The PostgreSQL Global Development Group core team is composed of five long-time community members with various specialisations. Their roles include:
The core team avoids involvement in topics that are best dealt with in an open forum, like technical direction and advocacy. Core team members are appointed by existing core team members.
The core team members are listed on the Contributor Profiles page.
You can contact the core team by emailing pgsql-core [at] postgresql [dot] org.