Helicopter pilot reported an NMAC with a UAS. Evasive action was taken by the helicopter pilot to avoid collision.

Narrative

I was the Pilot in Command of a helicopter conducting authorized aerial broadcast operations for the event inside the designated helicopter working area within ZZZ Class B airspace. Prior to the event; all participating aerial assets completed deconfliction briefings with event officials; local police department UAS; and the UAS company. All sanctioned UAS were operating in pre-planned static positions at or below 400 ft AGL; and we maintained continuous visual separation from all known drones throughout the night.At approximately XA12; in the vicinity of the event; our aircraft was at approximately 2;625 ft MSL (about 500 ft AGL) and 103 KIAS. We encountered an unauthorized DJI-type quadcopter at approximately 500 ft AGL directly in our flight path. My Safety Pilot visually acquired the drone and immediately called the hazard. I executed an abrupt pitch-up/climb to avoid impact. The drone passed directly beneath the aircraft with an estimated 15 ft of vertical separation.Two minutes prior to this event; the drone detection company had alerted local police; FAA; and the UAS company of an unauthorized drone over the hotel's parking lot. This detection corresponded with our location and timeline.Following the near miss; we immediately notified event operations to confirm that the drone was not part of the sanctioned UAS team; which was verified. The UAS company then notified FAA; city; and the drone detection company.After the near miss; we avoided the affected area until approximately XA28; at which time we conducted a higher-altitude scan in an effort to visually locate the drone. We were unable to reacquire it and assessed that the drone likely landed or descended shortly after the encounter. After a reasonable effort to ensure the area was clear; we resumed operations with heightened caution and vigilance for the remainder of the mission.No damage occurred to the aircraft; and no additional encounters were observed.