Chandra X-ray observations of NGC4342 , a low stellar mass ( M _ { K } = -22.79 mag ) early-type galaxy , show luminous , diffuse X-ray emission originating from hot gas with temperature of kT \sim 0.6 keV .
The observed 0.5 - 2 keV band luminosity of the diffuse X-ray emission within the D _ { 25 } ellipse is L _ { 0.5 - 2 keV } = 2.7 \times 10 ^ { 39 } { erg s ^ { -1 } } .
The hot gas has a significantly broader distribution than the stellar light , and shows strong hydrodynamic disturbances with a sharp surface brightness edge to the northeast and a trailing tail .
We identify the edge as a cold front and conclude that the distorted morphology of the hot gas is produced by ram pressure as NGC4342 moves through external gas .
From the thermal pressure ratios inside and outside the cold front , we estimate the velocity of NGC4342 and find that it moves supersonically ( M \sim 2.6 ) towards the northeast .
Outside the optical extent of the galaxy we detect \sim 17 bright ( L _ { 0.5 - 8 keV } \gtrsim 3 \times 10 ^ { 37 } { erg s ^ { -1 } } ) excess X-ray point sources .
The excess sources are presumably low-mass X-ray binaries ( LMXBs ) located in metal-poor globular clusters ( GCs ) in the extended dark matter halo of NGC4342 .
Based on the number of excess sources and the average frequency of bright LMXBs in GCs , we estimate that NGC4342 may host roughly 850 - 1700 GCs .
In good agreement with this , optical observations hint that NGC4342 may harbor 1200 \pm 500 GCs .
This number corresponds to a GC specific frequency of S _ { N } = 19.9 \pm 8.3 , which is among the largest values observed in full-size galaxies .