SNR 1E 0102.2-7219 as an X-ray calibration standard in the 0.5−1.0 keV bandpass and its application to the CCD instruments aboard Chandra , Suzaku , Swift and XMM-Newton

Context. The flight calibration of the spectral response of charge-coupled device (CCD) instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. This calibration is also a function of time due to the effects of radiation damage on the CCDs and/or the accumulation of a contamination layer on the filters or CCDs. Aims. We desire a simple comparison of the absolute effective areas of the current generation of CCD instruments onboard the following observatories: Chandra ACIS-S3, XMM-Newton (EPIC-MOS and EPIC-pn), Suzaku XIS, and Swift XRT and a straightforward comparison of the time-dependent response of these instruments across their respective mission lifetimes. Methods. We have been using 1E 0102.2-7219, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate and modify the response models of these instruments. 1E 0102.2-7219 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of 1E 0102.2-7219 has been well-characterized using the RGS gratings instrument on XMM-Newton and the HETG gratings instrument on Chandra. As part of the activities of the International Astronomical Consortium for High Energy Calibration (IACHEC), we have developed a standard spectral model for 1E 0102.2-7219 and fit this model to the spectra extracted from the CCD instruments. The model is empirical in that it includes Gaussians for the identified lines, an absorption component in the Galaxy, another absorption component in the SMC, and two thermal continuum components with different temperatures. In our fits, the model is highly constrained in that only the normalizations of the four brightest lines/line complexes (the O vii Heα triplet, O viii Lyα line, the Ne ix Heα triplet, and the Ne x Lyα line) and an overall normalization are allowed to vary, while all other components are fixed. We adopted this approach to provide a straightforward comparison of the measured line fluxes at these four energies. We have examined these measured line fluxes as a function of time for each instrument after applying the most recent calibrations that account for the time-dependent response of each instrument. Results. We performed our effective area comparison with representative, early mission data when the radiation damage and contamination layers were at a minimum, except for the XMM-Newton EPIC-pn instrument which is stable in time. We found that the measured fluxes of the O vii Heαr line, the O viii Lyα line, the Ne ix Heαr line, and the Ne x Lyα line generally agree to within ±10% for all instruments, with 38 of our 48 fitted normalizations within ± 10% of the IACHEC model value. We then fit all available observations of 1E 0102.2-7219 for the CCD instruments close to the on-axis position to characterize the time dependence in the 0.5−1.0 keV band. We present the measured line normalizations as a function of time for each CCD instrument so that the users may estimate the uncertainty in their measured line fluxes for the epoch of their observations

EFSA is working to protect bees and shape the future of environmental risk assessment

Europe is pursuing its ambition for a climate-neutral, sustainable future. The European Commission’s Green Deal, an important step in this direction, has at its heart the protection of the European Union (EU)’s biodiversity and the resilience of its ecosystems. Reducing the use and risk of pesticides and reversing the decline of pollinators are but two of the ‘calls-to-action’ embedded, respectively, in the Green Deal’s Farm to Fork and Biodiversity Strategies. Much of the science supporting policymakers on these highly complex bodies of work falls within the remit of the European Food Safety Authority (EFSA). EFSA scientists are working to help address these challenges, as reflected in the release in 2021 of two important scientific reports. The first report addresses a mandate from the European Commission for a review of the 2013 bee guidance document on the risk assessment of pesticides in relation to honey bees, bumble bees and solitary bees; the second responds to the European Parliament’s request for a scientific opinion on the development of an integrated and holistic approach for the environmental risk assessment (ERA) of multiple stressors in managed honey bees (Apis mellifera) – known as the MUST-B project

On-chip wideband tunable RF photonic phase shifter based on stimulated Brillouin scattering

We demonstrate for the first time an RF photonic phase shifter using stimulated Brillouin scattering on chip, with wide bandwidth operation. We achieve 180° phase shift range over 2-15 GHz frequency band

Tunable wideband microwave photonic phase shifter using on-chip stimulated Brillouin scattering

We present the first microwave photonic phase shifter using stimulated Brillouin scattering (SBS) on-chip. The unique ability of SBS to generate both narrowband gain and loss resonances allows us to achieve low ±1.5 dB amplitude fluctuations, which is a record for integrated devices, along with 240° continuously tunable phase shift. Contrary to previous SBS-based approaches, the phase shift tuning mechanism relies on tuning the power, not the frequency, of two SBS pumps, making it more suited to on-chip implementations. We finally demonstrate that SBS pump depletion leads to amplitude response fluctuations, as well as increasing the insertion loss of the phase shifter. Advantageously, shorter integrated platforms possess higher pump depletion thresholds compared to long fibers, thus offering greater potential for reducing the insertion loss.This work was funded by the Australian Research Council (ARC) through its Centre of Excellence CUDOS (Grant Number CE110001018), Laureate Fellowship (FL120100029), and Future Fellowship (FT110100853)

Advanced Integrated Microwave Signal Processing with Giant On-Chip Brillouin Gain

Processing of microwave signals using photonics has several key advantages for applications in wireless communications. However, to bring photonic-based microwave signal processing to the mainstream requires a reduction of the form factor. Integration is a route for achieving high-performance, low-cost, and small-footprint microwave photonic devices. A high on-chip stimulated Brillouin scattering (SBS) gain is essential for synthesizing several key functionalities for advanced integrated microwave signal processing. We have optimized our on-chip SBS platform to achieve a record on-chip gain of 52 dB. In this paper, we discuss the implications of this giant gain from the viewpoint of new enabled technologies. The giant gain can be distributed over wide frequencies, which can be exploited for the realization of reconfigurable microwave bandpass, bandstop, and multiband filters. High gain also enables the demonstration of low-threshold on-chip lasers, which can be of relevance for a low-noise radio-frequency signal generation. These wide ranges of functionalities are made possible by the breakthrough on-chip gain makes Brillouin-based microwave photonic signal processing a promising approach for real-world implementation in the near future

Energy efficient RF signal processing with on-chip stimulated brillouin scattering**

Here we show the first chip-based RF photonic band-stop filter with ultra-high suppression, high resolution, and 1-30 GHz frequency tuning. This record performance was achieved using an ultra-low Brillouin gain from a compact photonic chip

Low-power, chip-based stimulated Brillouin scattering microwave photonic filter with ultrahigh selectivity

Highly selective and reconfigurable microwave filters are of great importance in radio-frequency signal processing. Microwave photonic (MWP) filters are of particular interest, as they offer flexible reconfiguration and an order of magnitude higher frequency tuning range than electronic filters. However, all MWP filters to date have been limited by trade-offs between key parameters such as tuning range, resolution, and suppression. This problem is exacerbated in the case of integrated MWP filters, blocking the path to compact, high-performance filters. Here we show the first chip-based MWP bandstop filter with ultrahigh suppression, high resolution in the megahertz range, and 0–30 GHz frequency tuning. This record performance was achieved using an ultralow Brillouin gain from a compact photonic chip and a novel approach of optical resonance-assisted RF signal cancellation. The results point to new ways of creating energy-efficient and reconfigurable integrated MWP signal processors for wireless communications and defence applications