Fig. 3: NS–BH mergers formation probability.
From: Dissecting the properties of neutron star–black hole mergers originating in dense star clusters
a Probability for NS–BH mergers for different configurations. The plot shows the fraction of models producing a NS–BH merger as a function of the cluster velocity dispersion σ in kilometers per second. Interactions between a BH–star binary and a single neutron star (BHSTNS) are marked with circles, whereas the viceversa (NSSTBH) are marked with squares. Open symbols refer to a metallicity value Z = 0.01 Z☉ (being Z☉ the typical solar value), whereas filled symbols refer to Z = 0.01 Z☉. b Merger rate per single cluster. Number of mergers per Gyr and per single cluster as a function of the cluster velocity dispersion. Symbols and colors are the same as in a. Dotted lines represent best-fit power-law functions. The ratio between the Chi-square and the number of degrees of freedom is χ2/NDF < 2.6 for NSSTBH and <0.5 for BHSTNS, assuming a 10% error associated to the measure of the scattering rate and the measure of the merging probability.
