A Small-Scale Investigation of Molecular Emission toward the Tip of the
  Western Lobe of W50/SS433
  We perform a molecular (CO and CN) line observation using IRAM 30m telescope
toward two small regions near the western edge of supernova remnant (SNR)
W50/SS433. CO observation reveals spatial correspondence of two molecular
clumps at the local-standard-of-rest (LSR) velocity around +53 km s$^{-1}$ with
multiwavelength local features of W50/SS433 system. One of the two clumps
appears to be embedded in a void of diffuse radio and X-ray emission. Toward
the two clumps, asymmetric broad line profiles of the $^{12}$CO lines are
obtained, which provide kinematic evidence of the association between the
clumps and the jet-related gas. The $^{12}$CO $J=2-1$/$J=1-0$ line ratios ($>
0.9$) and the kinetic temperatures ($\sim 30$ K) of the clumps are
distinctively higher than all those of the clumps at other LSR velocities along
the same line of sight, which may be physical signatures of the association. We
show that the clump coincident with the void can survive the thermal heating if
it is surrounded by hot gas, with an evaporation timescale much larger than the
age of SNR W50. We also show that the thermal equilibrium in the high
temperature clumps can be maintained by the heating of the penetrating
environmental CRs. CN ($J=3/1-1/2$) line emission is detected in the two
clumps, and the CN abundances derived are much higher than that in the
interstellar molecular clouds (MCs) and that in the SNR-interacting MCs.
