# The neutron star mass-radius relation and the equation of state of dense matter

### Steiner, Lattimer, and Brown (2013)

Figures: Left panel: the equation of state implied by neutron star mass and radius observations, right panel: the most probable mass-radius relation.

Summary:

Using recent neutron star mass and radius observations we determined the neutron star mass-radius curve and the equation of state (EOS). J. Lattimer (Stony Brook), E. Brown (Michigan State) and I chose several different EOS models and analyzed several alternative interpretations of the data to ensure our results were robust. We found that there is significant uncertainty in the EOS just above the saturation density because of potential phase transitions, but found radii between 10.4 and 12.9 km.

Related source-code for this work is also available.

Our results are published in Astrophys. J. Lett. 765 (2013) 5 .

#### EOS table:

Energy density$-2 \sigma$ limit on pressure$-1 \sigma$ limit on pressure $+1 \sigma$ limit on pressure $+2 \sigma$ limit on pressure Percent uncertainty
(MeV/fm3) (MeV/fm3) (MeV/fm3) (MeV/fm3) (MeV/fm3) from $1 \sigma$ limits
2004.3244.663 6.4867.72733
3005.1816.390 22.5029.27112
4007.75910.39 65.5885.86145
50039.6343.86 123.0141.595
60068.9175.23 208.1225.794
700107.6117.7 278.9308.981
800159.7167.9 368.2401.175
900215.5231.8 460.5509.966
1000239.5283.3 554.3594.265
1100265.4322.5 605.4661.961
1200282.3360.6 671.4749.660
1300303.7398.8 747.7843.861
1400321.7436.4 832.5936.162