Cluster Mass Estimate Using Strong Gravitational Lenses Revisited

To study clusters of galaxies, the cluster mass is one of the most important quantities. However, it has been recognized that there exists more than a factor of 2 difference between the mass determined from X-ray observations (X-ray mass) and that from strong lensing effects (lensing mass). Intending to solve the discrepancy, we examined the means of the mass derivation from strong lensing effects. We found that the conventional way could overestimate the mass by 10–30%. In this paper, we present an alternative way to estimate the lensing mass. By our re-analysis, the discrepancy between the lensing mass and the X-ray mass can be reduced. We also discuss the causes of the remaining discrepancy.