Neutron Stars in <i>f</i>(<i>R</i>)-Gravity and Its Extension with a Scalar Axion Field

• Main Authors: Artyom Astashenok, Sergey Odintsov
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Particles
• Subjects: neutron stars; modified gravity; axions
• Online Access: https://www.mdpi.com/2571-712X/3/3/36
• ISSN: 2571-712X

We present a brief review of general results about non-rotating neutron stars in simple <inline-formula> <math display="inline"> <semantics> <msup> <mi>R</mi> <mn>2</mn> </msup> </semantics> </math> </inline-formula> gravity and its extension with a scalar axion field. Modified Einstein equations are presented for metrics in isotropical coordinates. The mass–radius relation, mass profile and dependence of mass from central density on various equations of state are given in comparison to general relativity.