3 research outputs found
Quasi-stationary sequences of hyper massive neutron stars with exotic equations of state
In this work, we study the effect of differential rotation, finite
temperature and strangeness on the quasi stationary sequences of hyper massive
neutron stars (HMNS). We generate constant rest mass sequences of
differentially rotating and uniformly rotating stars. The nucleonic matter
relevant to the star interior is described within the framework of the
relativistic mean field model with the DD2 parameter set. We also consider the
strange hyperons using the BHB equation of state (EoS).
Additionally, we probe the behaviour of neutron stars (NS) with these
compositions at different temperatures. We report that the addition of hyperons
to the EoS produces a significant boost to the spin-up phenomenon. Moreover,
increasing the temperature can make the spin-up more robust. We also study the
impact of strangeness and thermal effects on the T/W instability. Finally, we
analyse equilibrium sequences of a NS following a stable transition from
differential rotation to uniform rotation. The decrease in frequency relative
to angular momentum loss during this transition is significantly smaller for
EoS containing hyperons, compared to nucleonic EoS.Comment: Accepted for publication in the Journal of Astrophysics and Astronom
Characterizing Gravitational Wave Detector Networks: From A to Cosmic Explorer
Gravitational-wave observations by the Laser Interferometer
Gravitational-Wave Observatory (LIGO) and Virgo have provided us a new tool to
explore the universe on all scales from nuclear physics to the cosmos and have
the massive potential to further impact fundamental physics, astrophysics, and
cosmology for decades to come. In this paper we have studied the science
capabilities of a network of LIGO detectors when they reach their best possible
sensitivity, called A#, and a new generation of observatories that are factor
of 10 to 100 times more sensitive (depending on the frequency), in particular a
pair of L-shaped Cosmic Explorer observatories (one 40 km and one 20 km arm
length) in the US and the triangular Einstein Telescope with 10 km arms in
Europe. We use a set of science metrics derived from the top priorities of
several funding agencies to characterize the science capabilities of different
networks. The presence of one or two A# observatories in a network containing
two or one next generation observatories, respectively, will provide good
localization capabilities for facilitating multimessenger astronomy and
precision measurement of the Hubble parameter. A network of two Cosmic Explorer
observatories and the Einstein Telescope is critical for accomplishing all the
identified science metrics including the nuclear equation of state,
cosmological parameters, growth of black holes through cosmic history, and make
new discoveries such as the presence of dark matter within or around neutron
stars and black holes, continuous gravitational waves from rotating neutron
stars, transient signals from supernovae, and the production of stellar-mass
black holes in the early universe. For most metrics the triple network of next
generation terrestrial observatories are a factor 100 better than what can be
accomplished by a network of three A# observatories.Comment: 45 pages, 20 figure
Maximum mass of compact stars from gravitational wave events with finite-temperature equations of state
International audienceWe conjecture and verify a set of relations between global parameters of hot and fast-rotating compact stars which do not depend on the equation of state, including a relation connecting the masses of the mass-shedding (Kepler) and static configurations. We apply these relations to the GW170817 event by adopting the scenario in which a hypermassive compact star remnant formed in a merger evolves into a supramassive compact star that collapses into a black hole once the stability line for such stars is crossed. We deduce an upper limit on the maximum mass of static, cold neutron stars 2.15−0.17+0.18≤MTOV★/M⊙≤2.24−0.44+0.45 for the typical range of entropy per baryon, 2≤S/A≤3, and electron fraction Ye=0.1 characterizing the hot hypermassive star. Our result implies that accounting for the finite temperature of the merger remnant relaxes previously derived constraints on the value of the maximum mass of a cold, static compact star