The XXL Survey IV. Mass-temperature relation of the bright cluster sample

Lieu, M, Smith, GP, Giles, PA, Ziparo, F, Maughan, BJ, Démoclès, J, Pacaud, F, Pierre, M, Adami, C, Bahé, YM, Clerc, N, Chiappetti, L, Eckert, D, Ettori, S, Lavoie, S, Fevre, J-PL, McCarthy, IG, Kilbinger, M, Ponman, TJ, Sadibekova, T and Willis, JP (2015) The XXL Survey IV. Mass-temperature relation of the bright cluster sample. Astronomy and Astrophysics. ISSN 0004-6361

The XXL survey is the largest survey carried out by XMM-Newton. Covering an area of 50deg$^2$, the survey contains $\sim450$ galaxy clusters out to a redshift $\sim$2 and to an X-ray flux limit of $\sim5\times10^{-15}erg\,s^{-1}cm^{-2}$. This paper is part of the first release of XXL results focussed on the bright cluster sample. We investigate the scaling relation between weak-lensing mass and X-ray temperature for the brightest clusters in XXL. The scaling relation is used to estimate the mass of all 100 clusters in XXL-100-GC. Based on a subsample of 38 objects that lie within the intersection of the northern XXL field and the publicly available CFHTLenS catalog, we derive the $M_{WL}$ of each system with careful considerations of the systematics. The clusters lie at $0.1<z<0.6$ and span a range of $T\simeq1-5keV$. We combine our sample with 58 clusters from the literature, increasing the range out to 10keV. To date, this is the largest sample of clusters with $M_{WL}$ measurements that has been used to study the mass-temperature relation. The fit ($M\propto T^b$) to the XXL clusters returns a slope $b=1.78^{+0.37}_{-0.32}$ and intrinsic scatter $\sigma_{\ln M|T}\simeq0.53$; the scatter is dominated by disturbed clusters. The fit to the combined sample of 96 clusters is in tension with self-similarity, $b=1.67\pm0.12$ and $\sigma_{\ln M|T}\simeq0.41$. Overall our results demonstrate the feasibility of ground-based weak-lensing scaling relation studies down to cool systems of $\sim1keV$ temperature and highlight that the current data and samples are a limit to our statistical precision. As such we are unable to determine whether the validity of hydrostatic equilibrium is a function of halo mass. An enlarged sample of cool systems, deeper weak-lensing data, and robust modelling of the selection function will help to explore these issues further.