Trace Anomaly and Effective Topological Sources in Neutron Stars
Abstract
This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six selected after conservative GR stability and speed of sound checks over the tabulated density range. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength ST remained strongly correlated with the topological mass response, with a partial Spearman coefficient ρ= 0.975 within the sampled fiducial sequences. Near 1.4 M⊙, the topological configurations were systematically more compact, with reductions in the Jordan frame radius of $6.7−−8.7\%$ at fixed baryonic mass and $0.87−−1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the Neutron Star Interior Composition Explorer (NICER) and their observational impact depends on the source. Despite the global deformation, the interior effective source remained dominated by matter, with a median topological contribution of about 0.8%. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.
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BibTeX
@misc{nola2026trace,
title = {{Trace Anomaly and Effective Topological Sources in Neutron Stars}},
author = {Federico Nola},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.20460},
eprint = {2608.20460},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.20460},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Trace Anomaly and Effective Topological Sources in Neutron Stars
AU - Federico Nola
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2608.20460
UR - https://arxiv.org/abs/2608.20460
AB - This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six selected after conservative GR stability and speed of sound checks over the tabulated density range. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength S_T remained strongly correlated with the topological mass response, with a partial Spearman coefficient ρ= 0.975 within the sampled fiducial sequences. Near 1.4 M_⊙, the topological configurations were systematically more compact, with reductions in the Jordan frame radius of $6.7−−8.7\%$ at fixed baryonic mass and $0.87−−1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the Neutron Star Interior Composition Explorer (NICER) and their observational impact depends on the source. Despite the global deformation, the interior effective source remained dominated by matter, with a median topological contribution of about 0.8%. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.
ER -