  The impact of ram pressure stripping (RPS) on galaxy evolution has been
studied for over forty years. Recent multi-wavelength data have revealed many
examples of galaxies undergoing RPS, often accompanied with multi-phase tails.
As energy transfer in the multi-phase medium is an outstanding question in
astrophysics, RPS galaxies are great objects to study. Despite the recent burst
of observational evidence, the relationship between gas in different phases in
the RPS tails is poorly known. Here we report, for the first time, a strong
linear correlation between the X-ray surface brightness (SB$_{\rm X}$) and the
H$\alpha$ surface brightness (SB$_{\rm H\alpha}$) of the diffuse gas in the RPS
tails at $\sim$ 10 kpc scales, as SB$_{\rm X}$/SB$_{\rm H\alpha} \sim$ 3.6.
This discovery supports the mixing of the stripped interstellar medium (ISM)
with the hot intracluster medium (ICM) as the origin of the multi-phase RPS
tails. The established relation in stripped tails, also in comparison with the
likely similar correlation in similar environments like X-ray cool cores and
galactic winds, provides an important test for models of energy transfer in the
multi-phase gas. It also indicates the importance of the H$\alpha$ data for our
understanding of the ICM clumping and turbulence.
