Galaxy gas flows inferred from a detailed, spatially resolved metal budget
Monthly Notices of the Royal Astronomical Society
Oxford University Press
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Belfiore, F., Maiolino, R., & Bothwell, M. (2015). Galaxy gas flows inferred from a detailed, spatially resolved metal budget. Monthly Notices of the Royal Astronomical Society, 455 1218-1236. https://doi.org/10.1093/mnras/stv2332
We use the most extensive integral field spectroscopic map of a local galaxy, NGC 628, combined with gas and stellar mass surface density maps, to study the distribution of metals in this galaxy out to 3 effective radii (Rₑ). At each galactocentric distance, we compute the metal budget and thus constrain the mass of metals lost. We find that in the disc about 50% of the metals have been lost throughout the lifetime of the galaxy. The fraction of metals lost is higher in the bulge (∼70%) and decreases towards the outer disc (∼ 3 Rₑ). In contrast to studies based on the gas kinematics, which are only sensitive to ongoing outflow events, our metal budget analysis enables us to infer the average outflow rate during the galaxy lifetime. By using simple physically motivated models of chemical evolution we can fit the observed metal budget at most radii with an average outflow loading factor of order unity, thus clearly demonstrating the importance of outflows in the evolution of disc galaxies of this mass range (log(M_*/M_⊙ ) ∼ 10). The observed gas phase metallicity is higher than expected from the metal budget and suggests late-time accretion of enriched gas, likely raining onto the disc from the metal-enriched halo.
galaxies: abundances, galaxies: evolution, galaxies: fundamental parameters, galaxies: individual
FB acknowledges support from the United Kingdom Science and Technology Facilities Council. This work makes use of THINGS (‘The Nearby Galaxy Survey’, Walter et al. 2008), HERACLES (the ‘HERA CO line Extragalactic Survey’, Leroy et al. 2009) and PINGS (the ‘PPAK IFS Nearby Galaxy Survey’, Rosales-Ortega et al. 2010). We acknowledge the contribution from the referee in improving the content and the clarity of the paper. We thank Fiorenzo Vincenzo and Francesca Matteucci for their invaluable help in interpreting the vast literature on chemical abundance modelling and nucleosynthetic yields. We also thank Ying-jie Peng for support and discussion on development of his chemical evolution models. We wish to thank Fabian Rosales-Ortega for kindly sharing the PINGS data on NGC 628 and for his encouragement and feedback on the early stages of this work. We thank Matt Auger for useful discussions and healthy skepticism and the participants to the MPIA summer workshop ‘A 3D view on galaxies evolution: from statistics to physics’ for insightful comments.
External DOI: https://doi.org/10.1093/mnras/stv2332
This record's URL: https://www.repository.cam.ac.uk/handle/1810/251373