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

Fossati, M.; Fumagalli, M.; Boselli, A.; Gavazzi, G.; Sun, M.; Wilman, D.J.

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.

Citation

Fossati, M., Fumagalli, M., Boselli, A., Gavazzi, G., Sun, M., & Wilman, D. (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), 2028-2041. https://doi.org/10.1093/mnras/stv2400

• Journal Article Type: Article
• Acceptance Date: Oct 14, 2015
• Online Publication Date: Nov 19, 2015
• Publication Date: Jan 11, 2016
• Deposit Date: Dec 13, 2015
• Publicly Available Date: Dec 14, 2015
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 455
• Issue: 2
• Pages: 2028-2041
• DOI: https://doi.org/10.1093/mnras/stv2400
• Keywords: Shock waves, techniques: spectroscopic, H II regions, Galaxies: abundances, Galaxies: clusters: individual: ESO137−001, Galaxies: ISM.
• Public URL: https://durham-repository.worktribe.com/output/1396347
• Related Public URLs: http://adsabs.harvard.edu/abs/2016MNRAS.455.2028F