2022A&A...660A..62T


Query : 2022A&A...660A..62T

2022A&A...660A..62T - Astronomy and Astrophysics, volume 660A, 62-62 (2022/4-1)

Speed of sound in dense matter and two families of compact stars.

TRAVERSI S., CHAR P., PAGLIARA G. and DRAGO A.

Abstract (from CDS):

The existence of massive compact stars (M ≥ 2.1 M) implies that the speed of sound exceeds the conformal limit (cs2=1/3 x the squared speed of light in vacuum) if those stars have an inner and outer crust of ordinary nuclear matter. Here, we show that if the most massive objects are strange quark stars, namely, stars entirely composed of quarks, cs can assume values below the conformal limit even while observational limits on those objects are also satisfied. By using astrophysical data associated with those massive stars derived from electromagnetic and gravitational wave signals, we use a Bayesian analysis framework and by adopting a constant speed of sound equation of state to show that the posterior distribution of cs2 is peaked around 0.3 and the maximum mass of the most probable equation of state is ∼2.13 M. We discuss which new data would require a speed of sound larger than the conformal limit even when considering strange quark stars. In particular, we analyze the possibility that the maximum mass of compact stars is larger than 2.5 M, as it would be if the secondary component of GW190814 would turn out to be a compact star - and not a black hole, as previously assumed. Finally, we discuss how the new data for PSR J0740+6620 obtained by the NICER collaboration compare with our results and find they are in qualitative agreement. We conclude with a brief discussion of other possible interpretations of our analysis.

Abstract Copyright: © ESO 2022

Journal keyword(s): dense matter - equation of state - stars: neutron

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 PSR J0437-47 Psr 04 37 15.7994581776 -47 15 08.544351636           DC 836 0
2 PSR J0740+6620 Psr 07 40 45.799 +66 20 33.60           ~ 174 0
3 GrW 170817 GWE 13 09 48.0850 -23 22 53.343           ~ 1486 0
4 X Ara X-1 LXB 17 06 15.314 -43 02 08.69           ~ 254 1
5 4U 1722-30 LXB 17 27 33.25 -30 48 07.4     12.50     ~ 251 1
6 [PLV2002] CX1 LXB 17 48 52.163 -20 21 32.40           ~ 181 1
7 X Sgr X-4 LXB 18 23 40.57 -30 21 40.6   19.06 18.81     ~ 953 1
8 GRB 190425 GWE ~ ~           ~ 213 0
9 GrW 190814 GWE ~ ~           ~ 209 0

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2022.10.02-02:22:03

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