We present a detailed 2D study of the ionized ISM of IZw18 using new 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 (~ 1.4 kpc x 1.4 kpc) 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 NW knot and thereabouts. We detect a Wolf-Rayet feature near the NW knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity-indicator R23 and the ionization parameter (as traced by [OIII]/[OII]) across IZw18. Over ~ 0.30 kpc^2, using the [OIII]4363 line, we compute Te[OIII] values (~ 15000 - 25000 K), and oxygen abundances are derived from the direct determinations of Te[OIII]. More than 70% of the higher-Te[OIII] (> 22000 K) spaxels are HeII4686-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. Accepted for publication in MNRAS, 13 pages, 10 figures, 4 tables |
| Databáze: | OpenAIRE |
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