I didn't understand what you mean by system authentication in pega, but below are the authentication you can provide to pega application
Authentication in Pega®Platform ensures that only users and systems whose identity has been verified can access resourcessuch asweb pages, APIs, and data. Sample use cases for authentication in Pega Platform that illustrate different types of resources, users and systems include:
User login– Using a browser, a user logs in to an interactive session in an application that was built using Pega Platform, or a Pega developer logs in to Designer Studio to make changes to an application.
Platform connectors request external services– An application invokes an external REST service to get information from an external system or application, and must provide authentication to this service. The authentication can be done by using assets (such as tokens, certificates, or keys) that are managed by Pega Platform.
Pega Platform services receive external requests for execution– An external system or application invokes a REST service defined in Pega Platform to get case information.
Internal requests for resources among the Pega Platform components that are running on different servers– A user session for an application that is running on a node in a Pega cluster sends SQL queries to the Pega database, forwards a user’s search query to an Elasticsearch node, or sends or asks for information in a cluster-wide store such as Cassandra or Ignite.
Further you can refer below links for more details