The discovery of primeval large-scale structures with forming clusters at redshift 6

We report the discovery of primeval large- scale structures ( LSSs) including two protoclusters in a forming phase at. We carried out extensive deep narrowband imaging in the 1 deg(2) sky of the Subaru/ XMM- Newton Deep at z = 5.7 Field and obtained a cosmic map of 515 Lyalpha emitters ( LAEs) in a volume with a transverse dimension of and a depth of similar to 40 Mpc in comoving units. This cosmic map shows filamentary LSSs, including 180 Mpc x 180 Mpc clusters and surrounding 10 - 40 Mpc scale voids, similar to the present- day LSSs. Our spectroscopic follow- up observations identify overdense regions in which two dense clumps of LAEs with a sphere of 1 Mpc diameter in physical units are included. These clumps show about 130 times higher star formation rate density, mainly due to a large overdensity, similar to 80, of LAEs. These clumps would be clusters in a formation phase involving a burst of galaxy formation.