Abell 1689 is a galaxy cluster at z = 0.183 where previous measurements of its mass using various techniques gave discrepant results .
We present a new detailed measurement of the mass with the data based on X-ray observations with the European Photon Imaging Camera aboard the XMM-Newton Observatory , determined by using an unparameterized deprojection technique .
Fitting the total mass profile to a Navarro-Frenk-White model yields halo concentration c = 7.2 ^ { +1.6 } _ { -2.4 } and r _ { 200 } = 1.13 \pm 0.21 ~ { } h ^ { -1 } ~ { } \mathrm { Mpc } , corresponding to a mass which is less than half of what is found from gravitational lensing .
Adding to the evidence of substructure from optical observations , X-ray analysis shows a highly asymmetric temperature profile and a non-uniform redshift distribution implying large scale relative motion of the gas .
A lower than expected gas mass fraction f _ { gas } = 0.072 ~ { } \pm~ { } 0.008 ( for a flat \Lambda CDM cosmology ) suggests a complex spatial and/or dynamical structure .
We also find no signs of any additional absorbing component previously reported on the basis of the Chandra data , confirming the XMM low energy response using data from ROSAT .