2017ApJ...847...79W

We present Chandra observations of hot gas structures, which are characteristic of gas-stripping during infall, in the Virgo cluster elliptical galaxy M60 (NGC4649) located 1 Mpc east of M87. Chandra X-ray images at 0.5-2 keV show a sharp leading edge in the surface brightness that is 12.4 ± 0.1 kpc north and west of the galaxy center in the direction of M87 and 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 an abundance of 0.5 Z_☉ inside the edge and 1.37_–0.19^+0.35 keV for an abundance of 0.1 Z_☉ in the Virgo ICM free stream region. We find that the observed jump in surface brightness yields a density ratio n_in/n_out=6.44_–0.67^+1.04 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_–1.4^+1.7 and Mach number of 1.7_–0.3^+0.3. For 1.37 keV Virgo gas, we find a total infall velocity for M60 of v_M60=1030±180 km s^–1. We calculate the motion in the plane of the sky to be v_tran=1012_–192⁺¹⁸³ km s^–1, implying an inclination angle of ξ=11_–3⁺³°. Surface brightness profiles also 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.