Nonthermal Emission Associated with Strong AGN Outbursts at the Centers of Galaxy Clusters

Recently, strong AGN outbursts at the centers of galaxy clusters have been found. Using a simple model, we study particle acceleration around a shock excited by an outburst and estimate nonthermal emission from the accelerated particles. We show that emission from secondary electrons is consistent with the radio observations of the minihalo in the Perseus cluster, if there was a strong AGN outburst >~10^8 yrs ago with an energy of ~1.8x10^62 erg. The validity of our model depends on the frequency of the large outbursts. We also estimate gamma-ray emission from the accelerated particles and show that it could be detected with GLAST.Comment: Accepted for publication in ApJ

Black hole formation and slow-roll inflation

Black hole formation may occur if the spectrum of the curvature perturbation \zeta increases strongly as the scale decreases. As no such increase is observed on cosmological scales, black hole formation requires strongly positive running n' of the spectral index n, though the running might only kick in below the `cosmological scales' probed by the CMB anisotropy and galaxy surveys. A concrete and well-motivated way of producing this running is through the running mass model of slow roll inflation. We obtain a new observational bound n' < 0.026 on the running provided by this model, improving an earlier result by a factor two. We also discuss black hole production in more general scenarios. We show that the usual conditions \epsilon << 1 and |\eta| << 1 are enough to derive the spectrum {\cal P}_{\zeta}(k), the introduction of higher order parameters \xi^{2} etc. being optional.Comment: 11 pages, 6 figures, version to apper in JCA

Big Bang Nucleosynthesis with Long Lived Charged Massive Particles

We consider Big Bang Nucleosynthesis (BBN) with long lived charged massive particles. Before decaying, the long lived charged particle recombines with a light element to form a bound state like a hydrogen atom. This effect modifies the nuclear reaction rates during the BBN epoch through the modifications of the Coulomb field and the kinematics of the captured light elements, which can change the light element abundances. It is possible that the heavier nuclei abundances such as $^7$Li and $^7$Be decrease sizably, while the ratios $Y_p$, D/H, and $^3$He/H remain unchanged. This may solve the current discrepancy between the BBN prediction and the observed abundance of $^7$Li. If future collider experiments found signals of a long-lived charged particle inside the detector, the information of its lifetime and decay properties could provide insights to understand not only the particle physics models but also the phenomena in the early universe in turn.Comment: 20 pages, 6 figures, published version in Physical Review

Development of portable NMR polarimeter system for polarized HD target

A portable NMR polarimeter system has been developed to measure the polarization of a polarized Hydrogen-Deuteride (HD) target for hadron photoproduction experiments at SPring-8. The polarized HD target is produced at the Research Center for Nuclear Physics (RCNP), Osaka university and is transported to SPring-8. The HD polarization should be monitored at both places. We have constructed the portable NMR polarimeter system by replacing the devices in the conventional system with the software system with PCI eXtensions for Instrumentation (PXI). The weight of the NMR system is downsized from 80 kg to 7 kg, and the cost is reduced to 25%. We check the performance of the portable NMR polarimeter system. The signal-to-noise (S/N) ratio of the NMR signal for the portable system is about 50% of that for the conventional NMR system. This performance of the portable NMR system is proved to be compatible with the conventional NMR system for the polarization measurement.Comment: 6 page, 8 figures, 2011/Mar/9 Replace Author

The inflating curvaton

The primordial curvature perturbation \zeta may be generated by some curvaton field \sigma, which is negligible during inflation and has more or less negligible interactions until it decays. In the current scenario, the curvaton starts to oscillate while its energy density \rho_\sigma is negligible. We explore the opposite scenario, in which \rho_\sigma drives a few e-folds of inflation before the oscillation begins. In this scenario for generating \zeta it is exceptionally easy to solve the \eta problem; one just has to make the curvaton a string axion, with anomaly-mediated susy breaking which may soon be tested at the LHC. The observed spectral index n can be obtained with a potential V\propto \phi^p for the first inflation; p=1 or 2 is allowed by the current uncertainty in n but the improvement in accuracy promised by Planck may rule out p=1. The predictions include (i) running n'\simeq 0.0026 (0.0013) for p=1 (2) that will probably be observed, (ii) non-gaussianity parameter f_NL \sim -1 that may be observed, (iii) tensor fraction r is probably too small to ever observed.Comment: 5 pages, 2 figures, revtex, added important results and comment

Formation of primordial black holes from non-Gaussian perturbations produced in a waterfall transition

We consider the process of primordial black hole (PBH) formation originated from primordial curvature perturbations produced during waterfall transition (with tachyonic instability), at the end of hybrid inflation. It is known that in such inflation models, rather large values of curvature perturbation amplitudes can be reached, which can potentially cause a significant PBH production in the early Universe. The probability distributions of density perturbation amplitudes in this case can be strongly non-Gaussian, which requires a special treatment. We calculated PBH abundances and PBH mass spectra for the model, and analyzed their dependence on model parameters. We obtained the constraints on the parameters of the inflationary potential, using the available limits on $\beta_{PBH}$.Comment: v2: 11 pages, 4 figures. Several comments and references added. Version accepted by Phys. Rev.

Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

The Big Bang nucleosynthesis (BBN) in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of Li6 and Li7 are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3x10^2 sec - 10^12 sec. It is stressed that the production of Li6 at early times T ~ 10keV is overestimated by a factor ~ 10 when the approximation of the Saha equation for the He4 bound state fraction is utilised. To obtain conservative limits on the abundance of CHAMPs, a Monte-Carlo analysis with ~ 3x10^6 independent BBN runs, varying reaction rates of nineteen different reactions, is performed (see attached erratum, however). The analysis yields the surprising result that except for small areas in the particle parameter space conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in case a number of heretofore unconsidered reactions may be determined reliably in future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude. An ERRATUM gives limits on primordial CHAMP densities when the by Ref. Kamimura et al. recently more accurately determined CHAMP reaction rates are employed.Comment: includes Erratum showing most up to date limits after determination of the most important reaction rate

Comments on SUSY inflation models on the brane

In this paper we consider a class of inflation models on the brane where the dominant part of the inflaton scalar potential does not depend on the inflaton field value during inflation. In particular, we consider supernatural inflation, its hilltop version, A-term inflation, and supersymmetric (SUSY) D- and F-term hybrid inflation on the brane. We show that the parameter space can be broadened, the inflation scale generally can be lowered, and still possible to have the spectral index $n_s=0.96$.Comment: 7 page