Soft X-ray emission from an anharmonic collisional nanoplasma by a laser–nanocluster interaction

The purpose of the present paper is to investigate the generation of soft X-ray emission from an anharmonic collisional nanoplasma by a laser–nanocluster interaction. The electric field of the laser beam interacts with the nanocluster and leads to ionization of the cluster atoms, which then produces a nanoplasma. Because of the nonlinear restoring force in an anharmonic nanoplasma, the fluctuations and heating rate of, as well as the power radiated by, the electrons in the nanocluster plasma will be notably different from those arising from a linear restoring force. By comparing the nonlinear restoring force state (which arises from an anharmonic cluster) with that of the linear restoring force (in harmonic clusters), the cluster temperature specifically changes at the resonant frequency relative to the linear restoring force, while the variation of the anharmonic cluster radius is almost identical to that of the harmonic cluster radius. In addition, it is revealed that a sharp peak of X-ray emission arises after some picoseconds in deuterium, helium, neon and argon clusters.

Successful Indoor Mass Storage of Honeybee Queens (Apis mellifera) during Winter

The production of young, mated honeybee queens (Apis mellifera) is essential to replace dead queens or to start new colonies after wintering. Mass storage of mated honeybee queens during winter and their use the following spring is an interesting strategy that could help fulfill this need. In this study, we investigated the survival, fertility, and fecundity of young, mated queens stored massively in queenless colonies from September to April (eight months). The queens were kept in environmentally controlled rooms at temperatures above and below cluster formation. The results show that indoor mass storage of mated queens can be achieved with success when queen banks are stored above cluster temperature. Significantly higher survival of queens was measured when wintering queen banks at 16 °C. Surviving queens wintered at different temperatures above or below cluster formation had similar fertility (sperm viability) and fecundity (egg laying and viable worker population). This study shows the potential of indoor overwintering of honeybee queen banks. The technique we describe could be applied on a commercial scale by beekeepers and queen breeders.

X-ray study of the merging galaxy cluster Abell 3411-3412 with XMM-Newton and Suzaku

Context. Previous Chandra observations of the Abell 3411-3412 merging galaxy cluster system revealed an outbound bullet-like sub-cluster in the northern part and many surface brightness edges at the southern periphery, where multiple diffuse sources are also reported from radio observations. Notably, a southeastern radio relic associated with fossil plasma from a radio galaxy and with a detected X-ray edge provides direct evidence of shock re-acceleration. The properties of the reported surface brightness features have yet to be constrained from a thermodynamic viewpoint. Aims. We use the XMM-Newton and Suzaku observations of Abell 3411-3412 to reveal the thermodynamical nature of the previously reported re-acceleration site and other X-ray surface brightness edges. We also aim to investigate the temperature profile in the low-density outskirts with Suzaku data. Methods. We performed both imaging and spectral analysis to measure the density jump and the temperature jump across multiple known X-ray surface brightness discontinuities. We present a new method to calibrate the vignetting function and spectral model of the XMM-Newton soft proton background. Archival Chandra, Suzaku, and ROSAT data are used to estimate the cosmic X-ray background and Galactic foreground levels with improved accuracy compared to standard blank sky spectra. Results. At the southeastern edge, temperature jumps revealed by both XMM-Newton and Suzaku point to a ℳ ∼ 1.2 shock, which agrees with the previous result from surface brightness fits with Chandra. The low Mach number supports the re-acceleration scenario at this shock front. The southern edge shows a more complex scenario, where a shock and the presence of stripped cold material may coincide. There is no evidence for a bow shock in front of the northwestern “bullet” sub-cluster. The Suzaku temperature profiles in the southern low-density regions are marginally higher than the typical relaxed cluster temperature profile. The measured value kT500 = 4.84 ± 0.04 ± 0.19 keV with XMM-Newton and kT500 = 5.17 ± 0.07 ± 0.13 keV with Suzaku are significantly lower than previously inferred from Chandra.

Relativistic SZ temperature scaling relations of groups and clusters derived from the BAHAMAS and MACSIS simulations

ABSTRACT The Sunyaev–Zeldovich (SZ) effect has long been recognized as a powerful cosmological probe. Using the BAHAMAS and MACSIS simulations to obtain ${\gt }10\, 000$ simulated galaxy groups and clusters, we compute three temperature measures and quantify the differences between them. The first measure is related to the X-ray emission of the cluster, while the second describes the non-relativistic thermal SZ (tSZ) effect. The third measure determines the lowest order relativistic correction to the tSZ signal, which is seeing increased observational relevance. Our procedure allows us to accurately model the relativistic SZ (rSZ) contribution and we show that a ${\gtrsim}10\!-\!40{{\ \rm per\ cent}}$ underestimation of this rSZ cluster temperature is expected when applying standard X-ray relations. The correction also exhibits significant mass and redshift evolution, as we demonstrate here. We present the mass dependence of each temperature measure alongside their profiles and a short analysis of the temperature dispersion as derived from the aforementioned simulations. We also discuss a new relation connecting the temperature and Compton-y parameter, which can be directly used for rSZ modelling. Simple fits to the obtained scaling relations and profiles are provided. These should be useful for future studies of the rSZ effect and its relevance to cluster cosmology.