Axial Perturbations of Extended Tolman III in the New f(R,T) Theory

@misc{jayawiguna2026axial,
  title = {{Axial Perturbations of Extended Tolman III in the New $f(R,T)$ Theory}},
  author = {B. N. Jayawiguna and G. A. Sabian and H. S. Ramadhan and A. Sulaksono},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.30770},
  eprint = {2610.30770},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.30770},
}

TY  - UNPB
TI  - Axial Perturbations of Extended Tolman III in the New f(R,T) Theory
AU  - B. N. Jayawiguna
AU  - G. A. Sabian
AU  - H. S. Ramadhan
AU  - A. Sulaksono
PY  - 2026
DA  - 2026/10/22
PB  - arXiv
DO  - 10.48550/arxiv.2610.30770
UR  - https://arxiv.org/abs/2610.30770
AB  - We investigate compact objects using the extended Tolman III equation of state in the framework of f(R,T)=R+2χT gravity. In the matter sector of the Lagrangian density, we employ a new formalism based on the evaluation of the second-order derivative of the matter Lagrangian with respect to the metric \cite{Jayawiguna:2026das}. We analyze the corresponding observational signatures through axial gravitational perturbations including stellar stability and gravitational echo. We find that the effective potential in f(R,T) gravity is wider and deeper than its counterpart in general relativity (GR). The quasinormal-mode (QNM) frequencies are calculated using the Bohr--Sommerfeld (BS) fitting and both the lower- and higher-order Wentzel--Kramers--Brillouin (WKB) approximations. For the ultracompact configurations considered, trapped modes can tunnel through the potential barrier, giving rise to gravitational-wave echoes. The imaginary parts of the QNM frequencies are found to be negative, ℑ(ω_n M)<0, indicating that the perturbations decay exponentially with time. Our results show that the echo train in GR contains more echoes than that in f(R,T) gravity. Finally, assuming that the stellar object is a neutron star and adopting a stellar radius consistent with measurements by the Neutron Star Interior Composition Explorer (NICER), we find that the f(R,T) gravity model yields a characteristic frequency consistent with the estimated frequency associated with GW170817 for β= 4.663×10^−1 and χ=0.96π, whereas the corresponding GR model does not exhibit comparable agreement.
ER  -