2,890 research outputs found
Strange quark matter fragmentation in astrophysical events
The conjecture of Bodmer-Witten-Terazawa suggesting a form of quark matter
(Strange Quark Matter) as the ground state of hadronic interactions has been
studied in laboratory and astrophysical contexts by a large number of authors.
If strange stars exist, some violent events involving these compact objects,
such as mergers and even their formation process, might eject some strange
matter into the interstellar medium that could be detected as a trace signal in
the cosmic ray flux. To evaluate this possibility, it is necessary to
understand how this matter in bulk would fragment in the form of strangelets
(small lumps of strange quark matter in which finite effects become important).
We calculate the mass distribution outcome using the statistical
multifragmentation model and point out several caveats affecting it. In
particular, the possibility that strangelets fragmentation will render a tiny
fraction of contamination in the cosmic ray flux is discussed.Comment: 13 pages, 4 figure
Interaction of strangelets with ordinary nuclei
Strangelets (hypothetical stable lumps of strange quarkmatter) of
astrophysical origin may be ultimately detected in specific cosmic ray
experiments. The initial mass distribution resulting from the possible
astrophysical production sites would be subject to reprocessing in the
interstellar medium and in the earth's atmosphere. In order to get a better
understanding of the claims for the detection of this still hypothetic state of
hadronic matter, we present a study of strangelet-nucleus interactions
including several physical processes of interest (abrasion, fusion, fission,
excitation and de-excitation of the strangelets), to address the fate of the
baryon number along the strangelet path. It is shown that, although fusion may
be important for low-energy strangelets in the interstellar medium (thus
increasing the initial baryon number A), in the earth's atmosphere the loss of
the baryon number should be the dominant process. The consequences of these
findings are briefly addressed
Dark Matter, Dark Energy and Modern Cosmology: The Case For a Kuhnian Paradigm Shift
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” other 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 shiftin 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
Einstein observations and the internal dynamics of compact stars: further evidence against non-linear regimes of vortex creep
Structural constraints are presented on the Crab and Vela pulsars imposed by the simultaneous assumptions of (a) surface temperatures close to those observed by the Einstein Observatory satellite, and (b) validity of the vortex creep theory in the nonlinear regime for interpreting glitch observations and internal features predicted by it. The disagreement between both studies is quantified, thus pointing strongly to the need for linear regimes of creep, as recently suggested, or some alternative pictureFacultad de Ciencias Astronómicas y Geofísica
Radial pulsations of strange stars and the internal composition of pulsars
Calculations of radial oscillations of homogeneous strange stars, showing that the particular form of the equation of state allows some simple and general scaling relations which may prove to be very useful for the search of these objects, are presentedFacultad de Ciencias Astronómicas y Geofísica
Nucleosynthesis in Strange Star Mergers
The possible existence of deconfined matter in the cores of neutron stars has been studied for over three decades without a firm indication either for or against this proposition. Analysis mostly rely on the comparison of mass-radius curves obtained for different compositions with observational data on the mass of the most massive objects of this kind accurately determined. Nevertheless, there are other possibilities for indirectly studying the internal composition of this class of compact objects, e.g, analyzing cooling behavior, X-ray bursts, supernova’s neutrinos. We present calculations on the expected nucleosynthesis spectra for the strange star-strange star merger scenario as means to test the strange quark matter hypothesis and its realization inside such objects. This would result very different from the typical r-process nucleosynthesis expected in neutron star mergers since the high temperature deconfinement of strange matter would produce large amounts of neutrons and protons and the mass buildup would proceed in a Big-Bang nucleosynthesis like scenario. The neutron to proton ratio would allow to reach the iron peak only, a very different prediction from the standard scenario. The resultant light curve indicate it may be compatible with that of a kilonova depending on the specific details of the ejecta.Facultad de Ciencias Astronómicas y Geofísica
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