Seminário "Dilaton gravity, (quasi-)black holes, and scalar charge"

Nesta quarta-feira, 11/12/2013, às 11 horas, no Auditório da Pós-Graduação em Física, teremos o seminário "Dilaton gravity, (quasi-)black holes, and scalar charge", a ser ministrado pelo Prof. Kirill A. Bronnikov (VNIIMS - Rússia). Todos estão convidados.

Resumo

“We consider static electrically charged dust configurations in the framework of Einstein-
Maxwell-dilaton gravity with the interaction $P(\chi) F_{mn} F^{mn}$ in the Lagrangian, where $P(\chi)$ is an arbitrary function of the dilaton field $\chi$, and the latter is allowed to be normal or phantom. It is shown that, for any regular $P(\chi)$, static configurations are possible with arbitrary functions $g_{00} = \e^{2\gamma(x^i)}$ ($i=1,2,3$) and $\chi = \chi(\gamma)$, without any assumption of spatial symmetry. The corresponding matter, electric charge and scalar charge densities are found from the field equations. Meanwhile, configurations with nontrivial $\chi(x^i)$ generically require a nonzero scalar charge density distribution. The classical Majumdar-Papapetrou (MP) system is obtained as a special case where $\chi = \const$; there is its scalar analogue in the case $F\mn = 0$, but only with a phantom $\chi$ field. Among possible solutions are black-hole (BH) and quasi-black-hole (QBH) ones. Some general results on QBH properties obtained previously for the MP system are here extended to systems with the dilaton. Particular examples of asymptotically flat spherically symmetric BH and QBH solutions are found, some of them being phantom-free, that is, exist with a normal $\chi$ field and positive matter density.”