Figure 1

$T_{\mathrm{eff}}$ vs $B_d$ of isolated NSs. Represented with different symbols are soft-gamma repeaters (stars), anomalous x-ray pulsars (diamonds), slowly rotating ($P>3\mathrm{s}$) NSs (squares), and rapidly rotating ($P<0.5\mathrm{s}$) NSs (triangles). Red symbols (stars and open triangles and diamonds) correspond to young ($<{10}^4\mathrm{yr}$) NSs. Symbols with arrows indicate upper limits. The blue symbols (open squares) are isolated NSs for which the magnetic field was estimated from the association of a spectral feature with a proton cyclotron resonance. We show how two of these (RX J0720.4–3125 and RBS1223) move to the left if their fields inferred from cyclotron lines are replaced by $B_d$. The solid line is an illustration of heating balanced by cooling, for $b=100$ [see Eq. (3)].Reuse & Permissions