Cyclotron line signatures of thermal and magnetic mountains from accreting neutron stars

摘要: Cyclotron resonance scattering features (CRSFs) in the X-ray spectrum of an accreting neutron star are modified differently by accretion mounds sustained magnetic and thermocompositional gradients. It is shown that one can discriminate, principle, between different physical origins studying how line energy, width, depth a CRSF depend on orientation star, accreted mass, surface temperature distribution, equation state. signatures including gravitational light bending computed for both phase-resolved phase-averaged spectra basis self-consistent Grad-Shafranov mound equilibria satisfying global flux-freezing constraint. The prospects multimessenger gravitational-wave observations with future instruments canvassed briefly.