English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The dark matter hypothesis, which is not called into question here, explainswhy typical rotation curves of spiral galaxies do not follow a Keplerianprofile. It is however not sufficient in itself to explain why the whole matterdistribution in spiral galaxies is such that the rotation curve generallypresents a flat profile in the disk region.  To understand this property, a model considering general relativistic effectsis developed. It is stressed that the aim is not to explain the flat rotationcurve of spiral galaxies without dark matter. More specifically, the analyticalstationary solution of an axisymmetric rotating pressureless fluid for thelinearized equations of the theory of general relativity is determined. It isdemonstrated that this solution leads to some constraints on the rotationcurve, by looking to its limit behavior when neglecting general relativisticeffects. In particular, the positiveness of the density imposes the rotationcurve to be flat in the regions where the density and general relativisticeffects are small, such as in the disk region. General relativistic effectshence remain negligible in the disk region, but their consideration proved tobe necessary to establish the aforementioned constraint. Such constraint cannotbe derived from a Newtonian approach.  The model is finally applied on two specific cases to demonstrate its abilityto predict the rotation curve from a typical density profile along the galacticplane. These examples suggest that for some galaxies, general relativisticeffects can be significant close to the bulge region and should be taken intoaccount to have a proper understanding of their rotation curve.

A simplified general relativistic model to analyze the structure of spiral galaxies