Solving Tolman-Oppenheimer-Volkoff Equations in f(T) Gravity: a Novel Approach Applied to Polytropic Equations of State

The Teleparallel Theory is an alternative theory of gravity equivalent to general relativity (GR) and with non-vanishing torsion T . Some extensions of this theory, the so-called f ( T ) models, have been subject of many recent works. The purpose of our work in the end is to consider recent results for a specific family of f ( T ) models by using their corresponding Tolman-Oppenheimer-Volkof equation to describe compact objects such as neutron stars. By performing numerical calculations, it is possible to find, among other things, the maximum mass allowed by the model for a neutron star for a given equation of state (EOS), which would also allow us to evaluate which models are in accordance with observations. To begin with, the present work, the second in the series, considers polytropic EOSs since they can offer a simpler and satisfactory description for the compact objects. In addition, with these EOSs, we can already assess how different the f ( T ) theories are in relation to GR with respect to the stellar structure. Moreover, there is only a few studies in f ( T ) regarding polytropic EOSs; therefore, there is space for further studies. The results already known to GR must be reproduced to some extent and, eventually, we can find models that allow higher maximum masses than GR itself, which could explain, for example, the secondary component of the event GW190814. This particular issue is subject of another paper, the third in the series, where realistic EOSs are considered.