scholarly journals Towards New Constraints in Extended Theories of Gravity: Cosmography and Gravitational-Wave Signals from Neutron Stars

Galaxies ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 28
Author(s):  
Álvaro de la Cruz Dombriz
Keyword(s):  
Neutron Stars ◽  
Gravitational Wave ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories

scholarly journals Extreme neutron stars from Extended Theories of Gravity

2015 ◽  
Vol 2015 (01) ◽  
pp. 001-001 ◽  
Author(s):  
Artyom V. Astashenok ◽  
Salvatore Capozziello ◽  
Sergei D. Odintsov
Keyword(s):  
Neutron Stars ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories

Shadow from a rotating black hole in an extended gravity

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040060
Author(s):  
Vjacheslav Prokopov ◽  
Stanislav Alexeyev
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Rotating Black Hole ◽  
Extended Gravity ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories

We focus on the consequences of that the Event Horizon Telescope obtained images of the black hole shadow in the center of the M87 galaxy. We show that to test extended theories of gravity the improving of the resolution by 3 orders is necessary. In addition it is demonstrated that the rotation distorts the shape of the shadow and corrections from the extended gravity may affect on this distortion.

scholarly journals Evaporation/Antievaporation and energy conditions in alternative gravity

2018 ◽  
Vol 33 (04) ◽  
pp. 1850030 ◽  
Author(s):  
Andrea Addazi
Keyword(s):  
General Relativity ◽  
Degrees Of Freedom ◽  
Energy Conditions ◽  
Raychaudhuri Equation ◽  
Bonnet Gravity ◽  
Extended Theories Of Gravity ◽  
Theories Of Gravity ◽  
Extended Theories ◽  
Alternative Gravity

We discuss the evaporation and antievaporation instabilities of Nariai solution in extended theories of gravity. These phenomena were explicitly shown in several different extensions of General Relativity, suggesting that a universal cause is behind them. We show that evaporation and antievaporation are originated from deformations of energy conditions on the Nariai horizon. Energy conditions get new contributions from the extra propagating degrees of freedom, which can provide extra focalizing or antifocalizing terms in the Raychaudhuri equation. We show the two explicit cases of [Formula: see text]-gravity and Gauss–Bonnet gravity.

Sign in / Sign up

Export Citation Format

Share Document