High-energy particle transport in 3D hydrodynamic models of colliding-wind binaries

Massive stars in binary systems (as WR140, WR147 or $\eta$ Carinae) have long been regarded as potential sources of high-energy $\gamma$-rays. The emission is thought to arise in the region where the stellar winds collide and produce relativistic particles which subsequently might be able to emit $\gamma$-rays. Detailed numerical hydrodynamic simulations have already offered insight in the complex dynamics of the wind collision region (WCR), while independent analytical studies, albeit with simplified descriptions of the WCR, have shed light on the spectra of charged particles. In this paper, we describe a combination of these two approaches. We present a 3D-hydrodynamical model for colliding stellar winds and compute spectral energy distributions of relativistic particles for the resulting structure of the WCR. The hydrodynamic part of our model incorporates the line-driven acceleration of the winds, gravity, orbital motion and the radiative cooling of the shocked plasma. In our treatment of charged particles we consider diffusive shock acceleration in the WCR and the subsequent cooling via inverse Compton losses (including Klein-Nishina effects), bremsstrahlung, collisions and other energy loss mechanisms.Comment: 28 pages, 9 figures / accepted for publication in The Astrophysical Journa

X-ray and gamma-ray orbital variability from the gamma-ray binary HESS J1832-093

Context. Gamma-ray binaries are systems composed of a massive star and a compact object whose interaction leads to particle acceleration up to relativistic energies. In the last fifteen years, a few binaries have been discovered to emit at high energies, but their number is still scarce. The TeV source HESS J1832-093 has been proposed as a binary candidate, although its nature is unclear. Neither a GeV counterpart nor a period was found for it. Aims. The purpose of this work is to search for a gamma-ray source at GeV energies to understand the origin of the TeV signal. For an unambiguous identification of its binary nature, finding an orbital modulation is crucial. Methods. We have analysed data spanning more than 10 years from the Fermi Large Area Telescope (Fermi-LAT), together with Swift archival observations taken between 2015 and 2018, using both the X-Ray Telescope (XRT) and UltraViolet and Optical Telescope (UVOT). We searched for periodicities in both X-ray and gamma-ray bands using a Lomb-Scargle periodogram. Results. We find a periodic modulation of \sim 86 days in the X-ray source XMMU J183245-0921539, together with indications of gamma-ray modulation with a compatible period in 4FGL J1832.9-0913. Neither an optical nor an UV counterpart is found at the X-ray source location. The overall spectral energy distribution strongly resembles the known gamma-ray binary HESS J0632+057. Conclusions. Both the spectrum and the discovery of an orbital period allow the identification of the TeV source HESS J1832-093 as a new member of the gamma-ray binary class.Comment: 9 pages, 9 figures. Accepted by A&

A candidate gamma-ray pulsar in the supernova remnant CTA 1

We present a detailed analysis of the high energy gamma-ray source 2EG J0008+7307. The source has a steady flux and a hard spectrum, softening above 2 GeV. The properties of the gamma-ray source are suggestive of emission from a young pulsar in the spatially coincident CTA 1 supernova remnant, which has recently been found to have a non-thermal X-ray plerion. Our 95% uncertainty contour around the >1 GeV source position includes the point-like X-ray source at the centre of the plerion. We propose that this object is a young pulsar and is the most likely counterpart of 2EG J0008+7307.Comment: Accepted for publication in MNRAS. 6 pages including four PS figures. Uses mn.te

OTV bearing deflection investigation

The primary goal of the Bearing Deflectometer Investigation was to gain experience in the use of fiber optic displacement probe technology for bearing health monitoring in a liquid hydrogen turbo pump. The work specified in this Task Order was conducted in conjunction with Air Force Rocket Propulsion Laboratory Contract F04611-86-C-0010. APD conducted the analysis and design coordination to provide a displacement probe design compatible with the XLR-134 liquid hydrogen turbo pump assembly (TPA). Specifications and requirements of the bearing deflectometer were established working with Mechanical Technology Instruments, Inc. (MTI). The TPA design accommodated positioning of the probe to measure outer race cyclic deflections of the pump inlet bearing. The fiber optic sensor was installed as required in the TPA and sensor output was recorded during the TPA testing. Data review indicated that no bearing deflection signature could be differentiated from the inherent system noise. Alternate sensor installations were not investigated, but might yield different results

Non-adiabatic effects in periodically driven-dissipative open quantum systems

We present a general method to calculate the quasi-stationary state of a driven-dissipative system coupled to a transmission line (and more generally, to a reservoir) under periodic modulation of its parameters. Using Floquet's theorem, we formulate the differential equation for the system's density operator which has to be solved for a single period of modulation. On this basis we also provide systematic expansions in both the adiabatic and high-frequency regime. Applying our method to three different systems -- two- and three-level models as well as the driven nonlinear cavity -- we propose periodic modulation protocols of parameters leading to a temporary suppression of effective dissipation rates, and study the arising non-adiabatic features in the response of these systems.Comment: 12 pages, 8 figure

Who Should be Interviewed in Surveys of Household Income?

This study tests the null hypothesis that it is sufficient to interview only the household head to obtain accurate information on household income. Results show that using a husband’s estimate of his wife’s income does not produce statistically reliable results for poverty analysis. Estimates of the wife’s income provided by the husband and wife are in agreement in only six percent of households. While limiting interviews to one person has the advantage of reducing the time and expense of household surveys, this appears detrimental in terms of accuracy, and may lead to incorrect conclusions on the determinants of poverty.Africa, gender, household dynamics, household surveys, Malawi, poverty, Agricultural Finance,

The Monoceros very-high-energy gamma-ray source

The H.E.S.S. telescope array has observed the complex Monoceros Loop SNR/Rosette Nebula region which contains unidentified high energy EGRET sources and potential very-high-energy (VHE) gamma-ray source. We announce the discovery of a new point-like VHE gamma-ray sources, HESS J0632+057. It is located close to the rim of the Monoceros SNR and has no clear counterpart at other wavelengths. Data from the NANTEN telescope have been used to investigate hadronic interactions with nearby molecular clouds. We found no evidence for a clear association. The VHE gamma-ray emission is possibly associated with the lower energy gamma-ray source 3EG J0634+0521, a weak X-ray source 1RXS J063258.3+054857 and the Be-star MWC 148.Comment: 4 pages, 4 figures, Contribution to the 30th ICRC, Merida Mexico, July 200

SHCal13 Southern Hemisphere calibration, 0–50,000 years cal BP

The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the Northern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset

SHCal04 Southern Hemisphere Calibration, 0–11.0 cal kyr BP

Recent measurements on dendrochronologically-dated wood from the Southern Hemisphere have shown that there are differences between the structural form of the radiocarbon calibration curves from each hemisphere. Thus, it is desirable, when possible, to use calibration data obtained from secure dendrochronologically-dated wood from the corresponding hemisphere. In this paper, we outline the recent work and point the reader to the internationally recommended data set that should be used for future calibration of Southern Hemisphere ¹⁴C dates

The redshift-dependence of gamma-ray absorption in the environments of strong-line AGN

The case of gamma-ray absorption due to photon-photon pair production of jet photons in the external photon environment like accretion disk and broad-line region radiation field of gamma-ray loud active galactic nuclei (AGN) that exhibit strong emission lines is considered. I demonstrate that this ''local opacity'', if detected, will almost unavoidably be redshift-dependent in the sub-TeV range. This introduces non-negligible biases, and complicates approaches for studying the evolution of the extragalactic background light with contemporary GeV instruments like e.g. the Gamma-ray Large Area Space Telescope (GLAST), etc., where the gamma-ray horizon is probed by means of statistical analysis of absorption features (e.g. Fazio-Stecker relation, etc.) in AGN spectra at various redshifts. It particularly applies to strong-line quasars where external photon fields are potentially involved in gamma-ray production.Comment: 19 pages, 5 figures; accepted for publication in Ap