Figure 6.

Braking index n_ig calculated from spin parameters of each segment between glitches as a function of time since last glitch. Large and small circles denote NICER and RXTE values, respectively, with the latter taken from Tables 1 and 2 of Antonopoulou et al. (2018). Errors in n_ig are 1σ uncertainty. Horizontal dotted lines indicate braking index n = 3, 5, 7, which are expected for pulsar spin-down due to electromagnetic dipole radiation, gravitational-wave emitting ellipticity, and gravitational-wave emitting r-mode oscillation, respectively (see Section 5.2). Short and long-dashed lines indicate exponential decay to n = 3 with best-fit timescale of 26 d and to n = 7 with best-fit timescale of 20 d, respectively.