2019, no. 3

### POLISH DOUGHNUTS IN GUTSUNAEV–MANKO SPACETIME

#### Kichigin I.V., Tegai S.F.

We consider the polish doughnut accretion disk model in the Gutsunaev–Manko spacetime. This axially symmetric asymptotically flat solution of the Einstein–Maxwell equations can be viewed as the exterior field of the massive magnetic dipole. The matter of the accretion disk in the polish doughnut model is described by the perfect fluid stress-energy tensor. The disk gravity is considered negligible. By integrating the relativistic Euler equation one can find the equipressure surfaces without defining the equation of state of the disk matter. The structure of the polish doughnut obtained in such a way depends on the disk angular momentum distribution. We consider two types of angular momentum distributions. The first is a constant angular momentum, which is typical for the black hole accretion. The second grows monotonously from zero on the star surface to the keplerian momentum at infinity characteristically for the neutron star accretion. With the realistic values of the star parameters the influence of the magnetic field remains small, however the extremely large magnetic momentum or compactness can lead to the qualitative changes in the structure of the accretion disk.

Keywords: accretion, polish doughnut, magnetic field.

UDC: 524.3

PACS: 95.30.Sf, 97.10.Gz

DOI: 10.17238/issn2226-8812.2019.3.77-87