Release : 14.x
Component : CA IDENTITY SUITE (VIRTUAL APPLIANCE)
The Synthetic Transaction is the result of Message Health check activities. The Synthetic Transaction mentioned is IM generating activity in the JMS (Java Message Service) as a test.
For details on "Check Message Health" can be found in the CA IM Product documentation (link below)
https://techdocs.broadcom.com/us/en/symantec-security-software/identity-security/identity-manager/14-5/configuring/task-persistence/monitor-health-of-the-task-persistence-database.html