Abstract
We studied herein the mass and the radius of brown dwarfs predicted by beyond Horndeski (BH) and Eddington-inspired Born-Infeld (EiBI) gravity theories by numerically solving the modified non-relativistic hydrostatic equations of both theories. We used a recent compilation of brown dwarf masses and radii obtained from Ref. Bayliss et al. (Astrophys J 153:1, 2016) to constrain the free parameter of both theories. We obtain the range of the corresponding parameters with 1sigma and 5sigma confidence by using chi-squared analysis. Furthermore, the minimum chi-squared values can be reached for the cases of kappa = 0.17 times 10^2 ~mathrm{m}^5,mathrm{kg}^{-1},mathrm{s}^{-2} and gamma = -0.1207 for EiBI and BH theories, respectively. The corresponding parameter values with the minimum chi-squared values are relatively small; therefore, they cannot significantly change the brown dwarf mass limits determined from the equivalence of nuclear and photosphere luminosities for the pp (hydrogen burning) and pp+pd (deuterium burning) reactions.
Highlights
BDs were theoretically predicted for the first time in 1963 by Kumar [33] and Hayashi and Nakano [34]
The obtained free parameters are used to calculate the mass limits determined from the equivalence of nuclear and photon sphere luminosities for the pp and pp+pd reactions predicted by the Eddington-inspired Born-Infeld (EiBI) and HB theories and compared to the ones of GR
We studied the mass and the radius of BDs as a representation of lesscompact stars predicted by beyond Horndeski (BH) and EiBI gravity theories by numerically solving the modified hydrostatic equations predicted by both theories
Summary
BDs were theoretically predicted for the first time in 1963 by Kumar [33] and Hayashi and Nakano [34]. Note that a recent study on deuterium burning in objects forming through the core accretion scenario has shown that the value of the MMDB (0.013M ) does not change much when none of the corresponding investigated parameters was able to change this mass limit by more than 0.0008M. These studies, used chi-squared analysis to determine the allowed region of parameter space with its corresponding confidence This analysis is very robust determining the acceptable parameter of the modified gravity theories from the observation data of WD properties. The obtained free parameters are used to calculate the mass limits determined from the equivalence of nuclear and photon sphere luminosities for the pp (hydrogen burning) and pp+pd (deuterium burning) reactions predicted by the EiBI and HB theories and compared to the ones of GR.
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