Modern Physics Letters A

The multi-wavelength observations of the 2004 December 27 Giant Flare (GF) from SGR 1806–20 and its long-lived radio afterglow are briefly reviewed. The GF appears to have been produced by a dramatic reconfiguration of the magnetic field near the surface of the neutron star, possibly accompanied by fractures in the crust. The explosive release of over 10⁴⁶ erg (isotropic equivalent) powered a one-sided mildly relativistic outflow. The outflow produced a new expanding radio nebula that is still visible over a year after the GF. Also considered are the constraints on the total energy in the GF, the energy and mass in the outflow, and on the external density, as well as possible implications for short γ-ray bursts and potential signatures in high energy neutrinos, photons, or cosmic rays. Some possible future observations of this and other GFs are briefly discussed.

The complicated processes in medium (decays, reactions and transitions) involving final state absorption are considered. The calculations in the framework of field-theoretical and phenomenological approaches are compared. The reasons for disagreement are studied. The field-theoretical approach can tend to increase the total process probability as well as probability of channel corresponding to absorption, in comparison with phenomenological model.

We use the Riess et al. (2004)¹ supernova Ia apparent magnitude versus redshift data and the Allen et al. (2004)² galaxy cluster gas mass fraction versus redshift data to constrain dark energy models. These data provide complementary constraints that when combined together significantly restrict model parameters and favor slowly-evolving dark energy density models, close to the Einstein cosmological constant limit of dark energy.

We elaborate on the Macfarlane–Biedenharn q-oscillator when q>1. In this case the position operator Q = a^†+a and the momentum operator P = i(a^†-a) are symmetric, but not self-adjoint. For this reason, one cannot specify spectra of Q and P. Since these operators have one-parameter families of self-adjoint extensions with different spectra, the common definition of such q-oscillator is not complete. We derive an action of Q and P (as well as of the related Hamiltonian) upon functions given on the corresponding coordinate spaces, on which Q and P are self-adjoint operators. To each self-adjoint extension of Q there corresponds an appropriate coordinate space (a spectrum of this self-adjoint extension). Thus, for every fixed q>1 one obtains a one-parameter family of non-equivalent q-oscillators in their coordinate spaces.

In this paper, a simultaneous analysis of the elastic scattering data of the ¹⁶O+¹⁶O system for the energy range 5–10 MeV/nucleon is performed theoretically within the framework of the optical model formalism, by using the α–α double folding cluster potential. The α–α double folding cluster potential is evaluated by using the α-cluster distribution densities in the usual nucleon–nucleon double folding process with an effective α–α interaction potential. The results of the α–α double folding cluster potential analysis are compared with the findings of the phenomenological Woods–Saxon squared and nucleon–nucleon double folding potentials. All potentials have exhibited a very good agreement with the experimental measurements for the elastic scattering angular distributions. Furthermore, it is shown that, the α–α double folding cluster potential and nucleon–nucleon double folding potential calculations provide very consistent results with each other. Thus, the ¹⁶O+¹⁶O system has been described by optical potentials having a deep real potential part and a weak absorptive imaginary potential part.

In this paper, we try to detect the SZ effect in the 2MASS DWT clusters and less bound objects in order to constrain the warm-hot intergalactic medium distribution on large scales by cross-correlation analysis. The results of both observed WMAP and mock SZ effect map indicate that the hot gas distributes from inside as well as outside of the high density regions of galaxy clusters, which is consistent with the results of both observation and hydro simulation. Therefore, the DWT measurement of the cross-correlation would be a powerful tool to probe the missing of baryons in the universe.

We give three different spherically symmetric spacetimes for the coupled gravitational and electromagnetic fields with charged source in the tetrad theory of gravitation. One of these contains an arbitrary function and generates the others. These spacetimes give the Reissner–Nordström metric black hole. We then calculated the energy associated with these spacetimes using the superpotential method. We find that unless the time-space components of the tetrad field go to zero faster than at infinity, one gets different results for the energy.