Speaker
Description
Since the derivation of a well-defined $D\rightarrow 4$ limit for 4 dimensional Einstein Gauss-Bonnet (4DEGB) gravity coupled to a scalar field, there has been considerable interest in testing it as an alternative to Einstein's general theory of relativity. Using the Tolman-Oppenheimer-Volkoff (TOV) equations modified for charge and 4DEGB gravity, we model the stellar structure of neutron stars, strongly interacting quark stars, and charged, non-interacting quark stars. We find that increasing the Gauss-Bonnet coupling constant $\alpha$, the strong interaction parameter $\lambda$, or the charge $Q$ all tend to increase the mass-radius profiles of quark stars described by this theory, allowing a given central pressure to support larger quark stars in general. These solutions sets are consistent with recent astrophysical data that has been difficult to describe with standard general relativity (GR) and typical neutron star equations of state. We also discuss the lack of a mass gap in 4DEGB gravity derive a generalization of the Buchdahl bound for charged stars in the theory. In all cases, we find that quark stars can exist below the general relativistic Buchdahl bound (BB) and Schwarzschild radius $R=2M$, due to the lack of a mass gap between black holes and compact stars in the 4DEGB theory. Even for $\alpha$ well within current observational constraints, we find that compact star solutions in this theory can also describe Extreme Compact Charged Objects (ECCOs), objects whose radii are smaller than what is allowed by general relativity.
| Keyword-1 | Compact stars |
|---|---|
| Keyword-2 | Modified gravity |
| Keyword-3 | Einstein-Gauss-Bonnet |