MG14 - Talk detail

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It has been pointed out the X-ray afterglows from long-duration GRBs are associated with energetic Type Ic supernovae and that they obey a universal scaling law. That is, the late time behavior of the afterglow from all GRBs follows the same universal normalization and power-law behavior at late times when plotted relative to the time of the initial GRB trigger. In this paper we describe constraints from this afterglow on the engine and surrounding medium for GRBs in the context of a model for X-ray emission from accelerated relativistic electrons within an outgoing relativistic shock. We show that such a universal scaling imposes 3 constraints: 1) The shock breakout energy is nearly the same for all bursts independently of when the shock becomes transparent and arrive at the power-law regime; 2) After breakout, the shock propagates through an optically thin low-density medium; and 3) The shock radiates adiabatically. We propose that these facts suggest that the late-time power-law afterglow emission derives from the underlying energetic supernova with a similar total shock energy. We also analyze the observed plateau region in the context of a model simple for the breakout of the supernova material shock heated by the GRB. We argue that the luminosity of the plateau suggests that:1) Dimmer GRBs correspond to the transport of the GRB shock through more material during breakout; and 2) All GRBs energize the outgoing shock to the same energy. We suggest that these points are most consistent with a GRB engine occurring at different radii within the expanding SN shell as in the induced gravitational collapse paradigm.

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We have explored the impact of sterile neutrino dark matter on core-collapse supernova explosions. We have included oscillations between electron neutrinos or mixed neutrinos and right-handed sterile neutrinos into a supernova model. We have chosen sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. Using these simulations, we have explored the impact of sterile neutrinos on the core bounce and shock reheating. We find that, for ranges of sterile neutrino mass and mixing angle consistent with most dark matter constraints, the shock energy can be significantly enhanced and even a model that does not explode can be made to explode. In addition, we have found that the presence of a sterile neutrino may lear to detectable changes in the observed neutrino luminosities.

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The power spectrum of the cosmic microwave background from both the Planck}and WMAP data exhibits a slight dip in for multipoles in the range of l= 10-30. We show that such a dip could be the result of resonant creation of a massive particle that couples to the inflaton field. For our best-fit models, epochs of resonant particle creation reenters the horizon at wave numbers of k~ 0.00011 h/Mpc. The amplitude and location of these features correspond to the creation of a number of degenerate fermion species of mass >15 mpl during inflation depending upon he coupling constant between the inflaton field and the created fermion species. Although the evidence is marginal, if this interpretation is correct, this could an observational hint of new physics beyond the Planck scale.

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