We report on the discovery of a very distant galaxy cluster serendipitously detected in the archive of the XMM- Newton mission , within the scope of the XMM-Newton Distant Cluster Project ( XDCP ) .
XMMUJ0044.0-2033 was detected at a high significance level ( 5 \sigma ) as a compact , but significantly extended source in the X-ray data , with a soft-band flux f ( r < 40 \arcsec ) = ( 1.5 \pm 0.3 ) \times 10 ^ { -14 } erg s ^ { -1 } cm ^ { 2 } .

Optical/NIR follow-up observations confirmed the presence of an overdensity of red galaxies matching the X-ray emission .
The cluster was spectroscopically confirmed to be at z =1.579 using ground-based VLT/FORS2 spectroscopy .
The analysis of the I-H colour-magnitude diagram shows a sequence of red galaxies with a colour range [ 3.7 < I-H < 4.6 ] within 1 \arcmin from the cluster X-ray emission peak .
However , the three spectroscopic members ( all with complex morphology ) have significantly bluer colours relative to the observed red-sequence .
In addition , two of the three cluster members have [ OII ] emission , indicative of on-going star formation .

Using the spectroscopic redshift we estimated the X-ray bolometric luminosity , L _ { bol, 40 \arcsec } \sim 5.8 \times 10 ^ { 44 } erg s ^ { -1 } , implying a massive galaxy cluster .
This places XMMU J0044.0-2033 at the forefront of massive distant clusters , closing the gap between lower redshift systems and recently discovered proto- and low-mass clusters at z > 1.6 .