ISOLATED NEUTRON STARS
with clearly observed thermal emission in quiescence



Artistic impression © A. Manzoni



The following sample includes all isolated neutron stars for which the emission in quiescence clearly show a thermal component.
Magnetars which show thermal components only during outburst, or have not been detected in quiescence are excluded.
This sample (in its February 2013 version) has been used to compare with magneto-thermal evolutionary models in
Viganò et al. 2013,
where more details about selection of sources, observations and spectral analysis are given.


Source Assoc. Class P dP/dt log(dErot/dt) Bp τc log(τk) log(fabs0.1-10) log(funabs0.1-10) d log(L) kTbb Rbb kTnsa/rcs Rnsa best fit kTcool
[s] [erg/s] [G] [yr] [yr] [erg/cm2s] [erg/cm2s] [kpc] [erg/s] [eV] [km] [eV] [km] model [eV]
CXOU J185238.6+004020 SNR Kes79 CCO 0.105 8.7e-18 32.5 6.1e+10 1.9e+08 3.7-3.9 -12.5 -12.2 7.1 33.5-33.7 440 0.9 220 3.9 BB/nsa < 100
1E 1207.4-5209 SNR G296.5+10.0 CCO 0.424 2.2e-17 31.1 2.0e+11 3.1e+08 3.4-4.3 -11.7 -11.4 2.1 +1.8-0.8 33.0-34.0 190 9.6 110 9.7 BB*/nsa* < 60
RX J0822-4300 SNR PuppisA CCO 0.112 9.3e-18 32.4 6.5e+10 1.9e+08 3.5-3.6 -11.4 -11.1 2.2±0.3 33.5-33.7 400 1.7 155 8.4 BB/nsa < 90
CXO J232327.9+584842 SNR CasA CCO - - - - - 2.5 -12.1 -11.7 3.4 +0.3-0.1 33.4-33.6 450 1.7 219 3.6 BB/nsa < 110
PSR J0538+2817 SNR S147 RPP 0.143 3.7e-15 34.7 1.5e+12 6.2e+05 4.6 -12.0 -11.5 1.3±0.2 32.7-32.9 160 2.6 - - BB+PL < 50
PSR B1055-52 RPP 0.197 5.8e-15 34.5 2.2e+12 5.4e+05 - -11.6 -11.4 0.73±0.15 32.2-32.6 190 0.3 - - 2BB+PL 70
PSR J0633+1746 aka Geminga RPP 0.237 1.1e-14 34.5 3.3e+12 3.4e+05 - -11.8 -11.1 0.25 +0.22-0.08 31.6-32.5 140 0.1 - - 2BB+PL 42
PSR B1706-44 RPP 0.102 9.3e-14 36.5 6.2e+12 1.7e+04 - -12.1 -11.6 2.6 +0.5-0.6 31.7-32.1 160 3.3 - - BB+PL < 60
PSR B0833-45 SNR Vela RPP 0.089 1.2e-13 36.8 6.8e+12 1.1e+04 3.7-4.2 -10.3 -10.2 0.28±0.02 32.1-32.3 120 5.0 61 12.4 (BB/nsa)+PL < 40
PSR B0656+14 SNR Monogem RPP 0.385 5.5e-14 34.6 9.3e+12 1.1e+05 4.9 -10.9 -10.7 0.28±0.03 32.7-32.8 100 2.4 - - 2BB+PL 50
PSR B2334+61 SNR G114.3+0.3 RPP 0.495 1.9e-13 34.8 2.0e+13 4.1e+04 4.0 -12.5 -11.8 3.1 +0.2-2.4 30.7-32.1 160 1.1 65 10.4 BB/nsa < 50
PSR J1740+1000 RPP 0.154 2.1e-12 37.4 3.7e+13 1.1e+03 - -12.9 -12.3 1.4 32.1-32.2 170 0.4 52 10.3 2BB/nsa 78
PSR J0726-2612 HB 3.440 2.9e-13 32.4 6.4e+13 1.9e+05 - -12.2 -12.2 1.0 32.1-32.5 90 4.6 - - BB < 40
PSR J1119-6127 SNR G292.2-0.5 HB 0.408 4.0e-12 36.4 8.2e+13 1.6e+03 3.6-3.9 -13.7 -12.7 8.4±0.4 33.1-33.4 270 1.5 - - BB < 120
PSR J1819-1458 RRAT HB 4.263 5.7e-13 32.5 1.0e+14 1.2e+05 - -12.8 -11.1 3.6 33.6-33.9 130 12.3 - - BB -
PSR J1718-3718 HB 3.378 1.6e-12 33.2 1.5e+14 3.3e+04 - -14.0 -12.6 4.5 +5.5-0.0 32.8-33.5 190 2.0 - - BB < 90
RX J0420.0-5022 XINS 3.450 2.8e-14 31.4 2.0e+13 2.0e+06 - -12.3 -12.2 0.34 30.9-31.0 50 3.4 - - BB* -
RX J1856.5-3754 XINS 7.055 3.0e-14 30.5 2.9e+13 3.8e+06 5.5-5.7 -10.7 -10.7 0.12±0.01 31.5-31.7 63 4.1 - - BB -
RX J2143.0+0654 aka RBS1774 XINS 9.428 4.1e-14 30.3 4.0e+13 3.6e+06 - -11.6 -11.3 0.43 31.8-31.9 107 2.3 - - BB* -
RX J0720.4-3125 XINS 8.391 6.9e-14 30.7 4.9e+13 1.9e+06 5.8-6.0 -11.0 -10.7 0.29 +0.03-0.02 32.2-32.4 84 5.7 - - BB* -
RX J0806.4-4123 XINS 11.370 5.5e-14 30.2 5.1e+13 3.3e+06 - -11.6 -11.6 0.25 31.2-31.4 101 1.2 41 10.8 BB*/nsa* -
RX J1308.6+2127 aka RBS1223 XINS 10.310 1.1e-13 30.6 6.8e+13 1.5e+06 5.9-6.1 -11.5 -11.1 0.50 32.1-32.2 94 5.0 - - BB* -
RX J1605.3+3249 XINS 3.390 1.6e-12 33.2 1.5e+14 3.4e+04 5.7-6.7 -11.1 -11.1 0.35±0.05 31.9-32.2 99 0.9 42 7.0 BB*/nsa* -
1E 2259+586 SNR CTB109 MAG 6.979 4.8e-13 31.7 1.2e+14 2.3e+05 4.0-4.3 -10.6 -8.5 3.2±0.2 35.0-35.4 400 2.9 120 - RCS+PL < 120
4U 0142+614 MAG 8.689 2.0e-12 32.1 2.7e+14 6.9e+04 - -9.9 -8.0 3.6±0.5 35.4-35.8 400 6.5 290 - RCS+PL < 150
CXO J164710.2-455216 cluster Wd1 MAG 10.611 9.7e-13 31.5 2.1e+14 1.7e+05 - -12.6 -10.6 4.0 +1.5-1.0 33.1-33.6 330 0.6 150 - RCS < 120
XTE J1810-197 MAG 5.540 7.8e-12 33.3 4.2e+14 1.1e+04 - -12.1 -10.2 3.6±0.5 34.0-34.4 260 1.9 - - 2BB 116
1E 1547.0-5408 SNR G327.24-0.13 MAG 2.072 4.7e-11 35.3 6.3e+14 7.0e+02 - -12.4 -9.3 4.5±0.5 34.3-34.7 520 0.3 100 - RCS < 150
1E 1048.1-5937 MAG 6.458 2.2e-11 33.5 7.7e+14 4.5e+03 - -10.9 -9.6 2.7±1.0 33.8-34.5 640 0.6 370 - RCS < 100
CXOU J010043.1-721 SMC MAG 8.020 1.9e-11 33.2 7.9e+14 6.8e+03 - -12.3 -12.2 60.6±3.8 35.2-35.5 350 9.2 300 - RCS -
1RXS J170849.0-400910 MAG 11.003 1.9e-11 32.7 9.3e+14 9.1e+03 - -10.6 -10.5 3.8±0.5 34.8-35.1 450 2.1 320 - RCS+PL < 130
CXOU J171405.7-381031 SNR CTB37B MAG 3.825 6.4e-11 34.6 1.0e+15 9.5e+02 3.7 -11.8 -10.4 13.2±0.2 34.9-35.2 540 1.6 340 - RCS < 180
1E 1841-045 SNR Kes73 MAG 11.782 3.9e-11 33.0 1.4e+15 4.8e+03 2.7-3.0 -10.7 -10.2 9.6 +0.6-1.4 35.2-35.5 480 5.0 270 - RCS+PL < 200
SGR 0501+4516 SNR HB9 MAG 5.762 5.8e-12 33.1 3.7e+14 1.6e+04 4.0 -11.5 -9.2 1.5 +1.0-0.5 33.2-34.0 570 0.2 110 - RCS < 100
SGR 1627-41 SNR G337.0-0.1 MAG 2.595 1.9e-11 34.6 4.5e+14 2.2e+03 3.7 -12.5 -11.7 11.0±0.2 34.4-34.8 450 2.0 280 - RCS+PL < 300
SGR 0526-66 SNR N49(LMC) MAG 8.054 3.8e-11 33.5 1.1e+15 3.4e+03 3.7 -12.0 -11.5 49.7±1.5 35.4-35.8 480 3.6 320 - RCS < 200
SGR 1900+14 cluster MAG 5.200 9.2e-11 34.4 1.4e+15 9.0e+02 3.6-3.9 -11.4 -10.6 12.5±1.7 35.0-35.4 390 4.4 330 - RCS+PL < 150
SGR 1806-20 cluster W31 MAG 7.602 2.7e-10 34.4 2.9e+15 4.4e+02 2.8-3.0 -10.9 -10.5 13.0 +4.0-3.0 35.1-35.5 690 2.0 390 - RCS+PL < 250
SGR 0418+5729 MAG 9.078 4.0e-15 29.3 1.2e+13 3.6e+07 - -13.9 -13.8 2.0 30.7-31.1 320 0.1 - - BB < 40
Swift J1822.3-1606 MAG 8.438 8.3e-14 30.7 5.4e+13 1.6e+06 - -11.5 -10.6 1.6±0.3 32.9-33.2 540 0.2 300 - RCS < 70


  • The listed values of Bp correspond to the surface, dipolar strength at the pole. It is estimated assuming that rotational energy losses are caused by the magneto-dipolar radiation in vacuum, Bp = 6.4×1019(P[s] dP/dt)1/2, where we have assumed a star with R = 10 km and moment of inertia I = 1045 g cm-2.
  • The values of the rotational energy loss are obtained by dErot/dt = 3.9×1046(dP/dt)/P[s]3 erg/s, again assuming I = 1045 g cm-2.
  • The reported timing properties are from literature. For details, see references, and, in particular, the ATNF pulsar catalog (Manchester et al. 2005) and the McGill magnetars catalog (Olausen & Kaspi 2013). The spectral properties from the analysis of the single longest available observation (in quiescence) performed by XMM-Newton/EPIC-pn or Chandra/ACIS. For the spectral fit, we have used XSpec v12, always with phabs model (angr abundances), and on the largest possible soft X-ray energy range (where the S/N was acceptable).
  • We report the best fit model(s), where an asterisk indicates the inclusion in the fit of one or more absorption lines. The reported blackbody temperatures (kTbb) correspond to the the best fit obtained either with 1 or 2 BB, plus a power law, if needed. If the best fit is a two blackbody model, the hot component (smaller area) is shown, while the cold component appears in the column kTc, with a radius compatible with the emission from the entire star. For those sources with strong absorption and small Rbb, we provide the upper limits on the hidden (absorbed) temperature of a cold component, defined as the maximum temperature for which, fixing the normalization given by Rns = 10 km and the indicated distance, the χ2 in the thermal fit changes by less than 10%. The luminosity corresponding to this maximum hidden flux is indicated in the last column.
  • The temperatures obtained by fitting to model atmospheres (nsa) are shown only for the less magnetic objects, freezing Mns = 1.4 solar masses, Rns = 10 km and one of the three available magnetic field ( B = 0, 1012, 1013 G), the closest one to the inferred dipolar value. Alternatively, we also give the temperature obtained from the fit to the RCS model. All inferred temperatures are redshifted (i.e., the temperature seen by an observer at infinity).
  • The indicated fluxes are between 0.1 and 10 keV, absorbed and unabsorbed.
  • Luminosities are meant to indicate the integrated bolometric flux radiated from the surface. They are obtained as unabsorbed flux of the thermal component(s) (BB or nsa), or RCS flux in case of magnetars, excluding always the flux associated to the power law component. Errors on luminosities include both the distance uncertainty (indicated as well), the statistical errors, and a minimum arbitrary error of 30% accounting for the model-dependence.


  • Website created, mantained and updated by Daniele Viganò, Nanda Rea, Jose A. Pons, Deborah N. Aguilera and Dany Page

    For questions, comments and corrections please contact:    vigano (at) ice.cat

    Last update: Daniele, 3 November 2014