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Despite the importance of the dusty star-forming galaxies (DSFGs) at $z$>2 for understanding the galaxy evolution in the early Universe, their stellar distributions traced by the near-IR emission were spatially unresolved until the arrival of the JWST. In this work we present, for the first time, a spatially-resolved morphological analysis of the rest-frame near-IR (~1.1-3.5$\mu$m) emission in DSFGs traced with the JWST/MIRI. In particular, we study the mature stellar component for the three DSFGs and a Lyman-break galaxy (LBG) present in an overdensity at $z$=4.05. Moreover, we use MIRI images along with UV to (sub)-mm ancillary photometric data to model their SEDs and extract their main physical properties. The sub-arcsec resolution MIRI images have revealed that the stellar component present a wide range of morphologies, from disc-like to compact and clump-dominated structures. These near-IR structures contrast with their UV emission, which is usually diffuse and off-centered. The SED fitting analysis shows that GN20 dominates the total SFR with a value ~2500 $M_\odot$yr$^{-1}$ while GN20.2b has the highest stellar mass in the sample ($M_*$~2$\times$10$^{11}$ $M_\odot$). The two DSFGs classified as LTGs (GN20 and GN20.2a) show high specific SFR (sSFR>30 Gyr$^{-1}$) placing them above the star-forming main sequence (SFMS) at z~4 by >0.5 dex while the ETG (i.e.,GN20.2b) is compatible with the high-mass end of the main sequence. When comparing with other DSFGs in overdensities at $z$~2-7 we observe that our objects present similar SFRs, depletion times and projected separations. Nevertheless, the effective radii computed for our DSFGs (~3 kpc) are up to two times larger than those of isolated galaxies observed in CEERS and ALMA-HUDF at similar redshifts. We interpret this difference as an effect of rapid growth induced by the dense environment., Comment: 14 pages, 6 figures

We make use of JWST medium-band and broadband NIRCam imaging, along with ultradeep MIRI 5.6 mu m imaging, in the Hubble eXtreme Deep Field to identify prominent line emitters at z similar or equal to 7-8. Out of a total of 58 galaxies at z similar or equal to 7-8, we find 18 robust candidates ( similar or equal to 31%) for (H beta + [O III]) emitters, based on their enhanced fluxes in the F430M and F444W filters, with EW0(H beta +[O III]) similar or equal to 87-2100 angstrom. Among these emitters, 16 lie in the MIRI coverage area and 12 exhibit a clear flux excess at 5.6 mu m, indicating the simultaneous presence of a prominent Ha emission line with EW0(H alpha) similar or equal to 200-3000 angstrom. This is the first time that H alpha emission can be detected in individual galaxies at z > 7. The Ha line, when present, allows us to separate the contributions of H beta and [O III] to the (H beta +[O III]) complex and derive Ha-based star formation rates (SFRs). We find that in most cases [O III]/ H beta > 1. Instead, two galaxies have [O III]/H beta < 1, indicating that the NIRCam flux excess is mainly driven by H beta. Most prominent line emitters are very young starbursts or galaxies on their way to/from the starburst cloud. They make for a cosmic SFR density log(10)( rho(SFRH alpha) (M-circle dot yr(-1) Mpc))similar or equal to - 2.351 3 which is about a quarter of the total value (log(10)( SFR (M-circle dot yr(-1) Mpc))similar or equal to - 1.761 3 ) at z similar or equal to 7-8. Therefore, the strong Ha emitters likely had a significant role in reionization.

Luminous infrared galaxies at high redshifts (z > 4) include extreme starbursts that build their stellar mass over short periods of time, that is, of 100 Myr or less. These galaxies are considered to be the progenitors of massive quiescent galaxies at intermediate redshifts (z similar to 2) but their stellar structure and buildup is unknown. Here, we present the first spatially resolved near-infrared (rest-frame 1.1 mu m) imaging of GN20, one of the most luminous dusty star-forming galaxies known to date, observed at an epoch when the Universe was only 1.5 Gyr old. The 5.6 mu m image taken with the JWST Mid-Infrared Instrument (MIRI/JWST) shows that GN20 is a very luminous galaxy (M-1.1 mu m,M- AB = 25.01, uncorrected for internal extinction), with a stellar structure composed of a conspicuous central source and an extended envelope. The central source is an unresolved nucleus that carries 9% of the total flux. The nucleus is co-aligned with the peak of the cold dust emission, and offset by 3.9 kpc from the ultraviolet stellar emission. The diffuse stellar envelope is similar in size (3.6 kpc effective radius) to the clumpy CO molecular gas distribution. The centroid of the stellar envelope is offset by 1 kpc from the unresolved nucleus, suggesting GN20 is involved in an interaction or merger event supported by its location as the brightest galaxy in a proto-cluster. Additional faint stellar clumps appear to be associated with some of the UV- and CO-clumps. The stellar size of GN20 is larger by a factor of about 3 to 5 than known spheroids, disks, and irregulars at z similar to 4, while its size and low Sersic index are similar to those measured in dusty, infrared luminous galaxies at redshift 2 of the same mass (similar to 10(11) M-circle dot). GN20 has all the ingredients necessary for evolving into a massive spheroidal quiescent galaxy at intermediate redshift: it is a large, luminous galaxy at z = 4.05 involved in a short and massive starburst centred in the

By using the ultra-deep \textit{JWST}/MIRI image at 5.6 $\mu m$ in the Hubble eXtreme Deep Field, we constrain the role of strong H$\alpha$-emitters (HAEs) during Cosmic Reionization at $z\simeq7-8$. Our sample of HAEs is comprised of young ($<35\;\rm Myr$) galaxies, except for one single galaxy ($\approx 300\;\rm Myr$), with low stellar masses ($\lesssim 10^{9}\;\rm M_{\odot}$). These HAEs show a wide range of UV-$\beta$ slopes, with a median value of $\beta = -2.07\pm0.20$ which broadly correlates with stellar mass. We estimate the ionizing photon production efficiency ($\xi_{ion,0}$) of these sources (assuming $f_{esc,LyC} = 0\%$), which yields a median value $\rm log_{10}(\xi_{ion,0}/(Hz\;erg^{-1})) = 25.49^{+0.10}_{-0.12}$. We show that $\xi_{ion,0}$ positively correlates with EW$_{0}$(H$\alpha$) and specific star formation rate (sSFR). Instead $\xi_{ion,0}$ weakly anti-correlates with stellar mass and $\beta$. Based on the $\beta$ values, we predict $f_{esc, LyC}=4\%^{+2}_{-1}$, which results in $\rm log_{10}(\xi_{ion}/(Hz\;erg^{-1})) = 25.52^{+0.09}_{-0.08}$. Considering this and related findings from the literature, we find a mild evolution of $\xi_{ion}$with redshift. Additionally, our results suggest that these HAEs require only modest escape fractions ($f_{esc, rel}$) of 6$-$14\% to reionize their surrounding intergalactic medium. By only considering the contribution of these HAEs, we estimated their total ionizing emissivity ($\dot{N}_{ion}$) as $\dot{N}_{ion} = 10^{50.59 \pm 0.45}; \text{s}^{-1}\text{Mpc}^{-3}$. When comparing their $\dot{N}_{ion}$ with non-H$\alpha$ emitter galaxies across the same redshift range, we find that that strong, young, and low-mass emitters may have played an important role during Cosmic Reionization., Comment: 21 pages, 11 Figures, 1 table. Revised version submitted in ApJ

We present MIRI/JWST medium-resolution spectroscopy (MRS) and imaging (MIRIM) of the lensed galaxy MACS1149-JD1 at a redshift of $z$=9.1092$\pm$0.0002 (Universe age about 530 Myr). We detect, for the first time, spatially resolved H$\alpha$ emission in a galaxy at a redshift above nine. The structure of the H$\alpha$ emitting gas consists of two clumps, S and N. The total H$\alpha$ luminosity implies an instantaneous star-formation of 5.3$\pm$0.4 $M_{\odot}$ yr$^{-1}$ for solar metallicities. The ionizing photon production efficiency, $\log(\zeta_\mathrm{ion})$, shows a spatially resolved structure with values of 25.55$\pm$0.03, 25.47$\pm$0.03, and 25.91$\pm$0.09 Hz erg$^{-1}$ for the integrated galaxy, and clumps S and N, respectively. The H$\alpha$ rest-frame equivalent width, EW$_{0}$(H$\alpha$), is 726$^{+660}_{-182}$ \'Angstrom for the integrated galaxy, but presents extreme values of 531$^{+300}_{-96}$ \'Angstrom and $\geq$1951 \'Angstrom for clumps S and N, respectively. The spatially resolved ionizing photon production efficiency is within the range of values measured in galaxies at redshift above six, and well above the canonical value (25.2$\pm$0.1 Hz erg$^{-1}$). The extreme difference of EW$_{0}$(H$\alpha$) for Clumps S and N indicates the presence of a recent (<5 Myrs) burst in clump N and a star formation over a larger period of time (e.g., $\sim$50 Myr) in clump S. Finally, clump S and N show very different H$\alpha$ kinematics with velocity dispersions of 56$\pm$4 km s$^{-1}$ and 113$\pm$33 km s$^{-1}$, likely indicating the presence of outflows or increased turbulence in the clump N. The dynamical mass, $M_\mathrm{dyn}$= (2.4$\pm$0.5)$\times$10$^{9}$ $M_{\odot}$, is within the range measured with the spatially resolved [OIII]88$\mu$m line., Comment: 11 pages, 6 figures, published version in A&A

Using MIRI on-board JWST we present mid-infrared sub-arcsec imaging (MIRIM) and spectroscopy (MRS) of the hyperluminous infrared system SPT0311-58 at z=6.9. MIRI observations are compared with existing ALMA far-infrared continuum and [CII]158$\mu$m imaging. Even though the ALMA observations suggests very high star formation rates (SFR) in the eastern (E) and western (W) galaxies of the system, the H$\alpha$ line is not detected. This, together with the detection of the Pa$\alpha$ line, implies very high optical nebular extinction with lower limits of 4.2 (E) and 3.9 mag (W), and even larger 5.6 (E) and 10.0 (W) for SED derived values. The extinction-corrected Pa$\alpha$ SFRs are 383 and 230M$_{\odot}$yr$^{-1}$ for the E and W galaxies, respectively. This represents 50% of the SFRs derived from the [CII]158$\mu$m line and infrared light for the E galaxy and as low as 6% for the W galaxy. The MIRI observations reveal a clumpy stellar structure, with each clump having 3 to 5 $\times$10$^{9}$M$_\mathrm{\odot}$, leading to a total stellar mass of 2.0 and 1.5$\times$10$^{10}$M$_\mathrm{\odot}$ for the E and W galaxies, respectively. The specific SFR in the stellar clumps ranges from 25 to 59Gyr$^{-1}$, which are 3 to 10 times larger than the values measured in galaxies of similar mass at redshifts 6 to 8. The overall gas mass fraction is $M_\mathrm{gas}$/$M_*\sim3$, similar to that of z=4.5-6 star-forming galaxies. The observed properties of SPT0311-58 such as the clumpy distribution at sub(kpc) scales and the very high average extinction are similar to those observed in low- and intermediate-z LIRGs and ULIRGs, even though SPT0311-58 is observed only 800 Myr after the Big Bang. Massive, heavily obscured, clumpy starburst systems like SPT0311-58 likely represent the early phases in the formation of massive high-z bulge/spheroids and luminous quasars., Comment: 18 pages, 8 figures, final published version in A&A

Dusty star-forming galaxies emit most of their light at far-IR to mm wavelengths as their star formation is highly obscured. Far-IR and mm observations have revealed their dust, neutral and molecular gas properties. The sensitivity of JWST at rest-frame optical and near-infrared wavelengths now allows the study of the stellar and ionized gas content. We investigate the spatially resolved distribution and kinematics of the ionized gas in GN20, a dusty star forming galaxy at $z$=4.0548. We present deep MIRI/MRS integral field spectroscopy of the near-infrared rest-frame emission of GN20. We detect spatially resolved \paa, out to a radius of 6 kpc, distributed in a clumpy morphology. The star formation rate derived from \paa\ (144 $\pm$ 9 \msunperyear) is only 7.7 $\pm 0.5 $\% of the infrared star formation rate (1860 $\pm$ 90 \msunperyear). We attribute this to very high extinction (A$_V$ = 17.2 $\pm$ 0.4 mag, or A$_{V,mixed}$ = 44 $\pm$ 3 mag), especially in the nucleus of GN20, where only faint \paa\ is detected, suggesting a deeply buried starburst. We identify four, spatially unresolved, clumps in the \paa\ emission. Based on the double peaked \paa\ profile we find that each clump consist of at least two sub-clumps. We find mass upper limits consistent with them being formed in a gravitationally unstable gaseous disk. The UV bright region of GN20 does not have any detected \paa\ emission, suggesting an age of more than 10 Myrs for this region of the galaxy. From the rotation profile of \paa\ we conclude that the gas kinematics are rotationally dominated and the $v_{rot}/\sigma_{m} = 3.8 \pm 1.4$ is similar to low-redshift LIRGs. We speculate that the clumps seen in GN20 could contribute to building up the inner disk and bulge of GN20., Comment: 13 pages, 7 figures, accepted for publication in A&A

High-temperature receivers are critical for third-generation (Gen3) Concentrating Solar Power (CSP) technology to achieve high system efficiencies, and play the role of converting concentrated sunlight into heat. In this paper, two CSP systems with different working fluids in the receiver are examined in order to achieve identical supply of heat to the power block: a direct high-temperature chloride salt system and an indirect high-temperature sodium receiver with an associated heat exchanger to heat the same chloride salt. The presented numerical model indicates that the indirect sodium-salt system has a 4.37% higher exergy efficiency than the direct chloride salt system. The exergy destruction in the added sodium-salt heat exchanger was only 0.54%, which did not outweigh the performance benefits gained from using a sodium receiver, when compared to the direct salt case with no heat exchanger. Even at lower DNIs, the better heat-transfer characteristics of the sodium are responsible for its improved performance compared to salt in the receivers., QC 20220914Part of proceedings: ISBN 978-073544195-8

Bio‐logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio‐logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio‐logging data into research and management recommendations. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable; and TRUST: Transparency, Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy‐of‐use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing examples of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and inter‐governmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader

Temporal variability in flux and spectral shape is ubiquitous in the X-ray sky and carries crucial information about the nature and emission physics of the sources. The EPIC instrument on board the XMM-Newton observatory is the most powerful tool for studying variability even in faint sources. Each day, it collects a large amount of information about hundreds of new serendipitous sources, but the resulting huge (and growing) dataset is largely unexplored in the time domain. The project called Exploring the X-ray transient and variable sky (EXTraS) systematically extracted all temporal domain information in the XMM-Newton archive. This included a search and characterisation of variability, both periodic and aperiodic, in hundreds of thousands of sources spanning more than eight orders of magnitude in timescale and six orders of magnitude in flux, and a search for fast transients that were missed by standard image analysis. All results, products, and software tools have been released to the community in a public archive. A science gateway has also been implemented to allow users to run the EXTraS analysis remotely on recent XMM datasets. We give details on the new algorithms that were designed and implemented to perform all steps of EPIC data analysis, including data preparation, source and background modelling, generation of time series and power spectra, and search for and characterisation of different types of variabilities. We describe our results and products and give information about their basic statistical properties and advice on their usage. We also describe available online resources. The EXTraS database of results and its ancillary products is a rich resource for any kind of investigation in almost all fields of astrophysics. Algorithms and lessons learnt from our project are also a very useful reference for any current and future experiment in the time domain., Comment: 39 pages; accepted for publication in Astronomy & Astrophysics

We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift $56$ and redshifts $05$ galaxy samples can be reduced to $<0.01$ arcmin$^{-2}$ with a limited impact on galaxy completeness. We investigate multiple high-redshift galaxy selection techniques and find the best compromise between completeness and purity at $5

We perform optical analyses on multi-Aperture solar central receiver systems with compound parabolic concentrators to increase the power level for better economics., QC 20210323

A multi-aperture solar central receiver system is optically analyzed for increasing the net power to the receiver in a wide temperature range of 600-1800 K. A model system comprises a tower, a multi-aperture receiver with compound parabolic concentrators, and heliostat sub-fields. Optical modeling is performed using in-house developed Monte-Carlo ray-tracing programs. The heliostat sub-field geometrical configuration, the number of receiver apertures and optical properties of reflective surfaces are varied in the parametric study. Increasing the number of apertures from one to four increases the maximum net receiver power from 116MW to 332MW. The use of more than four apertures results in only limited further gain of the net receiver power but significantly decreases the overall optical efficiency and the solar-to-thermal efficiency. The optimal temperature for the maximized annual solar-to-exergy efficiency is found in the range of 1100-1200 K. This optimal temperature decreases slightly with an increasing number of apertures., QC 20210311

We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift 5 > z > 12 galaxies through extensive image simulations of accepted JWST programs, including the Early Release Science in the EGS field and the Guaranteed Time Observations in the HUDF. We introduced complete samples of ∼300 000 galaxies with stellar masses of log(M∗/M⊙)> 6 and redshifts of 0 < z< 15, as well as galactic stars, into realistic mock NIRCam, MIRI, and HST images to properly describe the impact of source blending. We extracted the photometry of the detected sources, as in real images, and estimated the physical properties of galaxies through spectral energy distribution fitting. We find that the photometric redshifts are primarily limited by the availability of blue-band and nearinfrared medium-band imaging. The stellar masses and star formation rates are recovered within 0.25 and 0.3 dex, respectively, for galaxies with accurate photometric redshifts. Brown dwarfs contaminating the z > 5 galaxy samples can be reduced to >0:01 arcmin-2 with a limited impact on galaxy completeness.We investigate multiple high-redshift galaxy selection techniques and find that the best compromise between completeness and purity at 5 < z < 10 using the full redshift posterior probability distributions. In the EGS field, the galaxy completeness remains higher than 50% at magnitudes mUV < 27:5 and at all redshifts, and the purity is maintained above 80 and 60% at z ≥ 7 and 10, respectively. The faint-end slope of the galaxy UV luminosity function is recovered with a precision of 0.1-0.25, and the cosmic star formation rate density within 0.1 dex. We argue in favor of additional observing programs covering larger areas to better constrain the bright end.

The James Webb Space Telescope (JWST) will provide deep imaging and spectroscopy for sources at redshifts above 6, covering the entire Epoch of Reionization (EoR, 6 < z < 10), and enabling the detailed exploration of the nature of the different sources during the first 1 Gyr of the history of the Universe. The Medium Resolution Spectrograph (MRS) of the mid-IR Instrument (MIRI) will be the only instrument on board JWST able to observe the brightest optical emission lines Hα and [OIII]0.5007 μm at redshifts above 7 and 9, respectively, providing key insights into the physical properties of sources during the early phases of the EoR. This paper presents a study of the Hα fluxes predicted by state-of-the-art FIRSTLIGHT cosmological simulations for galaxies at redshifts of 6.5–10.5, and its detectability with MIRI. Deep (40 ks) spectroscopic integrations with MRS will be able to detect (signal-to-noise ratio > 5) EoR sources at redshifts above 7 with intrinsic star formation rates (SFR) of more than 2 M⊙ yr−1, and stellar masses above 4–9 × 107 M⊙. These limits cover the upper end of the SFR and stellar mass distribution at those redshifts, representing ∼6% and ∼1% of the predicted FIRSTLIGHT population at the 6.5–7.5 and 7.5–8.5 redshift ranges, respectively. In addition, the paper presents realistic MRS simulated observations of the expected rest-frame optical and near-infrared spectra for some spectroscopically confirmed EoR sources recently detected by ALMA as [OIII]88 μm emitters. The MRS simulated spectra cover a wide range of low metallicities from about 0.2–0.02 Z⊙, and different [OIII]88 μm/[OIII]0.5007 μm line ratios. The simulated 10 ks MRS spectra show S/N in the range of 5–90 for Hβ, [OIII]0.4959,0.5007 μm, Hα and HeI1.083 μm emission lines of the currently highest spectroscopically confir

Context. Quasi-periodic pulsations (QPPs) are time variations in the energy emission during a flare that are observed on both the Sun and other stars and thus have the potential to link the physics of solar and stellar flares. Aims. To characterise the QPPs detected in an X-ray flare on the solar analogue, EK Draconis, which was observed by XMM-Newton. Methods. We use wavelet and autocorrelation techniques to identify the QPPs in a detrended version of the flare. We also fit a model to the flare based on an exponential decay combined with a decaying sinusoid. The flare is examined in multiple energy bands. Results. A statistically significant QPP is observed in the X-ray energy band of 0.2-12.0 keV with a periodicity of 76+/-2 min. When this energy band is split, a statistically significant QPP is observed in the low-energy band (0.2-1.0 keV) with a periodicity of 73+/-2 min and in the high-energy band (1.0-12.0 keV) with a periodicity of 82+/-2 min. When fitting a model to the time series the phases of the signals are also found to be significantly different in the two energy bands (with a difference of 1.8+/-0.2 rad) and the high-energy band is found to lead the low-energy band. Furthermore, the first peak in the cross-correlation between the detrended residuals of the low- and high-energy bands is offset from zero by more than 3{\sigma} (4.1+/-1.3 min). Both energy bands produce statistically significant regions in the wavelet spectrum, whose periods are consistent with those listed above. However, the peaks are broad in both the wavelet and global power spectra, with the wavelet showing evidence for a drift in period with time, and the difference in period obtained is not significant. etc..., Comment: Accepted for publication in A&A, 19 pages, 17 figures

Health and social care professionals are required to work together to deliver person-centered care. Professionals therefore find themselves making decisions within multidisciplinary teams. For educators, there has been a call to bring students from differing professions together to learn to enable more effective teamwork, interprofessional communication, and collaborative practice. This multidisciplinary working is complicated by the increasingly complex nature of ethical dilemmas that health and social care professionals face. It is therefore widely recognized that the teaching and learning of ethics within health and social care courses is valuable. In this paper, we briefly make the case in support of teaching and learning health and social care ethics through the medium of interprofessional education (IPE). The purpose of this paper is to provide guidance to educators intending to design ethics-orientated IPE for health and social care students. The guidance is based on the ongoing experiences of designing and implementing ethics-orientated IPE across five departments within two universities located in the North of England over a five-year period. Descriptions of the ethics-orientated IPE activities are included in the guide, along with key resources recommended.

We present results of X-ray spectral and timing analyses of solar-like (spectral types F5-K8) and intermediate-type (B4-F4) Pleiads observed in a 40-ks XMM-Newton EPIC exposure, probing X-ray luminosities (LX) up to a factor 10 fainter than previous studies using the ROSAT PSPC. All eight solar-like members have ‘quasi-steady'LX≳ 1029erg s−1, consistent with the known rotation-activity relation and four exhibit flares. Using a hydrodynamic modelling technique, we derive loop half-lengths for the two strongest flares, on H ii 1032 and H ii 1100. Near the beginning of its flare, the light curve of H ii 1100 shows a feature with a profile suggestive of a total occultation of the flaring loop. Eclipse by a substellar companion in a close orbit is possible but would seem an extraordinarily fortuitous event; absorption by a fast-moving cloud of cool material requires NH at least two orders of magnitude greater than any solar or stellar prominence. An occultation may have been mimicked by the coincidence of two flares, though the first, with its decay time being shorter than its rise time and suggestive of , would be unusual. Spectral modelling of the quasi-steady emission shows a rising trend in coronal temperature from F and slowly rotating G stars to K stars to fast-rotating G stars, and a preference for low coronal metallicity. These features are consistent with those of nearby solar-like stars, although none of the three stars showing ‘saturated' emission bears the significant component at 2 keV seen in the saturated coronae of AB Dor and 47 Cas. Of five intermediate-type stars, two are undetected (LX < 4 × 1027erg s−1) and three show X-ray emission with a spectrum and LX consistent with origin from an active solar-like companion

At fast rotation rates, the coronal activity of G- and K-type stars has been observed to ‘saturate' and then decline again at even faster rotation rates - a phenomenon dubbed ‘supersaturation'. In this paper, we investigate coronal activity in fast-rotating M-dwarfs using deep XMM-Newton observations of 97 low-mass stars of known rotation period in the young open cluster NGC 2547 and combine these with published X-ray surveys of low-mass field and cluster stars of known rotation period. Like G- and K-dwarfs, we find that M-dwarfs exhibit increasing coronal activity with decreasing Rossby number NR, the ratio of period to convective turnover time, and that activity saturates at LX/Lbol≃ 10−3 for log NR < −0.8. However, supersaturation is not convincingly displayed by M-dwarfs, despite the presence of many objects in our sample with log NR < −1.8, where supersaturation is observed to occur in higher mass stars. Instead, it appears that a short rotation period is the primary predictor of supersaturation; P ≤ 0.3 d for K-dwarfs and perhaps P ≤ 0.2 d for M-dwarfs. These observations favour the ‘centrifugal stripping' model for supersaturation, where coronal structures are forced open or become radiatively unstable as the Keplerian corotation radius moves inside the X-ray-emitting coronal volume

We report on XMM—Newton observations of the young open cluster NGC 2547 which allow us to characterize coronal activity in solar-type stars, and stars of lower mass, at an age of 30 Myr. X-ray emission is seen from stars at all spectral types, peaking among G stars at luminosities (0.3-3 keV) of Lx≃ 1030.5 erg s−1 and declining to Lx≤ 1029.0 erg s−1 among M stars with masses ≥0.2 M⊙. Coronal spectra show evidence for multi-temperature differential emission measures and low coronal metal abundances of Z≃ 0.3. The G- and K-type stars of NGC 2547 follow the same relationship between X-ray activity and Rossby number established in older clusters and field stars, although most of the solar-type stars in NGC 2547 exhibit saturated or even supersaturated X-ray activity levels. The median levels of Lx and Lx/Lbol in the solar-type stars of NGC 2547 are very similar to those in T-Tauri stars of the Orion Nebula cluster (ONC), but an order of magnitude higher than in the older Pleiades. The spread in X-ray activity levels among solar-type stars in NGC 2547 is much smaller than in older or younger clusters. Coronal temperatures increase with Lx, Lx/Lbol and surface X-ray flux. The most active solar-type stars in NGC 2547 have coronal temperatures intermediate between those in the ONC and the most active older zero-age main-sequence (ZAMS) stars. We show that simple scaling arguments predict higher coronal temperature in coronally saturated stars with lower gravities. A number of candidate flares were identified among the low-mass members and a flaring rate [for total flare energies (0.3-3 keV) > 1034 erg] of one every 350+350−120 ks was found for solar-type stars, which is similar to rates found in the ONC and Pleiades. Comparison with ROSAT High Resolution Imager (HRI) data taken 7 yr earlier reveals that only 10-15 per cent of solar-type stars or stars with Lx > 3 × 1029 erg s−1 exhibit X-ray variability by more than a factor of 2. This is comparable with clusters of similar

The determination of galaxy redshifts in the James Webb Space Telescope's (JWST) blank-field surveys will mostly rely on photometric estimates, based on the data provided by JWST's Near-Infrared Camera (NIRCam) at 0.6–5.0 μm and Mid Infrared Instrument (MIRI) at λ 5.0 μm. In this work we analyze the impact of choosing different combinations of NIRCam and MIRI broadband filters (F070W to F770W), as well as having ancillary data at λ 0.6 μm, on the derived photometric redshifts (z phot) of a total of 5921 real and simulated galaxies, with known input redshifts z = 0–10.

The determination of galaxy redshifts in James Webb Space Telescope (JWST)'s blank-field surveys will mostly rely on photometric estimates, based on the data provided by JWST's Near-Infrared Camera (NIRCam) at 0.6-5.0 {\mu}m and Mid Infrared Instrument (MIRI) at {\lambda}>5.0 {\mu}m. In this work we analyse the impact of choosing different combinations of NIRCam and MIRI broad-band filters (F070W to F770W), as well as having ancillary data at {\lambda}<0.6 {\mu}m, on the derived photometric redshifts (zphot) of a total of 5921 real and simulated galaxies, with known input redshifts z=0-10. We found that observations at {\lambda}<0.6 {\mu}m are necessary to control the contamination of high-z samples by low-z interlopers. Adding MIRI (F560W and F770W) photometry to the NIRCam data mitigates the absence of ancillary observations at {\lambda}<0.6 {\mu}m and improves the redshift estimation. At z=7-10, accurate zphot can be obtained with the NIRCam broad bands alone when S/N>=10, but the zphot quality significantly degrades at S/N<=5. Adding MIRI photometry with one magnitude brighter depth than the NIRCam depth allows for a redshift recovery of 83-99%, depending on SED type, and its effect is particularly noteworthy for galaxies with nebular emission. The vast majority of NIRCam galaxies with [F150W]=29 AB mag at z=7-10 will be detected with MIRI at [F560W, F770W]<28 mag if these sources are at least mildly evolved or have spectra with emission lines boosting the mid-infrared fluxes., Comment: 29 pages, 27 figures, 12 tables. Accepted for publication at the ApJS

[Context]: Thanks to the large collecting area (3 × ∼1500 cm at 1.5 keV) and wide field of view (30′ across in full field mode) of the X-ray cameras on board the European Space Agency X-ray observatory XMM-Newton, each individual pointing can result in the detection of up to several hundred X-ray sources, most of which are newly discovered objects. Since XMM-Newton has now been in orbit for more than 15 yr, hundreds of thousands of sources have been detected. [Aims]: Recently, many improvements in the XMM-Newton data reduction algorithms have been made. These include enhanced source characterisation and reduced spurious source detections, refined astrometric precision of sources, greater net sensitivity for source detection, and the extraction of spectra and time series for fainter sources, both with better signal-to-noise. Thanks to these enhancements, the quality of the catalogue products has been much improved over earlier catalogues. Furthermore, almost 50% more observations are in the public domain compared to 2XMMi-DR3, allowing the XMM-Newton Survey Science Centre to produce a much larger and better quality X-ray source catalogue. [Methods]: The XMM-Newton Survey Science Centre has developed a pipeline to reduce the XMM-Newton data automatically. Using the latest version of this pipeline, along with better calibration, a new version of the catalogue has been produced, using XMM-Newton X-ray observations made public on or before 2013 December 31. Manual screening of all of the X-ray detections ensures the highest data quality. This catalogue is known as 3XMM. [Results]: In the latest release of the 3XMM catalogue, 3XMM-DR5, there are 565 962 X-ray detections comprising 396 910 unique X-ray sources. Spectra and lightcurves are provided for the 133 000 brightest sources. For all detections, the positions on the sky, a measure of the quality of the detection, and an evaluation of the X-ray variability is provided, along with the fluxes and count rates in 7 X-ray

The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28.5 microns. MIRI has, within a single 'package', four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R ~ 100) spectroscopy, and medium-resolving power (R ~ 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of < 6.7 K. This paper describes the driving principles behind the design of MIRI, the primary design parameters, and their realization in terms of the 'as-built' instrument. It also describes the test program that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements.

The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products provide an excellent basis for a comprehensive and sensitive survey of stellar flares - both from targeted active stars and from those observed serendipitously in the half-degree diameter field-of-view of each observation. The 2XMM Catalogue and the associated time-series (`light-curve') data products have been used as the basis for a survey of X-ray flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray light-curves. Where available, we have compared XMM OM UV/optical data with the X-ray light-curves. Our sample contains ~130 flares with well-observed profiles; they originate from ~70 stars. The flares range in duration from ~1e3 to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to ~1e35 erg. Most of the ~30 serendipitously-observed stars have little previously reported information. The hardness-ratio plots clearly illustrate the spectral (and hence inferred temperature) variations characteristic of many flares, and provide an easily accessible overview of the data. We present flare frequency distributions from both target and serendipitous observations. The latter provide an unbiased (with respect to stellar activity) study of flare energetics; in addition, they allow us to predict numbers of stellar flares that may be detected in future X-ray wide-field surveys. The serendipitous sample demonstrates the need for care when calculating flaring rates., Comment: 26 pages, 24 figures. Additional tables and figures available as 4 ancillary files. To be published in Astronomy and Astrophysics

Thanks to the large collecting area (3 x ~1500 cm$^2$ at 1.5 keV) and wide field of view (30' across in full field mode) of the X-ray cameras on board the European Space Agency X-ray observatory XMM-Newton, each individual pointing can result in the detection of hundreds of X-ray sources, most of which are newly discovered. Recently, many improvements in the XMM-Newton data reduction algorithms have been made. These include enhanced source characterisation and reduced spurious source detections, refined astrometric precision, greater net sensitivity and the extraction of spectra and time series for fainter sources, with better signal-to-noise. Further, almost 50\% more observations are in the public domain compared to 2XMMi-DR3, allowing the XMM-Newton Survey Science Centre (XMM-SSC) to produce a much larger and better quality X-ray source catalogue. The XMM-SSC has developed a pipeline to reduce the XMM-Newton data automatically and using improved calibration a new catalogue version has been produced from XMM-Newton data made public by 2013 Dec. 31 (13 years of data). Manual screening ensures the highest data quality. This catalogue is known as 3XMM. In the latest release, 3XMM-DR5, there are 565962 X-ray detections comprising 396910 unique X-ray sources. For the 133000 brightest sources, spectra and lightcurves are provided. For all detections, the positions on the sky, a measure of the quality of the detection, and an evaluation of the X-ray variability is provided, along with the fluxes and count rates in 7 X-ray energy bands, the total 0.2-12 keV band counts, and four hardness ratios. To identify the detections, a cross correlation with 228 catalogues is also provided for each X-ray detection. 3XMM-DR5 is the largest X-ray source catalogue ever produced. Thanks to the large array of data products, it is an excellent resource in which to find new and extreme objects., Comment: 23 pages, version accepted for publication in A&A

The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28: 5 mu m. MIRI has, within a single package, four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R similar to 100) spectroscopy, and medium-resolving power (R similar to 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of <6.7 K. This paper describes the driving principles behind the design of MIRI, the primary design parameters, and their realization in terms of the as-built instrument. It also describes the test program that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements.

The 3XMM-DR4 catalogue is the third generation catalogue of serendipitous X-ray sources from the European Space Agency's (ESA) XMM-Newton observatory, and has been created by the XMM-Newton Survey Science Centre (SSC) on behalf of ESA. Released in July 2013, 3XMM-DR4 contains 531261 detections from 372728 unique sources observed in 7427 XMM-Newton observations, about 50% more than in the preceding 2XMMi-DR3 catalogue, made public in April 2010. We review some of the key science-driven algorithmic and calibration changes to the processing pipeline adopted to enhance the scientific quality of the catalogue, such as the optimised filtering of background flares, improvements to the astrometric analysis and upgrades to the catalogue construction process. Examples of the gains obtained are illustrated.

The majority of active galactic nuclei (AGN) are obscured by large amounts of absorbing material that makes them invisible at many wavelengths. X-rays, given their penetrating power, provide the most secure way for finding these AGN. The XMM-Newton serendipitous source catalog is the largest catalog of X-ray sources ever produced; it contains about half a million detections. These sources are mostly AGN. We have derived X-ray spectral fits for very many 3XMM-DR4 sources ($\gtrsim$ 114 000 observations, corresponding to $\sim$ 77 000 unique sources), which contain more than 50 source photons per detector. Here, we use a subsample of $\simeq$ 1000 AGN in the footprint of the SDSS area (covering 120 deg$^2$) with available spectroscopic redshifts. We searched for highly obscured AGN by applying an automated selection technique based on X-ray spectral analysis that is capable of efficiently selecting AGN. The selection is based on the presence of either a) flat rest-frame spectra; b) flat observed spectra; c) an absorption turnover, indicative of a high rest-frame column density; or d) an Fe K$\alpha$ line with an equivalent width > 500 eV. We found 81 highly obscured candidate sources. Subsequent detailed manual spectral fits revealed that 28 of them are heavily absorbed by column densities higher than 10$^{23}$ cm$^{-2}$. Of these 28 AGN, 15 are candidate Compton-thick AGN on the basis of either a high column density, consistent within the 90% confidence level with N$_{\rm H}$ $>$10$^{24}$ cm$^{-2}$, or a large equivalent width (>500 eV) of the Fe K$\alpha$ line. Another six are associated with near-Compton-thick AGN with column densities of $\sim$ 5$\times$10$^{23}$ cm$^{-2}$. A combination of selection criteria a) and c) for low-quality spectra, and a) and d) for medium- to high-quality spectra, pinpoint highly absorbed AGN with an efficiency of 80%., Comment: 18 pages, 10 figures, accepted for publication in A&A

Many different classes of X-ray sources contribute to the Galactic landscape at high energies. Although the nature of the most luminous X-ray emitters is now fairly well understood, the population of low-to-medium X-ray luminosity (Lx = 10^27-10^34 erg/s) sources remains much less studied, our knowledge being mostly based on the observation of local members. The advent of wide field and high sensitivity X-ray telescopes such as XMM-Newton now offers the opportunity to observe this low-to-medium Lx population at large distances. We report on the results of a Galactic plane survey conducted by the XMM-Newton Survey Science Centre (SSC). Beyond its astrophysical goals, this survey aims at gathering a representative sample of identified X-ray sources at low latitude that can be used later on to statistically identify the rest of the serendipitous sources discovered in the Milky Way. The survey is based on 26 XMM-Newton observations, obtained at |b| < 20 deg, distributed over a large range in Galactic longitudes and covering a summed area of 4 deg2. The flux limit of our survey is 2 x 10-15 erg/cm^2/s in the soft (0.5 - 2 keV) band and 1 x 10^-14 erg/cm^2/s in the hard (2 - 12 keV) band. We detect a total of 1319 individual X-ray sources. Using optical follow-up observations supplemented by cross-correlation with a large range of multi-wavelength archival catalogues we identify 316 X-ray sources. This constitutes the largest group of spectroscopically identified low latitude X-ray sources at this flux level. The majority of the identified X-ray sources are active coronae with spectral types in the range A - M at maximum distances of ~ 1 kpc. The number of identified active stars increases towards late spectral types, reaching a maximum at K. (abridged), Comment: Accepted for publication in A&A

Many different classes of X-ray sources contribute to the Galactic landscape at high energies. Although the nature of the most luminous X-ray emitters is now fairly well understood, the population of low-to-medium X-ray luminosity (LX = 1027-34 erg s-1) sources remains much less studied, our knowledge being mostly based on the observation of local members. The advent of wide field and high sensitivity X-ray telescopes such as XMM-Newton now offers the opportunity to observe this low-to-medium LX population at large distances. We report on the results of a Galactic plane survey conducted by the XMM-Newton Survey Science Centre (SSC). Beyond its astrophysical goals, this survey aims at gathering a representative sample of identified X-ray sources at low latitude that can be used later on to statistically identify the rest of the serendipitous sources discovered in the Milky Way. The survey is based on 26 XMM-Newton observations, obtained at | b | < 20 deg, distributed over a large range in Galactic longitudes and covering a summed area of 4 deg2. The flux limit of our survey is 2 × 10-15 erg cm-2 s-1 in the soft (0.5-2 keV) band and 1 × 10-14 erg cm-2 s-1 in the hard (2-12 keV) band. We detect a total of 1319 individual X-ray sources. Using optical follow-up observations supplemented by cross-correlation with a large range of multi-wavelength archival catalogues we identify 316 X-ray sources. This constitutes the largest group of spectroscopically identified low latitude X-ray sources at this flux level. The majority of the identified X-ray sources are active coronae with spectral types in the range A-M at maximum distances of ~1 kpc. The number of identified active starsincreases towards late spectral types, reaching a maximum at K. Using infrared colours we classify 18% of the stars as giants. The observed distributions of FX/FV, X-ray and infrared colours indicates that our sample is dominated by a young (100 Myr) to intermediate (600 Myr) age population with a sma

Context. EECep is an unusual long-period (5.6 yr) eclipsing binary discovered during the mid-twentieth century. It undergoes almost-grey eclipses that vary in terms of both depth and duration at different epochs. The system consists of a Be type star and a dark dusty disk around an invisible companion. EECep together with the widely studied epsilon Aur are the only two known cases of long-period eclipsing binaries with a dark, dusty disk component responsible for periodic obscurations. Aims. Two observational campaigns were carried out during the eclipses of EECep in 2003 and 2008/9 to verify whether the eclipsing body in the system is indeed a dark disk and to understand the observed changes in the depths and durations of the eclipses. Methods. Multicolour photometric data and spectroscopic observations performed at both low and high resolutions were collected with several dozen instruments located in Europe and North America. We numerically modelled the variations in brightness and colour during the eclipses. We tested models with different disk structure, taking into consideration the inhomogeneous surface brightness of the Be star. We considered the possibility of disk precession. Results. The complete set of observational data collected during the last three eclipses are made available to the astronomical community. The 2003 and 2008/9 eclipses of EECep were very shallow. The latter is the shallowest among all observed. The very high quality photometric data illustrate in detail the colour evolution during the eclipses for the first time. Two blue maxima in the colour indices were detected during these two eclipses, one before and one after the photometric minimum. The first (stronger) blue maximum is simultaneous with a "bump" that is very clear in all the UBV(RI)(C) light curves. A temporary increase in the I-band brightness at the orbital phase similar to 0.2 was observed after each of the last three eclipses. Variations in the spectral line profiles seem to

This summary reports on papers presented at the Cool Stars-16 meeting in the splinter session "Solar and Stellar flares." Although many topics were discussed, the main themes were the commonality of interests, and of physics, between the solar and stellar flare communities, and the opportunities for important new observations in the near future., Comment: 11 pages, 2 figures

At fast rotation rates the coronal activity of G- and K-type stars has been observed to "saturate" and then decline again at even faster rotation rates -- a phenomenon dubbed "super-saturation". In this paper we investigate coronal activity in fast-rotating M-dwarfs using deep XMM-Newton observations of 97 low-mass stars of known rotation period in the young open cluster NGC 2547, and combine these with published X-ray surveys of low-mass field and cluster stars of known rotation period. Like G- and K-dwarfs, we find that M-dwarfs exhibit increasing coronal activity with decreasing Rossby number N_R, the ratio of period to convective turnover time, and that activity saturates at L_x/L_bol ~ 10^-3 for log N_R < -0.8. However, super-saturation is not convincingly displayed by M-dwarfs, despite the presence of many objects in our sample with log N_R < -1.8, where super-saturation is observed to occur in higher mass stars. Instead, it appears that a short rotation period is the primary predictor of super-saturation; P <=0.3d for K-dwarfs and perhaps P <=0.2d for M-dwarfs. These observations favour the "centrifugal stripping" model for super-saturation, where coronal structures are forced open or become radiatively unstable as the Keplerian co-rotation radius moves inside the X-ray emitting coronal volume., Comment: Accepted for Monthly Notices of the Royal Astronomical Society. 15 pages, 7 figures (electronic tables from the author)

The photometric and spectroscopic observational campaign organized for the 2008/9 eclipse of EE Cep revealed features, which indicate that the eclipsing disk in the EE Cep system has a multi-ring structure. We suggest that the gaps in the disk can be related to the possible planet formation., Comment: 6 pages, 6 figures, contribution to the conference proceedings: Binaries - Key to Comprehension of the Universe, Brno, Czech Republic, 8-12 Jul. 2009

[Aims]: Pointed observations with XMM-Newton provide the basis for creating catalogues of X-ray sources detected serendipitously in each field. This paper describes the creation and characteristics of the 2XMM catalogue. [Methods]: The 2XMM catalogue has been compiled from a new processing of the XMM-Newton EPIC camera data. The main features of the processing pipeline are described in detail. [Results]: The catalogue, the largest ever made at X-ray wavelengths, contains 246 897 detections drawn from 3491 public XMM-Newton observations over a 7-year interval, which relate to 191 870 unique sources. The catalogue fields cover a sky area of more than 500 deg2. The non-overlapping sky area is ∼360 deg2 (∼1% of the sky) as many regions of the sky are observed more than once by XMM-Newton. The catalogue probes a large sky area at the flux limit where the bulk of the objects that contribute to the X-ray background lie and provides a major resource for generating large, well-defined X-ray selected source samples, studying the X-ray source population and identifying rare object types. The main characteristics of the catalogue are presented, including its photometric and astrometric properties.

Aims: Pointed observations with XMM-Newton provide the basis for creating catalogues of X-ray sources detected serendipitously in each field. This paper describes the creation and characteristics of the 2XMM catalogue. Methods: The 2XMM catalogue has been compiled from a new processing of the XMM-Newton EPIC camera data. The main features of the processing pipeline are described in detail. Results: The catalogue, the largest ever made at X-ray wavelengths, contains 246,897 detections drawn from 3491 public XMM-Newton observations over a 7-year interval, which relate to 191,870 unique sources. The catalogue fields cover a sky area of more than 500 sq.deg. The non-overlapping sky area is ~360 sq.deg. (~1% of the sky) as many regions of the sky are observed more than once by XMM-Newton. The catalogue probes a large sky area at the flux limit where the bulk of the objects that contribute to the X-ray background lie and provides a major resource for generating large, well-defined X-ray selected source samples, studying the X-ray source population and identifying rare object types. The main characteristics of the catalogue are presented, including its photometric and astrometric properties ., Comment: 27 pages (plus 8 pages appendices), 15 figures. Minor changes following referee's comments; now accepted for publication in A & A. Note that this paper "V", not paper "VI" in the series. Previous posting was incorrect in this regard

We present the XMM-Newton Medium sensitivity Survey (XMS), including a total of 318 X-ray sources found among the serendipitous content of 25 XMM-Newton target fields. The XMS comprises four largely overlapping source samples selected at soft (0.5-2 keV), intermediate (0.5-4.5 keV), hard (2-10 keV) and ultra-hard (4.5-7.5 keV) bands, the first three of them being flux-limited. We report on the optical identification of the XMS samples, complete to 85-95%. At the intermediate flux levels sampled by the XMS we find that the X-ray sky is largely dominated by Active Galactic Nuclei. The fraction of stars in soft X-ray selected samples is below 10%, and only a few per cent for hard selected samples. We find that the fraction of optically obscured objects in the AGN population stays constant at around 15-20% for soft and intermediate band selected X-ray sources, over 2 decades of flux. The fraction of obscured objects amongst the AGN population is larger (~35-45%) in the hard or ultra-hard selected samples, and constant across a similarly wide flux range. The distribution in X-ray-to-optical flux ratio is a strong function of the selection band, with a larger fraction of sources with high values in hard selected samples. Sources with X-ray-to-optical flux ratios in excess of 10 are dominated by obscured AGN, but with a significant contribution from unobscured AGN., Comment: A&A, accepted

[Aims] X-ray sources at intermediate fluxes (a few x 10-14 erg cm-2 s-1) with a sky density of ~100 deg-2 are responsible for a significant fraction of the cosmic X-ray background at various energies below 10 keV. The aim of this paper is to provide an unbiased and quantitative description of the X-ray source population at these fluxes and in various X-ray energy bands., [Methods] We present the XMM-Newton Medium sensitivity Survey (XMS), including a total of 318 X-ray sources found among the serendipitous content of 25 XMM-Newton target fields. The XMS comprises four largely overlapping source samples selected at soft (0.5-2 keV), intermediate (0.5-4.5 keV), hard (2-10 keV) and ultra-hard (4.5-7.5 keV) bands, the first three of them being flux-limited., [Results] We report on the optical identification of the XMS samples, complete to 85-95%. At the flux levels sampled by the XMS we find that the X-ray sky is largely dominated by Active Galactic Nuclei. The fraction of stars in soft X-ray selected samples is below 10%, and only a few per cent for hard selected samples. We find that the fraction of optically obscured objects in the AGN population stays constant at around 15-20% for soft and intermediate band selected X-ray sources, over 2 decades of flux. The fraction of obscured objects amongst the AGN population is larger (~35-45%) in the hard or ultra-hard selected samples, and constant across a similarly wide flux range. The distribution in X-ray-to-optical flux ratio is a strong function of the selection band, with a larger fraction of sources with high values in hard selected samples. Sources with X-ray-to-optical flux ratios in excess of 10 are dominated by obscured AGN, but with a significant contribution from unobscured AGN.

We report XMM-Newton observations of the young open cluster NGC 2547 which allow us to characterise coronal activity in solar-type stars at an age of 30 Myr. X-ray emission peaks among G-stars at luminosities (0.3-3keV) of Lx~10^{30.5} erg/s and declines to Lx<=10^{29.0} erg/s among M-stars. Coronal spectra show evidence for multi-temperature differential emission measures and low coronal metal abundances (Z~0.3). The G- and K-type stars follow the same relationship between X-ray activity and Rossby number established in older clusters and field stars, although most solar-type stars in NGC 2547 exhibit saturated/super-saturated X-ray activity levels. Median levels of Lx and Lx/Lbol in the solar-type stars of NGC 2547 are similar to T-Tauri stars of the Orion Nebula cluster (ONC), but an order of magnitude higher than in the older Pleiades. The spread in X-ray activity levels among solar-type stars in NGC 2547 is much smaller than in older or younger clusters. Coronal temperatures increase with Lx, Lx/Lbol and surface X-ray flux. Active solar-type stars in NGC 2547 have coronal temperatures between those in the ONC and the most active older ZAMS stars. A flaring rate (for total flare energies [0.3-3keV] >10^{34} erg) of 1 every 350^{+350}_{-120} ks was found for solar-type stars, similar to rates found in the ONC and Pleiades. Comparison with ROSAT HRI data taken 7 years previously reveals that only 10-15 percent of solar-type stars or stars with Lx>3x10^{29} erg/s exhibit X-ray variability by more than a factor of two. The similar levels of X-ray activity and rate of occurrence for large flares in NGC 2547 and the ONC demonstrate that the X-ray radiation environment around young solar-type stars remains relatively constant over their first 30 Myr (abridged)., Comment: Accepted for publication in MNRAS. Electronic tables available from the author

We report the first detection of X-ray emission from a brown dwarf in the Pleiades, the M7-type Roque 14, obtained using the EPIC detectors on XMM-Newton. This is the first X-ray detection of a brown dwarf intermediate in age between ~12 and ~320 Myr. The emission appears persistent, although we cannot rule out flare-like behaviour with a decay time-scale > 4 ks. The time-averaged X-ray luminosity of Lx = (3.3 +/- 0.8) x 10^{27} erg/s, and its ratios with the bolometric (Lx/Lbol = 10^{-3.05}) and Halpha (Lx/LHa = 4.0) luminosities suggest magnetic activity similar to that of active main-sequence M dwarfs, such as the M7 old-disc star VB 8, though the suspected binary nature of Roque 14 merits further attention. No emission is detected from four proposed later-type Pleiades brown dwarfs, with upper limits to Lx in the range 2.1-3.8 x 10^{27} erg/s and to log(Lx/Lbol) in the range -3.10 to -2.91., Comment: 8 pages, 4 figures (6 eps files), accepted for publication in MNRAS, Na I "emission" corrected to "absorption" in description of targets

We perform X-ray spectral and timing analyses of solar-like (spectral types F5--K8) and intermediate-type (B4--F4) Pleiads observed in a 40-ks XMM-Newton EPIC exposure. All 8 solar-like members have ``quasi-steady'' \lx $\ga 10^{29}$ erg/s and 4 exhibit flares. Using a hydrodynamic modelling technique we derive loop half-lengths ${\cal L} \la 0.5 R_{\star}$ for the two strongest flares, on HII 1032 and HII 1100. HII 1100's lightcurve suggests a total occultation of the flaring loop. Eclipse by a substellar companion in a close orbit is possible but would seem a highly fortuitous event; absorption by a fast-moving cloud of cool material requires \nh at least two orders of magnitude greater than any solar or stellar prominence. An occultation may have been mimicked by the coincidence of two flares, though the first, its decay time shorter than its rise time and suggestive of ${\cal L} \sim 0.02 R_{\star}$, would be unusual. Spectral modelling of the quasi-steady emission shows a rising trend in coronal temperature from F and slowly-rotating G stars through K stars to fast-rotating G stars, and a preference for low coronal metallicity: features consistent with those of nearby solar-like stars, although none of the three stars showing ``saturated'' emission bears the significant component at 2 keV seen in the saturated coronae of AB Dor and 47 Cas. Of 5 intermediate-type stars, 2 are undetected (\lx$ < 4 \times 10^{27}$ erg/s) and 3 show X-ray emission with a spectrum and \lx consistent with origin from an active solar-like companion., Comment: 14 pages, 7 figs (29 eps files), accepted for publication in MNRAS

We describe the production, properties and scientific potential of the XMM-Newton catalogue of serendipitous X-ray sources. The first version of this catalogue is nearing completion and is planned to be released before the end of 2002., Comment: Proceedings of the "X-ray surveys, in the light of the new observatories" workshop, Astronomische Nachrichten, in the press (4 pages, 3 eps figures, uses an.cls)

This paper describes the performance of XMM-Newton for serendipitous surveys and summarises the scope and potential of the XMM-Newton Serendipitous Survey. The role of the Survey Science Centre (SSC) in the XMM-Newton project is outlined. The SCC's follow-up and identification programme for the XMM-Newton serendipitous survey is described together with the presentation of some of the first results.