Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 160; Flight Crew Type 16000
Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural FAR
Flight Crew Overcame Equipment Problem
Company Policy; Human Factors; Procedure
While at cruise Dispatch notified us via ACARS that we had HAZMAT (a battery) onboard; which we were not made aware of nor given paperwork prior to departure.
On Date; on Aircraft X from ZZZ to ZZZ1; about halfway through the flight; we received an ACARS message from Dispatch that we were carrying HAZMAT. The Captain and I were unaware of that; and this was our first notification. Apparently; we were carrying a battery that was considered HAZMAT; but we were not told or given any paperwork prior to departure from ZZZ.
Air Carrier flight crew reported airborne notification of undeclared Hazmat.  Hazmat cargo loaded on aircraft without providing flight crew the required Hazmat documentation or flight crew notification.