The infall of the Virgo elliptical galaxy M60 toward M87 and the gaseous structures produced by Kelvin-Helmholtz instabilities

Wood, R. A.; Jones, C.; Machacek, M. E.; Forman, W. R.; Bogdan, A.; Andrade-Santos, F.; Kraft, R. P.; Paggi, A.; Roediger, E.

Abstract

We present Chandra observations of hot gas structures, characteristic of gas stripping during infall, in the Virgo cluster elliptical galaxy M60 (NGC4649) located 1 Mpc east of M87. 0.5−2 keV Chandra X-ray images show a sharp leading edge in the surface brightness 12.4±0.1 kpc north and west of the galaxy center in the direction of M87 characteristic of a merger cold front due to M60's motion through the Virgo ICM. We measured a temperature of 1.00±0.02 keV for abundance 0.5Z⊙ inside the edge and 1.37+0.35−0.19 keV for abundance 0.1Z⊙ in the Virgo ICM free stream region. We find that the observed jump in surface brightness yields a density ratio of 6.44+1.04−0.67 between gas inside the edge and in the cluster free stream region. If the edge is a cold front due solely to the infall of M60 in the direction of M87, we find a pressure ratio of 4.7+1.7−1.4 and Mach number 1.7±0.3. For 1.37 keV Virgo gas we find a total infall velocity for M60 of 1030±180 kms−1. We calculate the motion in the plane of the sky to be 1012+183−192 km−1 implying an inclination angle ξ=11±3 degrees. Surface brightness profiles show the presence of a faint diffuse gaseous tail. We identify filamentary, gaseous wing structures caused by the galaxy's motion through the ICM. The structure and dimensions of these wings are consistent with simulations of Kelvin-Helmholtz instabilities as expected if the gas stripping is close to inviscid.

Citation

Wood, R. A., Jones, C., Machacek, M. E., Forman, W. R., Bogdan, A., Andrade-Santos, F., Kraft, R. P., Paggi, A., & Roediger, E. (2017). The infall of the Virgo elliptical galaxy M60 toward M87 and the gaseous structures produced by Kelvin-Helmholtz instabilities. The Astrophysical journal, 847(1), Article ARTN 79. https://doi.org/10.3847/1538-4357/aa8723

• Journal Article Type: Article
• Acceptance Date: Jul 11, 2017
• Online Publication Date: Sep 22, 2017
• Publication Date: Sep 22, 2017
• Deposit Date: Apr 17, 2017
• Publicly Available Date: Sep 22, 2017
• Journal: Astrophysical journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 847
• Issue: 1
• Article Number: ARTN 79
• DOI: https://doi.org/10.3847/1538-4357/aa8723
• Keywords: Galaxies : clusters : general; Virgo; Galaxies : individual (NGC 4649, NGC 4647, M60, M87); Galaxies : intergalactic medium; X-rays : galaxies
• Public URL: https://hull-repository.worktribe.com/output/450293
• Publisher URL: http://iopscience.iop.org/article/10.3847/1538-4357/aa8723/meta;jsessionid=544B0BD7BE49F9AC0FD3A83F10370665.c5.iopscience.cld.iop.org
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: The Infall of the Virgo Elliptical Galaxy M60 toward M87 and the Gaseous Structures Produced by Kelvin–Helmholtz Instabilities; Copyright information: © 2017. The American Astronomical Society. All rights reserved.; Date received: 2017-03-03; Date accepted: 2017-07-11; Online publication date: 2017-09-22
• Contract Date: Apr 17, 2017