Source : Webster's Revised Unabridged Dictionary (1913)

Unconcerned \Un`con*cerned"\, a.
   Not concerned; not anxious or solicitous; easy in mind;
   carelessly secure; indifferent; as, to be unconcerned at what
   has happened; to be unconcerned about the future. --
   {Un`con*cern"ed*ly}, adv. -- {Un`con*cern"ed*ness}, n.

         Happy mortals, unconcerned for more.     --Dryden.

Source : WordNet®

unconcernedly
     adv : in an unconcerned manner; "war was breaking out in Europe,
           but she unconcernedly planned for a holiday"