arXiv subjects

M. Karlovini

Publications and source records attributed to M. Karlovini.

3 recordsLinked to original sources

arXiv2000

Constructing stellar objects with multiple necks

We discuss the construction of perfect fluid stellar objects having optical geometries with multiple necks corresponding to spatially closed unstable lightlike geodesics. We prove that there exist physically reasonable models with arbitrarily many necks. We also show how a first order phase transition can give rise to quite pronounced secondary double necks. The analysis is carried out using a modification of a recent dynamical systems formulation of the TOV equations due to Nilsson and Uggla. Our reformulation allows for a very general family of equations of state including, for example, phase transitions.

gr-qc↗

arXiv2000

Ultracompact stars with multiple necks

We discuss ultracompact stellar objects which have multiple necks in their optical geometry. There are in fact physically reasonable equations of state for which the number of necks can be arbitrarily large. The proofs of these statements rely on a recent regularized formulation of the field equations for static spherically symmetric models due to Nilsson and Uggla. We discuss in particular the equation of state p=ρ-ρ_s which plays a central role in this context.

gr-qc↗

arXiv2000

Compact stellar objects with multiple neck optical geometries

Ultra compact stellar models with a two-zone uniform density equation of state are considered. They are shown to provide neat examples of optical geometries exhibiting double necks, implying that the gravitational wave potential has a double well structure.

gr-qc↗