Large sound speed in dense matter and the deformability of neutron stars
Abstract
The historic first detection of the binary neutron star merger GW170817 by the LIGO-Virgo collaboration has set a limit on the gravitational deformability of neutron stars. In contrast, radio observations of PSR J0740 + 6620 find a very massive neutron star. Tension between the small deformability and the large maximum mass may suggest that the pressure rises rapidly with density and thus the speed of sound in dense matter is likely a large fraction of the speed of light. Herein, we use these observations and simple constant sound-speed model equations of state to set a lower bound on the maximum speed of sound in neutron stars. If the tidal deformability of a 1.4$$_\odot$$ neutron star is less than 600, as is suggested by subsequent analyses of GW170817, we find that the sound speed in the cores of neutron stars is likely larger than the conformal limit of $$c/\sqrt{3}$$. Implications of this for our understanding of both hadronic and quark-gluon descriptions of dense matter are discussed.
- Publication Date:
- Research Org.:
- Indiana Univ., Bloomington, IN (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Nuclear Physics (NP); National Science Foundation (NSF)
- OSTI Identifier:
- 1660440
- Alternate Identifier(s):
- OSTI ID: 1615715
- Grant/Contract Number:
- FG02-87ER40365; PHY-1430152; SC0008808
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physical Review C
- Additional Journal Information:
- Journal Volume: 101; Journal Issue: 4; Journal ID: ISSN 2469-9985
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 79 ASTRONOMY AND ASTROPHYSICS
Citation Formats
Reed, Brendan, and Horowitz, C. J. Large sound speed in dense matter and the deformability of neutron stars. United States: N. p., 2020.
Web. doi:10.1103/physrevc.101.045803.
Reed, Brendan, & Horowitz, C. J. Large sound speed in dense matter and the deformability of neutron stars. United States. https://doi.org/10.1103/physrevc.101.045803
Reed, Brendan, and Horowitz, C. J. Wed .
"Large sound speed in dense matter and the deformability of neutron stars". United States. https://doi.org/10.1103/physrevc.101.045803. https://www.osti.gov/servlets/purl/1660440.
@article{osti_1660440,
title = {Large sound speed in dense matter and the deformability of neutron stars},
author = {Reed, Brendan and Horowitz, C. J.},
abstractNote = {The historic first detection of the binary neutron star merger GW170817 by the LIGO-Virgo collaboration has set a limit on the gravitational deformability of neutron stars. In contrast, radio observations of PSR J0740 + 6620 find a very massive neutron star. Tension between the small deformability and the large maximum mass may suggest that the pressure rises rapidly with density and thus the speed of sound in dense matter is likely a large fraction of the speed of light. Herein, we use these observations and simple constant sound-speed model equations of state to set a lower bound on the maximum speed of sound in neutron stars. If the tidal deformability of a 1.4$_\odot$ neutron star is less than 600, as is suggested by subsequent analyses of GW170817, we find that the sound speed in the cores of neutron stars is likely larger than the conformal limit of $c/\sqrt{3}$. Implications of this for our understanding of both hadronic and quark-gluon descriptions of dense matter are discussed.},
doi = {10.1103/physrevc.101.045803},
journal = {Physical Review C},
number = 4,
volume = 101,
place = {United States},
year = {Wed Apr 22 00:00:00 EDT 2020},
month = {Wed Apr 22 00:00:00 EDT 2020}
}
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