We use multifrequency matched filters to estimate , in the WMAP 5-year data , the Sunyaev–Zel ’ dovich ( SZ ) fluxes of 893 ROSAT NORAS/REFLEX clusters spanning the luminosity range L _ { X, [ 0.1 - 2.4 ] { keV } } = 2 \times 10 ^ { 41 } -3.5 \times 10 ^ { 45 } erg s ^ { -1 } .
The filters are spatially optimised by using the universal pressure profile recently obtained from combining XMM-Newton observations of the REXCESS sample and numerical simulations .
Although the clusters are individually only marginally detected , we are able to firmly measure the SZ signal ( > 10 \sigma ) when averaging the data in luminosity/mass bins .
The comparison between the bin-averaged SZ signal versus luminosity and X-ray model predictions shows excellent agreement , implying that there is no deficit in SZ signal strength relative to expectations from the X-ray properties of clusters .
Using the individual cluster SZ flux measurements , we directly constrain the Y _ { 500 } - L _ { X } and Y _ { 500 } - M _ { 500 } relations , where Y _ { 500 } is the Compton y–parameter integrated over a sphere of radius r _ { 500 } .
The Y _ { 500 } – M _ { 500 } relation , derived for the first time in such a wide mass range , has a normalisation Y ^ { * } _ { 500 } = \left [ 1.60 \pm 0.19 \right ] \times 10 ^ { -3 } { arcmin } ^ { 2 } at M _ { 500 } = 3 \times 10 ^ { 14 } h ^ { -1 } M _ { \odot } , in excellent agreement with the X-ray prediction of 1.54 \times 10 ^ { -3 } { arcmin } ^ { 2 } , and a mass exponent of \alpha = 1.79 \pm 0.17 , consistent with the self-similar expectation of 5 / 3 .
Constraints on the redshift exponent are weak due to the limited redshift range of the sample , although they are compatible with self-similar evolution .