Response of an Unruh-DeWitt detector near an extremal black hole

We consider the response of an Unruh-DeWitt detector near extremal charged black hole, modeling near-horizon region this spacetime by Bertotti-Robinson spacetime. The advantage employing limit is that two-point functions for a massless scalar field are obtainable in closed form number quantum states interest. coupled to both Boulware vacuum state and arbitrary thermal states, including Hartle-Hawking state, analyse detector's broad range trajectories. Particular attention paid thermalization detector, anti-Unruh anti-Hawking effect.