4 research outputs found
On thermal nucleation of quark matter in compact stars
The possibility of a hadron-quark phase transition in extreme astrophysical
phenomena such as the collapse of a supernova is not discarded by the modern
knowledge of the high-energy nuclear and quark-matter equations of state. Both
the density and the temperature attainable in such extreme processes are
possibly high enough to trigger a chiral phase transition. However, the time
scales involved are an important issue. Even if the physical conditions for the
phase transition are favorable (for a system in equilibrium), there may not be
enough time for the dynamical process of phase conversion to be completed. We
analyze the relevant time scales for the phase conversion via thermal
nucleation of bubbles of quark matter and compare them to the typical
astrophysical time scale, in order to verify the feasibility of the scenario of
hadron-quark phase conversion during, for example, the core-collapse of a
supernova.Comment: 6 pages, 4 figures, talk given at the International Conference
SQM2009, Buzios, Rio de Janeiro, Brazil, Sep.27-Oct.2, 200
Nucleation of quark matter in protoneutron star matter
The phase transition from hadronic to quark matter may take place already
during the early post-bounce stage of core collapse supernovae when matter is
still hot and lepton rich. If the phase transition is of first order and
exhibits a barrier, the formation of the new phase occurs via the nucleation of
droplets. We investigate the thermal nucleation of a quark phase in supernova
matter and calculate its rate for a wide range of physical parameters. We show
that the formation of the first droplet of a quark phase might be very fast and
therefore the phase transition to quark matter could play an important role in
the mechanism and dynamics of supernova explosions.Comment: v3: fits version published in Physical Review
Strange quark matter in explosive astrophysical systems
Explosive astrophysical systems, such as supernovae or compact star binary
mergers, provide conditions where strange quark matter can appear. The high
degree of isospin asymmetry and temperatures of several MeV in such systems may
cause a transition to the quark phase already around saturation density.
Observable signals from the appearance of quark matter can be predicted and
studied in astrophysical simulations. As input in such simulations, an equation
of state with an integrated quark matter phase transition for a large
temperature, density and proton fraction range is required. Additionally,
restrictions from heavy ion data and pulsar observation must be considered. In
this work we present such an approach. We implement a quark matter phase
transition in a hadronic equation of state widely used for astrophysical
simulations and discuss its compatibility with heavy ion collisions and pulsar
data. Furthermore, we review the recently studied implications of the QCD phase
transition during the early post-bounce evolution of core-collapse supernovae
and introduce the effects from strong interactions to increase the maximum mass
of hybrid stars. In the MIT bag model, together with the strange quark mass and
the bag constant, the strong coupling constant provides a parameter
to set the beginning and extension of the quark phase and with this the mass
and radius of hybrid stars.Comment: 6 pages, 5 figures, talk given at the International Conference on
Strangeness in Quark Matter (SQM2009), Buzios, Brasil, September 28 - October
2, 2009, to be published in Journal Phys.
Strangeness in Astrophysics and Cosmology
Some recent developments concerning the role of strange quark matter for
astrophysical systems and the QCD phase transition in the early universe are
addressed. Causality constraints of the soft nuclear equation of state as
extracted from subthreshold kaon production in heavy-ion collisions are used to
derive an upper mass limit for compact stars. The interplay between the
viscosity of strange quark matter and the gravitational wave emission from
rotation-powered pulsars are outlined. The flux of strange quark matter nuggets
in cosmic rays is put in perspective with a detailed numerical investigation of
the merger of two strange stars. Finally, we discuss a novel scenario for the
QCD phase transition in the early universe, which allows for a small
inflationary period due to a pronounced first order phase transition at large
baryochemical potential.Comment: 8 pages, invited talk given at the International Conference on
Strangeness in Quark Matter (SQM2009), Buzios, Brasil, September 28 - October
2, 200