Fig. 2: Effects of magnetization on eigenfrequencies of oscillation modes.
From: Oscillations of highly magnetized non-rotating neutron stars
Eigenfrequencies feig of the excited oscillation modes are plotted against the magnetic to binding energy ratio \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\) of the NS model, if \({{{{{\mathcal{l}}}}}}\) = 0 (a), \({{{{{\mathcal{l}}}}}}\) = 2 (b), and \({{{{{\mathcal{l}}}}}}\) = 4 (c) perturbations are applied respectively. The FWHMs in the parabolic interpolations of FFT peaks are taken as the error bars for feig. For all the modes, the data points at H/W ~ 0 (corresponding to REF-T1K5 models) show a nearly horizontal trend, even though these models span a few orders of magnitude in \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\) and can achieve a maximum field strength of 1015−17 G. This implies magnetization has negligible effects on stellar oscillations for NSs with \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\lesssim 1{0}^{-2}\). However, feig noticeably decreases with \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\) for \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\gtrsim 1{0}^{-1}\) in general, and as explained in the caption of Table 1, the expected higher-order hexadecapole (\({{{{{\mathcal{l}}}}}}\) = 4) modes are suppressed or even disappear in the most magnetized models under \({{{{{\mathcal{l}}}}}}\) = 4 perturbation. Hence, we can see that stellar oscillations are significantly suppressed by stronger magnetization for NSs with \({{{{{{{\mathscr{H}}}}}}}}/{{{{{{{\mathscr{W}}}}}}}}\gtrsim 1{0}^{-1}\).
