Have Arsenal really signed the Argentinian superstar Ricky Alvarez?

There have been numerous Arsenal rumours around the web stating that the Gunners have signed the free-agent Ricky Alvarez whose contract is up at Velez-Sarsfield in Argentina. He is currently playing for Sarsfield in the Copa Libertores and the Clausura and (so it goes) he can't reveal the deal until the club are out of [.