We present results from two observations ( combined exposure of \sim 17 ksec ) of galaxy cluster Abell 2218 using the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory that were taken on October 19 , 1999 .
Using a Raymond-Smith single temperature plasma model corrected for galactic absorption we find a mean cluster temperature of kT = 6.9 \pm 0.5 kev , metallicity of 0.20 \pm 0.13 ( errors are 90 \% CL ) and rest-frame luminosity in the 2 - 10 kev energy band of 6.2 \times 10 ^ { 44 } erg s ^ { -1 } in a \Lambda CDM cosmology with H _ { 0 } = 65 km s ^ { -1 } Mpc ^ { -1 } .
The brightness distribution within 4 ^ { \prime } .2 of the cluster center is well fit by a simple spherical beta model with core radius 66 ^ { \prime \prime } .4 and \beta = 0.705 .
High resolution Chandra data of the inner 2 ^ { \prime } of the cluster show the x-ray brightness centroid displaced \sim 22 ^ { \prime \prime } from the dominant cD galaxy and the presence of azimuthally asymmetric temperature variations along the direction of the cluster mass elongation .
X-ray and weak lensing mass estimates are in good agreement for the outer parts ( r > 200 h ^ { -1 } ) of the cluster ; however , in the core the observed temperature distribution can not reconcile the x-ray and strong lensing mass estimates in any model in which the intracluster gas is in thermal hydrostatic equilibrium .
Our x-ray data are consistent with a scenario in which recent merger activity in A2218 has produced both significant non-thermal pressure in the core and substructure along the line of sight ; each of these phenomena probably contributes to the difference between lensing and x-ray core mass estimates .