Structure of compact stars in R-squared Palatini gravity

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• 作者：Florencia A. Teppa Pannia ; Federico García…
• 关键词：Modified gravity ; Palatini formalism ; Neutron stars ; Equation of state
• 刊名：General Relativity and Gravitation
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：49
• 期：2
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Theoretical, Mathematical and Computational Physics; Classical and Quantum Gravitation, Relativity Theory; Differential Geometry; Astronomy, Astrophysics and Cosmology; Quantum Physics;
• 出版者：Springer US
• ISSN：1572-9532
• 卷排序：49

文摘

We analyse configurations of neutron stars in the so-called R-squared gravity in the Palatini formalism. Using a realistic equation of state we show that the mass–radius configurations are lighter than their counterparts in General Relativity. We also obtain the internal profiles, which run in strong correlation with the derivatives of the equation of state, leading to regions where the mass parameter decreases with the radial coordinate in a counter-intuitive way. In order to analyse such correlation, we introduce a parametrisation of the equation of state given by multiple polytropes, which allows us to explicitly control its derivatives. We show that, even in a limiting case where hard phase transitions in matter are allowed, the internal profile of the mass parameter still presents strange features and the calculated \(\mathrm{mass}-\mathrm{radius}\) configurations also yield neutron stars lighter than those obtained in General Relativity.