The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes

By M. Miller, Jonathan M. Miller. 2014

161 citations recorded by the source corpus.

Stellar-mass black holes and neutron stars represent extremes in gravity, density, and magnetic fields. They therefore serve as key objects in the study of multiple frontiers of physics. In addition, their origin (mainly in core-collapse supernovae) and evolution (via accretion or, for neutron stars, magnetic spindown and reconfiguration) touch upon multiple open issues in astrophysics. In this review, we discuss current mass and spin measurements and their reliability for neutron stars and stellar-mass black holes, as well as the overall importance of spins and masses for compact object astrophysics. Current masses are obtained primarily through electromagnetic observations of binaries, although future microlensing observations promise to enhance our understanding substantially. The spins of neutron stars are straightforward to measure for pulsars, but the birth spins of neutron stars are more difficult to determine. In contrast, even the current spins of stellar-mass black holes are challenging to measure. As we discuss, major inroads have been made in black hole spin estimates via analysis of iron lines and continuum emission, with reasonable agreement when both types of estimate are possible for individual objects, and future X-ray polarization measurements may provide additional independent information. We conclude by exploring the exciting prospects for mass and spin measurements from future gravitational wave detections, which are expected to revolutionize our understanding of strong gravity and compact objects.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a7c6c4a119b7baebe67b0925e1a70ef80d53568f

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Citations in the corpus

GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs (2018, background): “In current GW observations, small values of χeff are preferred and χp is unconstrained, while spin measurements in X-ray binaries point to a range of spin magnitudes [246], including high spins.”
MERGING BLACK HOLE BINARIES IN GALACTIC NUCLEI: IMPLICATIONS FOR ADVANCED-LIGO DETECTIONS (2016, background): “Our choice is motivated by observations: typical estimates of stellarmass BH spins suggest high values, χ > 0.5, in many cases (for a review see Miller & Miller 2015).”
Stellar structure models in modified theories of gravity: Lessons and challenges (2019, background): “Unfortunately, simultaneous measurements of mass and radius for the same neutron star, which would allow to place constraints upon the EOS, are hard to achieve [30, 31].”
Hierarchical analysis of gravitational-wave measurements of binary black hole spin–orbit misalignments (2017, background): “However, electromagnetic observations of high mass X-ray binaries containing BHs have hinted that the BHs may be more significantly misaligned (Miller & Miller 2015).”
The spin of the second-born black hole in coalescing binary black holes (2018, background): “Many BHs exist in binary systems with non-degenerate companion stars, for example, X-ray binaries, which makes it possible to obtain the BH’s properties indirectly (McClintock 2006; McClintock et al. 2014; Reynolds 2014; Casares & Jonker 2014; Miller & Miller 2015).”
Most Black Holes Are Born Very Slowly Rotating (2019, result): “1) (Miller & Miller 2015).”
Evolutionary roads leading to low effective spins, high black hole masses, and O1/O2 rates for LIGO/Virgo binary black holes (2017, methodology): “For LMC-1 and Cyg X-1 BH spins from both methods are consistent, while for M33 X-7 BH spin was estimated only through disk continuum (Miller & Miller 2015).”
Are LIGO's Black Holes Made from Smaller Black Holes? (2017, background): “Lacking a strong astrophysical prior on the distribution of BH spins (Miller & Miller 2015), we take some fraction fu of the BHs to be uniformly spinning over the allowed range [0,1], and the remaining (1 − fu) of the BHs to come from the hierarchical merger population.”
Evidence for a maximum mass cut-off in the neutron star mass distribution and constraints on the equation of state (2017, background): “1.5ms (Chakrabarty 2008; Papitto et al. 2014; Miller & Miller 2015; Patruno et al. 2017).”