Related papers: On the maximum mass limit of neutron stars in scal…
The masses and radii of neutron stars are discussed in general relativity and scalar-tensor theory of gravity and the differences are compared with the current uncertainties stemming from the nuclear equation of state in the relativistic…
At the supranuclear densities achieved inside a neutron star, matter may exhibit extreme properties. In particular, it may be the case that a suitable average of the speed of sound squared exceeds the so-called conformal limit, i.e.,…
It has been suggested in the literature that the sound velocity of the nuclear matter $v_s$ violates the so-called sound velocity bound $v_s \le c/\sqrt{3}$ at high density, where $c$ is the speed of light. In this paper, we revisit this…
In order to systematically examine the possible maximum mass of neutron stars, which is one of the important properties characterizing the physics in high-density region, I construct neutron star models by adopting phenomenological…
The accurate determination of the maximum mass of the neutron stars is one of the most important tasks in astrophysics. It is directly related to the identification of the black holes in the universe, the production of neutron stars from…
The observation of maximally rotating neutron stars (in comparison to nonrotating ones) may provide more information on the behavior of nuclear matter at high densities. We provide a theoretical treatment concerning the effects of the upper…
We systematically examine the compactness of neutron stars as Tolman VII solutions in scalar-tensor theory of gravity. As a result, when the coupling constant is confined to values provided by astronomical observations we show that the…
We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We…
It has been conjectured that the velocity of sound in any medium is smaller than the velocity of light in vacuum divided by $\sqrt{3}$. Simple arguments support this bound in non-relativistic and/or weakly coupled theories. The bound has…
One of the most intringuing questions about neutron stars concerns their maximum mass. The answer is intimately related to the properties of matter at densities far beyond that found in heavy atomic nuclei. The current view on the internal…
We investigate the causal limit of maximum mass for stars in the framework of$f(R)$ gravity. We choose a causal equation of state, with variable speed of sound, and with the transition density and pressure corresponding to the SLy equation…
In order to solve the Tolman-Oppenheimer-Volkoff equations for neutron stars, one routinely uses the equation of states which are computed in the Minkowski spacetime. Using a first-principle approach, it is shown that the equation of states…
We demonstrate that the largest measured mass of a neutron star establishes an upper bound to the energy density of observable cold matter. An equation of state-independent expression satisfied by both normal neutron stars and self-bound…
Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints we construct a novel, scale-independent description of the sound speed in neutron stars where the latter is expressed in…
The maximum mass of a neutron star is generally determined by the equation of state of the star material. In this study, we take into account dark matter particles, assumed to behave like fermions with a free parameter to account for the…
Observational identification of black holes as members of binary systems requires the knowledge of the upper limit on the gravitational mass of a neutron star. We use modern equations of state for neutron star matter, fitted to experimental…
Scalar-tensor~(ST) theories of gravity are natural phenomenological extensions to general relativity. Although these theories are severely constrained both by solar system experiments and by binary pulsar observations, a large set of ST…
Chiral Lagrangian and quark-meson coupling models of hyperon matter are used to estimate the maximum mass of neutron stars. Our relativistic calculations include, for the first time, both Hartree and Fock contributions in a consistent…
The upper bound on the value of the surface gravity, g_s, for neutron stars with equations of state respecting v_sound <= c, is derived. This bound is inversely proportional to the maximum allowable mass M_max, and it reads g_s <= 1.411 x…
We point out that there is an upper bound on the speed of sound squared given by $c_s^2 \leq 0.781$ valid for all known systems described by relativistic transient hydrodynamics where calculations of certain ratios of hydrodynamic transport…