We present a joint weak-lensing/X-ray study of galaxy cluster mass-observable scaling relations , motivated by the critical importance of accurate calibration of mass proxies for future X-ray missions , including eROSITA .
We use a sample of 12 clusters at z \simeq 0.2 that we have observed with Subaru and XMM-Newton to construct relationships between the weak-lensing mass ( M ) and three X-ray observables : gas temperature ( T ) , gas mass ( M _ { gas } ) , and quasi-integrated gas pressure ( Y _ { X } ) at overdensities of \Delta = 2500 , 1000 , and 500 with respect to the critical density .
We find that M _ { gas } at \Delta \leq 1000 appears to be the most promising mass proxy of the three because it has the lowest intrinsic scatter in mass at fixed observable , \sigma _ { \ln M } \simeq 0.1 , independent of the cluster dynamical state .
The scatter in mass at fixed T and Y _ { X } is a factor of \sim 2 - 3 larger than at fixed M _ { gas } , which are indicative of the structural segregation that we find in the M - T and M - Y _ { X } relationships .
Undisturbed clusters are found to be \sim 40 \% and \sim 20 \% more massive than disturbed clusters at fixed T and Y _ { X } respectively at \sim 2 \sigma significance .
In particular , A 1914 – a well-known merging cluster – significantly increases the scatter and lowers the normalization of the relation for disturbed clusters .
We also investigated the covariance between intrinsic scatter in M - M _ { gas } and M - T relations , finding that they are positively correlated .
This contradicts the adaptive mesh refinement simulations that motivated the idea that Y _ { X } may be a low scatter mass proxy , and agrees with more recent smoothed particle hydrodynamic simulations based on the Millennium Simulation .
We also propose a method to identify a robust mass proxy based on principal component analysis .
The statistical precision of our results is limited by the small sample size and the presence of the extreme merging cluster in our sample .
We therefore look forward to studying a larger , more complete sample in the future .