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The narrow X-ray tail and double Hα tails of ESO 137-002 in A3627

Zhang, B.; Sun, M.; Ji, L.; Sarazin, C.; Lin, X. B.; Nulsen, P. E. J.; Roediger, E.; Donahue, M.; Forman, W.; Jones, C.; Voit, G. M.; Kong, X.


B. Zhang

M. Sun

L. Ji

C. Sarazin

X. B. Lin

P. E. J. Nulsen

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Dr Elke Roediger
Reader in Astrophysics, Director of the E.A. Milne Centre for Astrophysics

M. Donahue

W. Forman

C. Jones

G. M. Voit

X. Kong


We present the analysis of a deep Chandra observation of a ~2 L * late-type galaxy, ESO 137-002, in the closest rich cluster A3627. The Chandra data reveal a long (gsim40 kpc) and narrow tail with a nearly constant width (~3 kpc) to the southeast of the galaxy, and a leading edge ~1.5 kpc from the galaxy center on the upstream side of the tail. The tail is most likely caused by the nearly edge-on stripping of ESO 137-002's interstellar medium (ISM) by ram pressure, compared to the nearly face-on stripping of ESO 137-001 discussed in our previous work. Spectral analysis of individual regions along the tail shows that the gas throughout it has a rather constant temperature, ~1 keV, very close to the temperature of the tails of ESO 137-001, if the same atomic database is used. The derived gas abundance is low (~0.2 solar with the single-kT model), an indication of the multiphase nature of the gas in the tail. The mass of the X-ray tail is only a small fraction (<5%) of the initial ISM mass of the galaxy, suggesting that the stripping is most likely at an early stage. However, with any of the single-kT, double-kT, and multi-kT models we tried, the tail is always "over-pressured" relative to the surrounding intracluster medium (ICM), which could be due to the uncertainties in the abundance, thermal versus non-thermal X-ray emission, or magnetic support in the ICM. The Hα data from the Southern Observatory for Astrophysical Research show a ~21 kpc tail spatially coincident with the X-ray tail, as well as a secondary tail (~12 kpc long) to the east of the main tail diverging at an angle of ~23° and starting at a distance of ~7.5 kpc from the nucleus. At the position of the secondary Hα tail, the X-ray emission is also enhanced at the ~2σ level. We compare the tails of ESO 137-001 and ESO 137-002, and also compare the tails to simulations. Both the similarities and differences of the tails pose challenges to the simulations. Several implications are briefly discussed.


Zhang, B., Sun, M., Ji, L., Sarazin, C., Lin, X. B., Nulsen, P. E. J., …Kong, X. (2013). The narrow X-ray tail and double Hα tails of ESO 137-002 in A3627. The Astrophysical journal, 777(2), Article 122.

Journal Article Type Article
Acceptance Date Aug 29, 2013
Online Publication Date Oct 22, 2013
Publication Date Nov 10, 2013
Deposit Date Mar 1, 2016
Publicly Available Date Mar 1, 2016
Journal Astrophysical journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 777
Issue 2
Article Number 122
Keywords X-ray tails
Public URL
Publisher URL;
Additional Information This is a copy of an article published in the Astrophysical journal, 2013, v.777 issue 2.


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© 2016. The American Astronomical Society. All rights reserved.

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