The Fermi Bubbles: Gamma-ray, Microwave, and Polarization Signatures of Leptonic AGN Jets

The origin of the Fermi bubbles and the microwave haze is yet to be determined. To disentangle different models requires detailed comparisons between theoretical predictions and multi-wavelength observations. Our previous simulations have demonstrated that the primary features of the Fermi bubbles could be successfully reproduced by recent jet activity from the central active galactic nucleus (AGN). In this work, we generate gamma-ray and microwave maps and spectra based on the simulated properties of cosmic rays (CRs) and magnetic fields in order to examine whether the observed bubble and haze emission could be explained by leptons contained in the AGN jets. We also investigate the model predictions of the polarization properties of the Fermi bubbles. We find that: (1) The same population of leptons can simultaneously explain the bubble and haze emission given that the magnetic fields within the bubbles are very close to the exponentially distributed ambient field, which can be explained by mixing in of the ambient field followed by turbulent field amplification; (2) The centrally peaked microwave profile suggests CR replenishment, which is consistent with the presence of a more recent second jet event; (3) The bubble interior exhibits a high degree of polarization because of ordered radial magnetic field lines stretched by elongated vortices behind the shocks; highly-polarized signals could also be observed inside the draping layer; (4) Enhancement of rotation measures could exist within the shock-compressed layer because of increased gas density and more amplified and ordered magnetic fields. We discuss the possibility that the deficient haze emission at b<-35 degrees is due to the suppression of magnetic fields, which is consistent with the existence of lower-energy CRs causing the polarized emission at 2.3 GHz. Possible AGN jet composition in the leptonic scenario is also discussed.Comment: 15 pages, 9 figures, matched with MNRAS published versio

Baseline Evaluation of Thin-Film Amorphous Silicon, Copper Indium Diselenide, and Cadmium Telluride for the 21st Century: Preprint

This paper examines three thin-film PV technologies: amorphous silicon, cadmium telluride, and copper indium selenide. The purpose is to: (1) assess their status and potential; (2) provide an improved set of criteria for comparing these existing thin films against any new PV technological alternatives, and examining the longer-term (c. 2050) potential of thin films to meet cost goals that would be competitive with conventional sources of energy without any added value from the substantial environmental advantages of PV. Among the conclusions are: (1) today's thin films have substantial economic potential, (2) any new approach to PV should be examined against the substantial achievements and potential of today's thin films, (3) the science and technology base of today's thin films needs substantial strengthening, (4) some need for alternative technologies exists, especially as the future PV marketplace expands beyond about 30 GW of annual production

1D Modeling for Temperature-Dependent Upflow in the Dimming Region Observed by Hinode/EIS

We have previously found a temperature-dependent upflow in the dimming region following a coronal mass ejection (CME) observed by the {\it Hinode} EUV Imaging Spectrometer (EIS). In this paper, we reanalyzed the observations along with previous work on this event, and provided boundary conditions for modeling. We found that the intensity in the dimming region dramatically drops within 30 minutes from the flare onset, and the dimming region reaches the equilibrium stage after $\sim$1 hour later. The temperature-dependent upflows were observed during the equilibrium stage by EIS. The cross sectional area of the fluxtube in the dimming region does not appear to expand significantly. From the observational constraints, we reconstructed the temperature-dependent upflow by using a new method which considers the mass and momentum conservation law, and demonstrated the height variation of plasma conditions in the dimming region. We found that a super radial expansion of the cross sectional area is required to satisfy the mass conservation and momentum equations. There is a steep temperature and velocity gradient of around 7 Mm from the solar surface. This result may suggest that the strong heating occurred above 7 Mm from the solar surface in the dimming region. We also showed that the ionization equilibrium assumption in the dimming region is violated especially in the higher temperature range.Comment: accepted for publication in The Astrophysical Journa

The acceleration and propagation of solar flare energetic particles

Observations and theories of particle acceleration in solar flares are reviewed. The most direct signatures of particle acceleration in flares are gamma rays, X-rays and radio emissions produced by the energetic particles in the solar atmosphere and energetic particles detected in interplanetary space and in the Earth's atmosphere. The implication of these observations are discussed. Stochastic and shock acceleration as well as acceleration in direct electric fields are considered. Interplanetary particle propagation is discussed and an overview of the highlights of both current and promising future research is presented

Lessons Learned from the Photovoltaic Manufacturing Technology/PV Manufacturing R&D and Thin Film PV Partnership Projects

As the U.S. Department of Energy's (DOE's) Solar Energy Technologies Program initiates new cost-shared solar energy R&amp;D under the Solar America Initiative (SAI), it is useful to analyze the experience gained from cost-shared R&amp;D projects that have been funded through the program to date. This report summarizes lessons learned from two DOE-sponsored photovoltaic (PV) projects: the Photovoltaic Manufacturing Technology/PV Manufacturing R&amp;D (PVMaT/PVMR&amp;D) project and the Thin-Film PV Partnership project. During the past 10-15 years, these two projects have invested roughly 330 million of government resources in cost-shared R&D and leveraged another 190 million in private-sector PV R&amp;D investments. Following a description of key findings and brief descriptions of the PVMaT/PVMR&amp;D and Thin-Film PV Partnership projects, this report presents lessons learned from the projects

Thin-film cadmium telluride photovoltaics: ES and H issues, solutions, and perspectives

Photovoltaics (PV) is a growing business worldwide, with new technologies evolving towards potentially large-volume production. PV use produces no emissions, thus offsetting many potential environmental problems. However, the new PV technologies also bring unfamiliar environment, safety, and health (ES and H) challenges that require innovative solutions. This is a summary of the issues, solutions, and perspectives associated with the use of cadmium in one of the new and important PV technologies: thin-film, cadmium telluride (CdTe) PV, which is being developed and commercialized by several companies including Solar Cells Inc. (Toledo, Ohio), BP Solar (Fairfield, California), and Matsushita (Japan). The principal ES and H issue for thin-film cadmium telluride PV is the potential introduction of cadmium--a toxic heavy metal--into the air or water. The amount of cadmium in thin-film PV, however, is quite small--one nickel cadmium flashlight battery has about as much cadmium (7 g) as a square meter of PV module using current technology--and a typical cordless power tool will have 5--10 batteries. CdTe modules are also very well sealed, limiting the chance of release. Nonetheless, minimizing the amount of cadmium in cadmium telluride modules and preventing the introduction of that cadmium into the environment is a top priority for National Renewable Energy Laboratory researchers and cadmium telluride PV manufacturers

Streaming cold cosmic ray back-reaction and thermal instabilities across the background magnetic field

Using the multi-fluid approach, we investigate streaming and thermal instabilities of the electron-ion plasma with homogeneous cold cosmic rays drifting perpendicular to the background magnetic field. Perturbations across the magnetic field are considered. The back-reaction of cosmic rays resulting in the streaming instability is taken into account. The thermal instability is shown not to be subject to the action of cosmic rays in the model under consideration. The dispersion relation for the thermal instability has been derived which includes sound velocities of plasma and cosmic rays, Alfv\'{e}n and cosmic ray drift velocities. The relation between these parameters determines the kind of thermal instability from Parker's to Field's type instability. The results obtained can be useful for a more detailed the investigation of electron-ion astrophysical objects such as galaxy clusters including the dynamics of streaming cosmic rays.Comment: Submitted to MNRAS. arXiv admin note: substantial text overlap with arXiv:1203.573

Polycrystalline Thin Film Photovoltaics: From the Laboratory to Solar Fields; Preprint

We review the status of commercial polycrystalline thin-film solar cells and photovoltaic (PV) modules, including current and projected commercialization activities