The nature of the most distant radio source known at z=7.0 comma a blazar

Relativistic jets are thought to play a key role on the formation of massivegalaxies and supermassive black holes. Radio and Xray observations provide themost direct probes of SMBHs accretion mechanisms and jets physics. However,currently there is a dearth of radio sources at z>7, which in turn are a keymissing population for future 21 cm absorption studies well within the epoch ofreionization. We propose quasicontemporary VLA/XMM observations of a newredshiftrecord radio source at z7, for which archival nonsimultaneous 1.4 and3.0GHz data reveal an atypical sharply rising spectrum of index +0.6 that couldbe compatible with a blazar. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]