Former Federal Reserve chairman Ben Bernanke is joining bond giant Pimco as a senior adviser, as the firm seeks to bolster its star power following the departure of co-founder Bill Gross. The move may be questioned by some competitors who had criticized the Fed during Bernanke’s reign for being too close to Pimco, whose full name is Pacific Investment Management Co. The critics suggested that could have potentially given the Newport Beach, California-based firm an advantage in interpreting monetary policy.