We perform 1D calculations of neutrino opacities inside a young strange star assumed to be the result of the conversion process of a normal neutron object. We evaluate the deleptonization and cooling timescales, which happen to be longer than the pro
to-NS analogues, and preliminary address the features of the emerging neutrino signal.
The distribution of masses for neutron stars is analyzed using the Bayesian statistical inference, evaluating the likelihood of proposed gaussian peaks by using fifty-four measured points obtained in a variety of systems. The results strongly suggest
the existence of a bimodal distribution of the masses, with the first peak around $1.37 {M_{odot}}$, and a much wider second peak at $1.73 {M_{odot}}$. The results support earlier views related to the different evolutionary histories of the members for the first two peaks, which produces a natural separation (even if no attempt to label the systems has been made here), and argues against the single-mass scale viewpoint. The bimodal distribution can also accommodate the recent findings of $sim M_{odot}$ masses quite naturally. Finally, we explore the existence of a subgroup around $1.25 {M_{odot}}$, finding weak, if any, evidence for it. This recently claimed low-mass subgroup, possibly related to $O-Mg-Ne$ core collapse events, has a monotonically decreasing likelihood and does not stand out clearly from the rest of the sample.
Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-indu
ced breaking of the spatial rotational symmetry, the equation of state (EoS) of the MCFL phase is self-consistently determined. This result is then used to investigate the possibility of absolute stability, which turns out to require a field-dependent bag constant to hold. That is, only if the bag constant varies with the magnetic field, there exists a window in the magnetic field vs. bag constant plane for absolute stability of strange matter. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are calculated and discussed.
Anomalous X-ray Pulsars and Soft-Gamma Repeaters groups are magnetar candidates featuring low characteristic ages ($tau = {Pover{2 {dot P}}}$). At least some of them they should still be associated with the remnants of the explosive events in which t
hey were born, giving clues to the type of events leading to their birth and the physics behind the apparent high value of the magnetar magnetic fields. To explain the high values of $B$, a self-consistent picture of field growth also suggests that energy injection into the SNR is large and unavoidable, in contrast with the evolution of {it conventional} SNR. This modified dynamics, in turn, has important implications for the proposed associations. We show that this scenario yields low ages for the new candidates CXOU J171405.7-381031/CTB 37B and XMMU J173203.3-344518/G353.6-0.7, and predicted values agree with recently found ${dot P}$, giving support to the overall picture.
Several works in the last few years devoted to measure fundamental probes of contemporary cosmology have suggested the existence of a delocalized dominant component (the dark energy), in addition to the several-decade-old evidence for dark matter oth
er than ordinary baryons, both assuming the description of gravity to be correct. Either we are faced to accept the ignorance of at least 95 % of the content of the universe or consider a deep change of the conceptual framework to understand the data. Thus, the situation seems to be completely favorable for a Kuhnian paradigm shift in either particle physics or cosmology. We attempt to offer here a brief discussion of these issues from this particular perspective, arguing that the situation qualifies as a textbook Kuhnian anomaly, and offer a tentative identification of some of the actual elements typically associated with the paradigm shift process in the works in contemporary science.
The accretion of a phantom fluid with non-zero chemical potential by black holes is discussed with basis on the Generalized Second Law of thermodynamics. For phantom fluids with positive temperature and negative chemical potential we demonstrate that
the accretion process is possible, and that the condition guaranteeing the positiveness of the phantom fluid entropy coincides with the one required by Generalized Second Law. In particular, this result provides a complementary confirmation that cosmological phantom fluids do not need to have negative temperatures.
Primordial Quark Nuggets,remnants of the quark-hadron phase transition, may be hiding most of the baryon number in superdense chunks have been discussed for years always from the theoretical point of view. While they seemed originally fragile at inte
rmediate cosmological temperatures, it became increasingly clear that they may survive due to a variety of effects affecting their evaporation (surface and volume) rates. A search of these objects have never been attempted to elucidate their existence. We discuss in this note how to search directly for cosmological fossil nuggets among the small asteroids approaching the Earth. ``Asteroids with a high visible-to-infrared flux ratio, constant lightcurves and devoid of spectral features are signals of an actual possible nugget nature. A viable search of very definite primordial quark nugget features can be conducted as a spinoff of the ongoing/forthcoming NEAs observation programmes.
In this work we extend previous work on the evolution of a Primordial Black Hole (PBH) to address the presence of a dark energy component with a super-negative equation of state as a background, investigating the competition between the radiation acc
retion, the Hawking evaporation and the phantom accretion, the latter two causing a decrease on black hole mass. It is found that there is an instant during the matter-dominated era after which the radiation accretion becomes negligible compared to the phantom accretion. The Hawking evaporation may become important again depending on a mass threshold. The evaporation of PBHs is quite modified at late times by these effects, but only if the Generalized Second Law of thermodynamics is violated.
The accretion of phantom fields by black holes within a thermodynamic context is addressed. For a fluid violating the dominant energy condition, case of a phantom fluid, the Euler and Gibbs relations permit two different possibilities for the entropy
and temperature: a situation in which the entropy is negative and the temperature is positive or vice-versa. In the former case, if the generalized second law (GSL) is valid, then the accretion process is not allowed whereas in the latter, there is a critical black hole mass below which the accretion process occurs. In a universe dominated by a phantom field, the critical mass drops quite rapidly with the cosmic expansion and black holes are only slightly affected by accretion. All black holes disappear near the big rip, as suggested by previous investigations, if the GSL is violated.
Strangelets coming from the interstellar medium (ISM) are an interesting target to experiments searching for evidence of this hypothetic state of hadronic matter. We entertain the possibility of a {it trapped} strangelet population, quite analogous t
o ordinary nuclei and electron belts. For a population of strangelets to be trapped by the geomagnetic field, these incoming particles would have to fulfill certain conditions, namely having magnetic rigidities above the geomagnetic cutoff and below a certain threshold for adiabatic motion to hold. We show in this work that, for fully ionized strangelets, there is a narrow window for stable trapping. An estimate of the stationary population is presented and the dominant loss mechanisms discussed. It is shown that the population would be substantially enhanced with respect to the ISM flux (up to two orders of magnitude) due to quasi-stable trapping.
