One loop determinant in the extremal black hole from quasinormal modes

Abstract: In this paper, we evaluate the one loop partition function of a scalar field in the near horizon geometry of the extremal Reissner Nordstr\"{o}m black hole from an infinite product over quasinormal modes using the Denef-Hartnoll-Sachdev (DHS) formula. We show that, the logarithmic divergent term of the one loop partition function computed using the DHS formula agrees with the heat kernel method. Using the same formula, we also evaluate the one loop partition function of scalar field in the near extremal Kerr Newman black hole and observe that it reduces to the same in the near horizon $AdS_2\times S^2$ geometry of the extremal Reissner Nordstr\"{o}m black hole when the angular velocity at the horizon is tuned to $2\pi T_{BH}$ value. We observe that, for higher spin fields, the mode functions become irregular at the horizon for certain quasinormal frequencies and therefore we remove them to obtain the one loop determinant.