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MUSE sneaks a peek at extreme ram-pressure stripping events – II. The physical properties of the gas tail of ESO137−001.

Fossati, M. and Fumagalli, M. and Boselli, A. and Gavazzi, G. and Sun, M. and Wilman, D.J. (2016) 'MUSE sneaks a peek at extreme ram-pressure stripping events – II. The physical properties of the gas tail of ESO137−001.', Monthly notices of the Royal Astronomical Society., 455 (2). pp. 2028-2041.

Abstract

We present a study of the physical properties of the disc and tail of ESO137−001, a galaxy suffering from extreme ram-pressure stripping during its infall into the Norma cluster. With sensitive and spatially resolved MUSE (Multi Unit Spectroscopic Explorer) spectroscopy, we analyse the emission line diagnostics in the tail of ESO137−001, finding high values of [N II]/Hα and [O I]/Hα that are suggestive of the presence of shocks in turbulent gas. However, the observed line ratios are not as strong as commonly seen in pure shock heating models, suggesting that other emission mechanisms may contribute to the observed emission. Indeed, part of the observed emission, particularly at close separations from the galaxy disc, may originate from recombination of photoionized gas stripped from the main body of ESO137−001. We also identify a large number of bright compact knots within in the tail, with line ratios characteristic of H II regions. These H II regions, despite residing in a stripped gas tail, have quite typical line ratios, densities, temperatures, and metallicity (∼0.7 solar). The majority of these H II regions are embedded within diffuse gas from the tail, which is dynamically cool (σ ∼ 25–50 km s− 1). This fact, together with a lack of appreciable gradients in age and metallicity, suggests that these H II regions formed in situ. While our analysis represents a first attempt to characterize the rich physics of the ESO137−001 tail, future work is needed to address the importance of other mechanisms, such as thermal conduction and magnetohydrodynamic waves, in powering the emission in the tail.

Item Type:Article
Keywords:Shock waves, techniques: spectroscopic, H II regions, Galaxies: abundances, Galaxies: clusters: individual: ESO137−001, Galaxies: ISM.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1093/mnras/stv2400
Publisher statement:This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:14 October 2015
Date deposited:14 December 2015
Date of first online publication:19 November 2015
Date first made open access:No date available

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