By cross-correlating templates constructed from the 2 Micron All Sky Survey ( 2MASS ) Extended Source ( XSC ) catalogue with WMAP ’ s first year data , we search for the thermal Sunyaev-Zel ’ dovich signature induced by hot gas in the local Universe .
Assuming that galaxies trace the distribution of hot gas , we select regions on the sky with the largest projected density of galaxies .
Under conservative assumptions on the amplitude of foreground residuals , we find a temperature decrement of -35 \pm 7 \mu K ( \sim 5 \sigma detection level , the highest reported so far ) in the \sim 26 square degrees of the sky containing the largest number of galaxies per solid angle .
We show that most of the reported signal is caused by known galaxy clusters which , when convolved with the average beam of the WMAP W band channel , subtend a typical angular size of 20–30 arcmins .
Finally , after removing from our analyses all pixels associated with known optical and X-ray galaxy clusters , we still find a tSZ decrement of -96 \pm 37 \mu K in pixels subtending about \sim 0.8 square degrees on the sky .
Most of this signal is coming from five different cluster candidates in the Zone of Avoidance ( ZoA ) , present in the Clusters In the ZoA ( CIZA ) catalogue .
We found no evidence that structures less bound than clusters contribute to the tSZ signal present in the WMAP data .