Soft versus Hard X-ray emission in AGN: partial covering and warm plus cold absorber models

We analyse the ROSAT PSPC hardness ratio and the 0.5-2 keV to 2-10 keV flux ratio of 65 Active Galactic Nuclei (AGN) for which there are both ROSAT archival observations available and 2-10 keV fluxes, mostly from the HEAO-1 MC-LASS survey. We conclude that the simplest spectral model for the AGN that can accommodate the variety of X-ray colours obtained is a standard power law (with energy spectral index $\alpha\sim 0.9$) plus a $\sim 0.1$ keV black body both partially absorbed. In our sample, type 1 AGN require an absorbing column around $10^{22}\, {\rm cm}^{-2}$ with covering fractions between 20 and 100\%, while type 2 AGN display larger columns and $\sim 100\%$ coverage. This simple model also provides a good link between soft and hard AGN X-ray luminosity functions and source counts. We also consider a warm absorber as an alternative model to partial covering and find that the the presence of gas in two phases (ionized and neutral) is required.Comment: 10 pages, Latex (mn.sty), 1 table, 5 figures included (epsf), postscript version also available via anonymous ftp at ftp://astsun1.unican.es/pub/ceballos/ . Accepted for publication in MNRA

The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue

Context. Sky surveys produce enormous quantities of data on extensive regions of the sky. The easiest way to access this information is through catalogues of standardised data products. XMM-Newton has been surveying the sky in the X-ray, ultra-violet, and optical bands for 20 years. Aims. The XMM-Newton Survey Science Centre has been producing standardised data products and catalogues to facilitate access to the serendipitous X-ray sky. Methods. Using improved calibration and enhanced software, we re-reduced all of the 14 041 XMM-Newton X-ray observations, of which 11 204 observations contained data with at least one detection and with these we created a new, high quality version of the XMM-Newton serendipitous source catalogue, 4XMM-DR9. Results. 4XMM-DR9 contains 810 795 detections down to a detection significance of 3σ, of which 550 124 are unique sources, which cover 1152 degrees² (2.85%) of the sky. Filtering 4XMM-DR9 to retain only the cleanest sources with at least a 5σ detection significance leaves 433 612 detections. Of these detections, 99.6% have no pileup. Furthermore, 336 columns of information on each detection are provided, along with images. The quality of the source detection is shown to have improved significantly with respect to previous versions of the catalogues. Spectra and lightcurves are also made available for more than 288 000 of the brightest sources (36% of all detections).FJC acknowledges financial support through grant AYA2015-64346-C2-1P (MINECO/FEDER).MTC and FJC acknowledge financial support from the Spanish Ministry MCIU under project RTI2018-096686-BC21 (MCIU/AEI/FEDER/UE) cofunded by FEDER funds and from the Agencia Estatal de Investigación, Unidad de Excelencia María de Maeztu, ref. MDM2017-0765

On the origin of the X-ray emission from a narrow-line radio quasar at z ; 1

We present new XMM?Newton X-ray observations of the z = 1.246 narrow-line radio quasar RX J1011.2+5545 serendipitously discovered by ROSAT. The flat X-ray spectrum previously measured by ROSAT and ASCA is shown to be the result of a steep ? 1.8 power-law spectrum seen through a moderate intrinsic absorbing column (N H ? 4 × 1021 cm?2). The position of the X-ray source is entirely coincident with the nucleus of the radio source that we have resolved in new sensitive VLA observations at 3.6 and 6 cm, implying that scattering in the radio lobes is not responsible for the bulk of X-ray emission. In the EPIC pn image, a faint patch of X-ray emission is apparent 14 arcsec to the north-east of the main X-ray source. The former is positionally coincident with an apparently extended optical object with R ? 21.9, but there is no associated radio emission, thus ruling out the possibility that this represents a hotspot in a jet emanating from the primary X-ray source. No reflection features are detected in the X-ray spectrum of the narrow-line radio quasar, although an Fe line with an equivalent width of up to 600 eV cannot be ruled out.The work reported herein is based partly on observations obtained with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the USA (NASA). The NOT telescope is operated by the Nordic Optical Telescope Scientific Association on the spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias. We are grateful to the service support for conducting the optical observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We acknowledge financial support by the Ministerio de Ciencia y Tecnolog´ıa (Spain), under grants AYA2000-1690 (XB, FJC, MTC), AYA2002-03326 (RC, JIGS) and AYA2001-3092 (MR, JMP). MR and JMP acknowledge also partial support by the European Regional Development Fund (ERDF/FEDER). During this work, MR has been supported by a fellowship from CIRIT (Generalitat de Catalunya, ref. 1999 F I 00199

The XMM-Newton serendipitous survey: VIII. the first XMM-Newton serendipitous source catalogue from overlapping observations

Context. XMM-Newton has observed the X-ray sky since early 2000. The XMM-Newton Survey Science Centre Consortium has published catalogues of X-ray and ultraviolet sources found serendipitously in the individual observations. This series is now augmented by a catalogue dedicated to X-ray sources detected in spatially overlapping XMM-Newton observations. Aims. The aim of this catalogue is to explore repeatedly observed sky regions. It thus makes use of the long(er) effective exposure time per sky area and offers the opportunity to investigate long-term flux variability directly through the source-detection process. Methods. A new standardised strategy for simultaneous source detection on multiple observations was introduced, including an adaptive-smoothing method to describe the image background. It was coded as a new task within the XMM-Newton Science Analysis System and used to compile a catalogue of sources from 434 stacks comprising 1789 overlapping XMM-Newton observations that entered the 3XMM-DR7 catalogue, have a low background and full-frame readout of all EPIC cameras. Results. The first stacked catalogue is called 3XMM-DR7s. It contains 71 951 unique sources with positions and parameters such as fluxes, hardness ratios, quality estimates, and information on inter-observation variability, directly derived from a simultaneous fit. Source parameters are calculated for the stack and for each contributing observation. About 15% of the sources are new with respect to 3XMM-DR7. Through stacked source detection, the parameters of repeatedly observed sources are determined with higher accuracy than in the individual observations. The method is more sensitive to faint sources and tends to produce fewer spurious detections. Conclusions. With this first stacked catalogue we demonstrate the feasibility and benefit of the approach. It supplements the large data base of XMM-Newton detections with additional, in particular faint, sources and adds variability information. In the future, the catalogue will be expanded to larger samples and continued within the series of serendipitous XMM-Newton source catalogues.FJC acknowledges financial support through grant AYA2015-64346-C2-1P (MINECO/FEDER) and MTC through grant ESP2016-76683-C3-1R (MINECO/FEDER

Straightforward purification method for the determination of the activity of glucose oxidase and catalase in honey by extracting polyphenols with a film-shaped polymer

Glucose oxidase (GOX) and catalase (CAT) regulate the amount of H2O2 in honey, by generating or consuming it, so they are related to the antibacterial and antioxidant activity of honey. However, their activities are hardly analysed, since the process requires a previous dialysis that is non-selective, very time-consuming (>24 h), eco-unfriendly (>6L of buffer) and expensive. This research shows the design and performance of a material that selectively removes the actual interferents. The film-shaped-polymer is immersed for 90́ within a honey solution (12.5 mL of buffer), where it interacts exclusively with 1,2-dihydroxybenzenes, which we proved to be the real interferents (the material contains motifs derived from phenylboronic acid to interact with 1,2-diols). Polymeric chains favour condensation to occur exclusively with 1,2-dihydroxybenzenes, excluding monosaccharides. The interferents’ removal using our designed polymer is selective, low cost (1.42€ per test), rapid and eco-friendly (saves 6L of buffer and 20.5 h of experimental workout per sample).We gratefully acknowledge the financial support provided by all funders. Author Jose Miguel García received grant PID2020-113264RB-I00 / AEI / 10.13039/501100011033 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. Ana Arnaiz received funding from Ministerio de Universidades-European Union in the frame of NextGenerationEU RD 289/2021 (Universidad Politécnica de Madrid). We also gratefully acknowledge European Regional Development Fund (ERDF). Gianluca Utzeri thanks Fundação para a Ciência e a Tecnologia (FCT, Portugal) for PhD grant (SFR/BD/146358/2019). The Coimbra Chemistry Centre is supported by the FCT, through Projects UIDB/00313/2020 and UIDP/00313/2020. To all the beekeepers who provided a sample of honey for this study