Franchetto, Andrea (2018) Ionized gas metallicity in galaxies from GASP survey. [Magistrali biennali]
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This thesis is performed in the context of GAs Stripping Phenomena in galaxies with MUSE (GASP) survey. The high-quality spectroscopic data provided by MUSE allow a spatially-resolved study of the ionized gas chemical abundance. This work aims to compare the gas-phase metallicity properties of 10 disk galaxies with no morphological anomalies and 12 gas-stripped galaxies with evident signs of unilateral debris and gas tails. The chemical abundance of the ionized gas is estimated analyzing the emission line fluxes in star-forming regions using the theoretical calibrator pyqz based on photoionization models. The analysis of the metallicity distribution derived in this work confirms that the normal galaxies are characterized by a clear negative gradient. Moreover, the gas-stripped galaxies also exhibit a negative metallicity gradient in the main galaxy body, though it is flatter, that continues in the gas tails. This suggests that the gas-removal process in these galaxies, mainly the ram-pressure stripping, eradicates the gas proceeding outside-in. This work focuses also on the dependence of the metallicity on the global and local properties of galaxies, finding that the local chemical abundance of normal galaxies presents a clear correlation with the stellar mass density, while in gas-stripped galaxies there is a mismatch between these quantities. The results in this work allow to improve the knowledge of the ram-pressure mechanism demonstrating that the gas-phase metallicity can trace the gas-stripping history.
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