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International audience; Combining experimental set up and ab initio molecular dynamics simulations, we were able to follow the time evolution of the X-ray absorption near edge spectrum (XANES) of a dense copper plasma. This provides a deep insight into femtosecond laser interaction with a metallic copper target. This paper presents a review of the experimental developments we made to reduce the X-ray probe duration, from approximately 10 ps to fs duration with table-top laser systems. Moreover, we present microscopic scale simulations, performed with Density Functional Theory, as well as macroscopic simulations considering the Two-Temperature Model. These tools allow us to get a complete picture of the evolution of the target at a microscopic level, from the heating process to the melting and expansion stages, with a clear view of the physics involved during these processes. This article is part of the theme issue ‘Dynamic and transient processes in warm dense matter’.

Mechanisms of particle heating are crucial to understanding the shock physics in supernova remnants (SNRs). However, there has been little information on time variabilities of thermalized particles so far. Here, we present a discovery of a gradually-brightening thermal X-ray emission found in Chandra data of Tycho's SNR obtained during 2000--2015. The emission exhibits a knot-like feature (Knot1) with a diameter of $\simeq0.04$~pc located in the northwestern limb, where we also find localized H$\alpha$ filaments in an optical image taken with the Hubble Space Telescope in 2008. The model with the solar abundance reproduces the spectra of Knot1, suggesting that Knot1 originates from interstellar medium; this is the first detection of thermal X-ray emission from swept-up gas found in Tycho's SNR. Our spectral analysis indicates that the electron temperature of Knot1 has increased from $\sim0.30$ keV to $\sim0.69$ keV within the period between 2000 and 2015. These results lead us to ascribe the time-variable emission to a small dense clump recently heated by the forward shock at the location of Knot1. The electron-to-proton temperature ratio immediately downstream the shock ($\beta_{0}\equiv T_e/T_p$) is constrained to be $m_e/m_p\leq\beta_{0}\leq0.15$ to reproduce the data, indicating the collisionless electron heating with efficiency consistent with previous H$\alpha$ observations of Tycho and other SNRs with high shock velocities., Comment: 13 pages, 12 figures, accepted for publication in ApJ

Inertial Confinement Fusion (ICF) is a subject that has been studied for decades, because of its potential for clean energy generation. Although thermonuclear fusion has been achieved, the energy out has always been considerably less than the energy in, so high energy gain with a burning thermonuclear plasma is still some way off. A multitude of new science has come from the ICF programme that is relevant outside the field (typically in astrophysics). What we look at in this text is what new science can come from the much more extreme conditions that would be created in the laboratory if a burning ICF plasma could be created -- in terms of energy density the most extreme macroscopic environment ever created. We show that this could impact science from particle physics through astrophysics and on to cosmology. We also believe that the experiments that we propose here are only a small part of the science that will be opened up when a burning thermonuclear plasma is created in the laboratory.

Galactic supernova remnants (SNRs) and their environments provide the nearest laboratories to study SN feedback. We performed molecular observations toward SNR W49B, the most luminous Galactic SNR in the X-ray band, aiming to explore signs of multiple feedback channels of SNRs on nearby molecular clouds (MCs). We found very broad HCO+ lines with widths of dv = 48--75 km/s in the SNR southwest, providing strong evidence that W49B is perturbing MCs at a systemic velocity of $V_{LSR}=61$--65 km/s, and placing W49B at a distance of $7.9\pm 0.6$ kpc. We observed unusually high-intensity ratios of HCO+ J=1-0/CO J=1-0 not only at shocked regions ($1.1\pm 0.4$ and $0.70\pm 0.16$), but also in quiescent clouds over 1 pc away from the SNR's eastern boundary (> 0.2). By comparing with the magnetohydrodynamics shock models, we interpret that the high ratio in the broad-line regions can result from a cosmic-ray (CR) induced chemistry in shocked MCs, where the CR ionization rate is enhanced to around 10--100 times of the Galactic level. The high HCO+/CO ratio outside the SNR is probably caused by the radiation precursor, while the luminous X-ray emission of W49B can explain a few properties in this region. The above results provide observational evidence that SNRs can strongly influence the molecular chemistry in and outside the shock boundary via their shocks, CRs, and radiation. We propose that the HCO+/CO ratio is a potentially useful tool to probe an SNR's multichannel influence on MCs., 19 pages, 11 figures, ApJ in press

Since the day of its explosion, supernova (SN) 1987A has been closely monitored to study its evolution and to detect its central compact relic. In fact, the formation of a neutron star is strongly supported by the detection of neutrinos from the SN. However, besides the detection in the Atacama Large Millimeter/submillimeter Array (ALMA) data of a feature that is compatible with the emission arising from a proto-pulsar wind nebula (PWN), the only hint for the existence of such elusive compact object is provided by the detection of hard emission in NuSTAR data up to ~ 20 keV. We report on the simultaneous analysis of multi-epoch observations of SN 1987A performed with Chandra, XMM-Newton and NuSTAR. We also compare the observations with a state-of-the-art 3D magnetohydrodynamic (MHD) simulation of SN 1987A. A heavily absorbed power-law, consistent with the emission from a PWN embedded in the heart of SN 1987A, is needed to properly describe the high-energy part of the observed spectra. The spectral parameters of the best-fit power-law are in agreement with the previous estimate, and exclude diffusive shock acceleration as a possible mechanism responsible for the observed non-thermal emission. The information extracted from our analysis are used to infer the physical characteristics of the pulsar and the broad-band emission of its nebula, in agreement with the ALMA data. Analysis of the synthetic spectra also show that, in the near future, the main contribution to Fe K emission line will originate in the outermost shocked ejecta of SN 1987A., Accepted for publication in ApJ

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., We present the analysis of archival XMM-Newton European Photon Imaging Camera (EPIC) X-ray observations of the symbiotic star R Aquarii. We used the Extended Source Analysis Software package to disclose diffuse soft X-ray emission extending up to 2farcm2 (≈0.27 pc) from this binary system. The depth of these XMM-Newton EPIC observations reveals in unprecedented detail the spatial distribution of this diffuse emission, with a bipolar morphology spatially correlated with the optical nebula. The extended X-ray emission shares the same dominant soft X-ray-emitting temperature as the clumps in the jet-like feature resolved by Chandra in the vicinity of the binary system. The harder component in the jet might suggest that the gas cools down; however, the possible presence of nonthermal emission produced by the presence of a magnetic field collimating the mass ejection cannot be discarded. We propose that the ongoing precessing jet creates bipolar cavities filled with X-ray-emitting hot gas that feeds the more extended X-ray bubble as they get disrupted. These EPIC observations demonstrate that the jet feedback mechanism produced by an accreting disk around an evolved, low-mass star can blow hot bubbles, similar to those produced by jets arising from the nuclei of active galaxies. © 2022. The Author(s). Published by the American Astronomical Society., J.A.T. acknowledges support by the Fundación Marcos Moshinsky (Mexico) and UNAM PAPIIT project IA101622 (Mexico). L.S. acknowledges support by UNAM PAPIIT project IN110122 (Mexico). M.A.G. acknowledges the support of grant PGC 2018-102184-B-I00 of the Ministerio de Educación, Innovación y Universidades cofunded with FEDER funds. G.R.-L. acknowledges support from CONACyT grant 263373. Y.H.C. acknowledges the grant MOST 110-2112-M-001-020 from the Ministry of Science and Technology (Taiwan). Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research has made use of data obtained from the Chandra Data Archive and software provided by the Chandra X-ray Center (CXC) in the application package CIAO. This work has made extensive use of NASA's Astrophysics Data System., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

We present an analysis of the optical properties of three Ultra Luminous X-ray (ULX) sources identified in NGC 925. We use Integral field unit data from the George Mitchel spectrograph in the context of the Metal-THINGS survey. The optical properties for ULX-1 and ULX-3 are presented, while the spaxel associated with ULX-2 had a low S/N, which prevented its analysis. We also report the kinematics and dimensions of the optical nebula associated with each ULX using ancillary data from the PUMA Fabry-Perot spectrograph. A BPT analysis demonstrates that most spaxels in NGC 925 are dominated by star-forming regions, including those associated with ULX-1 and ULX-3. Using the resolved gas-phase metallicities, a negative metallicity gradient is found, consistent with previous results for spiral galaxies, while the ionization parameter tends to increase radially throughout the galaxy. Interestingly, ULX-1 shows a very low gas metallicity for its galactocentric distance, identified by two independent methods, while exhibiting a typical ionization. We find that such low gas metallicity is best explained in the context of the high-mass X-ray binary population, where the low-metallicity environment favours active Roche lobe overflows that can drive much higher accretion rates. An alternative scenario invoking accretion of a low-mass galaxy is not supported by the data in this region. Finally, ULX-3 shows both a high metallicity and ionization parameter, which is consistent with the progenitor being a highly-accreting neutron star within an evolved stellar population region., Comment: Accepted by ApJ

The proposed THESEUS mission will vastly expand the capabilities to monitor the high-energy sky, and will exploit large samples of gamma-ray bursts to probe the early Universe back to the first generation of stars, and to advance multi-messenger astrophysics by detecting and localizing the counterparts of gravitational waves and cosmic neutrino sources. The combination and coordination of these activities with multi-wavelength, multi-messenger facilities expected to be operating in the thirties will open new avenues of exploration in many areas of astrophysics, cosmology and fundamental physics, thus adding considerable strength to the overall scientific impact of THESEUS and these facilities. We discuss here a number of these powerful synergies., Revised version after submission to Experimental Astronomy

Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be able to detect and characterize, discussing detection rate expectations and scientific impact., Submitted to Experimental Astronomy

Since the day of its explosion, SN 1987A (SN87A) was closely monitored with the aim to study its evolution and to detect its central compact relic. The detection of neutrinos from the supernova strongly supports the formation of a neutron star (NS). However, the constant and fruitless search for this object has led to different hypotheses on its nature. Up to date, the detection in the ALMA data of a feature somehow compatible with the emission arising from a proto Pulsar Wind Nebula (PWN) is the only hint of the existence of such elusive compact object. Here we tackle this 33-years old issue by analyzing archived observations of SN87A performed Chandra and NuSTAR in different years. We firmly detect nonthermal emission in the $10-20$ kev energy band, due to synchrotron radiation. The possible physical mechanism powering such emission is twofold: diffusive shock acceleration (DSA) or emission arising from an absorbed PWN. By relating a state-of-the-art magneto-hydrodynamic simulation of SN87A to the actual data, we reconstruct the absorption pattern of the PWN embedded in the remnant and surrounded by cold ejecta. We found that, even though the DSA scenario cannot be firmly excluded, the most likely scenario that well explains the data is the PWN emission., Accepted for publication in ApJ Letters

A fast X-ray focusing polycapillary alignment method was implemented and tested using a compact short-pulse laser-driven broadband X-ray source., A new modification of a table-top laser-driven water-jet plasma X-ray source has been successfully implemented and commissioned at the Extreme Light Infrastructure (ELI) Beamlines user facility. In order to preserve the broadband nature of the source for spectroscopic experiments, a polycapillary lens was initially chosen as the focusing element. Generally, polycapillary X-ray optics have a narrow photon acceptance angle and small field of view, making alignment complicated and time-consuming. This contribution demonstrates a straightforward, reliable and reproducible procedure for aligning polycapillary focusing optics with broadband X-rays. The method involves a pre-alignment step where two X-ray slits are mounted orthogonally on opposite sides of a 3D-printed cylindrical polycapillary holder. This helps to precisely determine the optical axis of the X-ray beam. Subsequent mounting of the polycapillary in the pre-aligned holder with the slits removed allowed for immediate transmission of the X-ray photons through the optics and has provided a good starting point for fine alignment.

The interaction of electrons with strong electromagnetic fields is fundamental to the ability to design high‐quality radiation sources. At the core of all such sources is a tradeoff between compactness and higher output radiation intensities. Conventional photonic devices are limited in size by their operating wavelength, which helps compactness at the cost of a small interaction area. Here, plasmonic modes supported by multilayer graphene metamaterials are shown to provide a larger interaction area with the electron beam, while also tapping into the extreme confinement of graphene plasmons to generate high‐frequency photons with relatively low‐energy electrons available from tabletop sources. For 5 MeV electrons, a metamaterial of 50 layers and length 50 µm, and a beam current of 1.7 µA, it is, for instance, possible to generate X‐rays of intensity 1.5 × 107 photons sr−1 s−1 1%BW, 580 times more than for a single‐layer design. The frequency of the driving laser dynamically tunes the photon emission spectrum. This work demonstrates a unique free‐electron light source, wherein the electron mean free path in a given material is longer than the device length, relaxing the requirements of complex electron beam systems and potentially paving the way to high‐yield, compact, and tunable X‐ray sources., The short operating wavelength of nanophotonic devices is crucial for compactness but also typically limits the interaction area and hence yield. Graphene metamaterials can enormously scale up the interaction area of plasmon‐based free‐electron light sources, paving the way to high‐yield, compact, and tunable sources of extreme ultraviolet to gamma rays.

We analyzed multiwavelength observations of the previously identified Galactic center X-ray binary CXO 174528.79-290942.8 (XID 6592) and determine that the near-infrared counterpart is a red supergiant based on its spectrum and luminosity. Scutum X-1 is the only previously known X-ray binary with a red supergiant donor star and closely resembles XID 6592 in terms of X-ray luminosity (L$_{\mathrm{X}}$), absolute magnitude, and IR variability (L$_{\mathrm{IR,var}}$), supporting the conclusion that XID 6592 contains a red supergiant donor star. The XID 6592 infrared counterpart shows variability of $\sim$0.5 mag in the Wide-field Infrared Survey Explorer-1 band (3.4 $��$m) on timescales of a few hours. Other infrared data sets also show large-amplitude variability from this source at earlier epochs but do not show significant variability in recent data. We do not expect red supergiants to vary by $\sim50\%$ in luminosity over these short timescales, indicating that the variability should be powered by the compact object. However, the X-ray luminosity of this system is typically $\sim1000\times$ less than the variable luminosity in the infrared and falls below the Chandra detection limit. While X-ray reprocessing can produce large-amplitude fast infrared variability, it typically requires L$_{\mathrm{X}} >> $ L$_{\mathrm{IR,var}}$ to do so, indicating that another process must be at work. We suggest that this system may be a supergiant fast X-ray transient (SFXT), and that a large ($\sim10^{38}$ ergs s$^{-1}$), fast ($10^{2-4}$ s) X-ray flare could explain the rapid IR variability and lack of a long-lasting X-ray outburst detection. SFXTs are normally associated with blue supergiant companions, so if confirmed, XID 6592 would be the first red supergiant SFXT, as well as the second X-ray red supergiant binary., 13 pages, 14 figures; published in the Astrophysical Journal

We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, disc-accreting neutron stars by exploiting the occultation of parts of the inner disc by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low mass X-ray binary systems seen under inclinations higher than ~65 degrees. We analyse a NuSTAR observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to ~2{\div}3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods too aim to achieve in the future., Comment: 17 pages, 8 figures; this is a pre-print edition of an article that has been accepted for publication in the Astrophysical Journal

Here we re-analyze the archival {\it Chandra} data for the central parts of the Centaurus\,A radio galaxy, aiming for a systematic investigation of the X-ray emission associated with the inner radio lobes in the system, and their immediate surroundings. In particular, we focus on four distinct features characterized by the soft excess with respect to the adjacent fields. Those include the two regions located at kpc distances from the nucleus to the West and East, the extended bow-shock structure to the South, and a fragment of a thin arc North from the center. The selected North, West, and South features coincide with the edges of the radio lobes, while the East structure is seemingly displaced from the radio-emitting plasma. Our X-ray spectral analysis reveals (i) a power-law emission component with photon index $\Gamma \sim 2$ in the North, East, and South regions, and (ii) a dense (number density $\sim 0.3$\,cm$^{-3}$) and relatively cold (temperature $\sim 0.2$\,keV) gas in the East and West regions. The power-law emission is consistent with the synchrotron continuum generated at the edges of the radio structure, and implies that the efficiency of the electron acceleration at the terminal bow-shock does not vary dramatically over the inner lobes' extension. The presence of gaseous condensations, on the other hand, could possibly be understood in terms of a massive outflow from the central regions of the galaxy., Comment: Accepted for publication in The Astrophysical Journal

We studied mid-infrared (mid-IR) variability of AGN systematically combining two all-sky survey catalogs released by AKARI and Wide-field Infrared Survey Explorer (WISE). Because the two surveys are separated by approximately 4 years, our studies are sensitive to variations of time scales of a few years. We started with the list of AGN selected by Matsuta et al. (2012) from the cross-identification of Swift/BAT and AKARI catalogs. The list was further correlated with the WISE catalog to select a total of 71 AGN, which were used for the present studies. We compared source fluxes in the AKARI S9W (9μm) and WISE W3 (12μm) bands and in the AKARI L18W (18μm) and WISE W4 (22μm) bands carefully correcting for the band differences and considering the systematic effects. We detected significant flux changes from 3 sources, two blazars (3C 273, 3C 345) and a radio galaxy (3C 445), in the mid-IR bands. This is the first detection of mid-IR variability from 3C 445, which may be originated from the jets. We also analyzed average sample variability for different AGN types excluding these 3 variable sources. We detected significant variations from Seyfert 1 in the S9W-W3 band with 95% confidence limit; the average fractional variability reached 13% (6-18%). Two origins are conceivable for the variability: the dusty torus and the jets. If such variability originates from the torus, the dust distribution in the torus should be very narrow, and its radial extent may be much smaller than the distance to the AGN. Alternatively, the variability may result from the jets considered to be present in Seyfert 1 galaxies., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA1630016000, レポート番号: JAXA-RR-16-010E

The Neil Gehrels Swift Observatory carried out prompt searches for gravitational wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run ("O2"). Swift performed extensive tiling of eight LVC triggers, two of which had very low false-alarm rates (GW 170814 and the epochal GW 170817), indicating a high confidence of being astrophysical in origin; the latter was the first GW event to have an electromagnetic counterpart detected. In this paper we describe the follow-up performed during O2 and the results of our searches. No GW electromagnetic counterparts were detected; this result is expected, as GW 170817 remained the only astrophysical event containing at least one neutron star after LVC's later retraction of some events. A number of X-ray sources were detected, with the majority of identified sources being active galactic nuclei. We discuss the detection rate of transient X-ray sources and their implications in the O2 tiling searches. Finally, we describe the lessons learned during O2, and how these are being used to improve the \swift\ follow-up of GW events. In particular, we simulate a population of GRB afterglows to evaluate our source ranking system's ability to differentiate them from unrelated and uncatalogued X-ray sources. We find that $\approx$60-70% of afterglows whose jets are oriented towards Earth will be given high rank (i.e., "interesting" designation) by the completion of our second follow-up phase (assuming their location in the sky was observed), but that this fraction can be increased to nearly 100% by performing a third follow-up observation of sources exhibiting fading behavior., Comment: 18 pages, 4 figures, 2 tables, accepted for publication in ApJS

An inverse Compton scattering source is under development at the ELSA linac of CEA, Bruyeres-le-Châtel. Ultra-short X-ray pulses are produced by inverse Compton scattering of 30 ps-laser pulses by relativistic electron bunches. The source will be able to operate in single shot mode as well as in recurrent mode with 72.2 MHz pulse trains. Within this framework, an optical multipass system that multiplies the number of emitted X-ray photons in both regimes has been designed in 2014, then implemented and tested on ELSA facility in the course of 2015. The device is described from both geometrical and timing viewpoints. It is based on the idea of folding the laser optical path to pile-up laser pulses at the interaction point, thus increasing the interaction probability. The X-ray output gain measurements obtained using this system are presented and compared with calculated expectations.

The Crab Nebula is used by many instruments as a calibration source, in particular at high energy, where it is one of the brightest celestial object. The spectrometer INTEGRAL SPI (20 keV - 8 MeV), in operation since October 2002, offers a large dataset dedicated to this source, with regular campaigns planned twice per year. We have analyzed the available data to quantify the source behavior on a long term scale and examine the stability level on timescales from hour to years. As a result, the source flux variability appears to be contained within less than +/- 5% around a ~ 20 yr mean value, for broad bands covering the 20 keV - 400 keV energy domain, above which statistic limits any firm conclusion. In term of spectral shape, the Band model provides a good description of the observed emission between 20 keV and 2.2 MeV. The averaged spectrum best fit parameters correspond to a low energy slope of 1.99 +/- 0.01, a high energy slope of -2.32 +/- 0.02 and a characteristic energy E c of 531 +/- 50 keV to describe the curvature joining both power laws. The spectral parameters have then been determined on the revolution timescale (~ 1 to 2 days) and their steadiness confirms the source emission stability. As a complementary result, this study demonstrates that the SPI instrument efficiency remains within 5% of its initial value, after 17 years of operation., Comment: 8 figures. Accepted for publication in ApJ

The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in soft to hard X-ray channels. Its cartoon representation is found throughout textbooks on solar and plasma astrophysics, and guides interpretations of unresolved energetic flaring events on other stars, accretion disks and jets. To date, a fully self-consistent model that reproduces the standard scenario in all its facets is lacking, since this requires the combination of a large scale, multi-dimensional magnetohydrodynamic (MHD) plasma description with a realistic fast electron treatment. Here, we demonstrate such a novel combination, where MHD combines with an analytic fast electron model, adjusted to handle time-evolving, reconnecting magnetic fields and particle trapping. This allows to study (1) the role of fast electron deposition in the triggering of chromospheric evaporation flows; (2) the physical mechanisms that generate various hard X-ray sources at chromospheric footpoints or looptops; and (3) the relationship between soft X-ray and hard X-ray fluxes throughout the entire flare loop evolution. For the first time, this self-consistent solar flare model demonstrates the observationally suggested relationship between flux swept out by the hard X-ray footpoint regions, and the actual reconnection rate at the X-point, which is a major unknown in flaring scenarios. We also demonstrate that a looptop hard X-ray source can result from fast electron trapping., 23 pages, 11 figures

The recent discovery of the electromagnetic counterpart of the gravitational wave source GW170817, has demonstrated the huge informative power of multi-messenger observations. During the next decade the nascent field of multi-messenger astronomy will mature significantly. Around 2030, third generation gravitational wave detectors will be roughly ten times more sensitive than the current ones. At the same time, neutrino detectors currently upgrading to multi km^3 telescopes, will include a 10 km^3 facility in the Southern hemisphere that is expected to be operational around 2030. In this review, we describe the most promising high frequency gravitational wave and neutrino sources that will be detected in the next two decades. In this context, we show the important role of the Transient High Energy Sky and Early Universe Surveyor (THESEUS), a mission concept proposed to ESA by a large international collaboration in response to the call for the Cosmic Vision Programme M5 missions. THESEUS aims at providing a substantial advancement in early Universe science as well as playing a fundamental role in multi-messenger and time-domain astrophysics, operating in strong synergy with future gravitational wave and neutrino detectors as well as major ground- and space-based telescopes. This review is an extension of the THESEUS white paper (Amati et al. 2017), also in light of the discovery of GW170817/GRB170817A that was announced on October 16th, 2017., Comment: 25 pages, 13 figures, accepted to Advances in Space Research with minor revisions. Details on the THESEUS instrumentation, science case and expected performances can also be found in Amati et al. 2017 (arXiv:1710.04638) and in the presentations of the THESEUS Workshop 2017 (http://www.isdc.unige.ch/theseus/workshop2017-programme.html). v2 few typos corrected

We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65d variability period. We use the measured pulse periods to determine the orbital ephemeris, confirm a long orbital period with P_orb = 63.9 (+0.5,-0.6) d, and find an eccentricity of e, 10 pages, 6 figures, accepted for publication in A&A

By exploiting two ACS/HST datasets separated by a temporal baseline of ~7 years, we have determined the relative stellar proper motions (providing membership) and the absolute proper motion of the Galactic globular cluster M71. The absolute proper motion has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations to re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources., Accepted for publication in ApJ

The possibility of constructing terawatt (TW) x-ray free-electron lasers (FELs) has been discussed using novel superconducting helical undulators [5]. In this paper, we consider the conditions necessary for achieving powers in excess of 1 TW in a 1.5 {\AA} FEL using simulations with the MINERVA simulation code [7]. Steady-state simulations have been conducted using a variety of undulator and focusing configurations. In particular, strong focusing using FODO lattices is compared with the natural, weak focusing inherent in helical undulators. It is found that the most important requirement to reach TW powers is extreme transverse compression of the electron beam in a strong FODO lattice. The importance of extreme focusing of the electron beam in the production of TW power levels means that the undulator is not the prime driver for a TW FEL, and simulations are also described using planar undulators that reach near-TW power levels. In addition, TW power levels can be reached using pure self-amplified spontaneous emission (SASE) or with novel self-seeding configurations when such extreme focusing of the electron beam is applied., Comment: 10 pages, 12 figures

We apply the standard radio pulsar rotating vector model to the white dwarf pulsar AR Sco's optical polarization position angle swings folded at the white dwarf's spin period as obtained by Buckley et al. (2017). Owing to the long duty cycle of spin pulsations with a good signal-to-noise ratio over the entire spin phase, in contrast to neutron star radio pulsars, we find well-constrained values for the magnetic obliquity $\alpha$ and observer viewing direction $\zeta$ with respect to the spin axis. We find $\cos\alpha=0.060^{+0.050}_{-0.053}$ and $\cos\zeta=0.49^{+0.09}_{-0.08}$, implying an orthogonal rotator with an observer angle $\zeta={60.4^\circ}^{+5.3^\circ}_{-6.0^\circ}$. This orthogonal nature of the rotator is consistent with the optical light curve consisting of two pulses per spin period, separated by $180^\circ$ in phase. Under the assumption that $\zeta \approx i$, where $i$ is the orbital inclination, and a Roche-lobe-filling companion M star, we obtain $m_{\rm WD} = 1.00^{+0.16}_{-0.10} M_\odot$ for the white dwarf mass. These polarization modeling results suggest the that non-thermal emission arises from a dipolar white dwarf magnetosphere and close to the star, with synchrotron radiation (if non-zero pitch angles can be maintained) being the plausible loss mechanism, marking AR Sco as an exceptional system for future theoretical and observational study., Comment: 11 pages, 7 figures, accepted by ApJ

© 2016, Pleiades Publishing, Inc.Based on data from the SWIFT, INTEGRAL, MAXI/ISS orbital observatories, and the ground-based RTT-150 telescope, we have investigated the broadband (from the optical to the hard X-ray bands) spectrum of the X-ray nova MAXI J1828-249 and its evolution during the outburst of the source in 2013–2014. The optical and infrared emissions from the nova are shown to be largely determined by the extension of the power-law component responsible for the hard X-ray emission. The contribution from the outer cold regions of the accretion disk, even if the X-ray heating of its surface is taken into account, turns out to be moderate during the source’s “high” state (when a soft blackbody emission component is observed in the X-ray spectrum) and is virtually absent during its “low” (“hard”) state. This result suggests that much of the optical and infrared emissions from such systems originates in the same region of main energy release where their hard X-ray emission is formed. This can be the Compton or synchro-Compton radiation from a high-temperature plasma in the central accretion disk region puffed up by instabilities, the synchrotron radiation from a hot corona above the disk, or the synchrotron radiation from its relativistic jets.

We present the catalog of optical and infrared counterparts of the Chandra COSMOS-Legacy Survey, a 4.6 Ms Chandra program on the 2.2 square degrees of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6 micron identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 micron information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while 54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is available online. We study several X-ray to optical (X/O) properties: with our large statistics we put better constraints on the X/O flux ratio locus, finding a shift towards faint optical magnitudes in both soft and hard X-ray band. We confirm the existence of a correlation between X/O and the the 2-10 keV luminosity for Type 2 sources. We extend to low luminosities the analysis of the correlation between the fraction of obscured AGN and the hard band luminosity, finding a different behavior between the optically and X-ray classified obscured fraction., Comment: 28 pages, 14 figures, accepted to ApJ

Optical, UV and X-ray observations of the well known symbiotic star AG Draconis during quiescence and the active phase 1994/1995 are presented. The intensity in the UV region is well correlated with the optical activity. The observed X / ray flux dropped down by a factor of about 100 during the outburst maximum.

We examined X-ray, ultraviolet, and optical archival data of 89 supersoft X-ray sources (SSS) in M31. We studied the timescales of X-ray variability and searched UV and optical counterparts. Almost a third of the SSS are known classical or recurrent novae, and at least half of the others exhibit the same temporal behavior as post-outburst novae. Non-stellar objects among SSS seem to be rare: less than 10% of the classified SSS turned out to be supernova remnants, and only one source has been identified with an active galactic nucleus in the background. Not more than 20% of the SSS that are not coincident with observed novae are persistent or recurrent X-ray sources. A few of these long-lasting sources show characteristics in common with other SSS identified as white dwarf (WD) close binaries in the Magellanic Clouds and in the Galaxy, including variability on timescales of minutes, possibly indicating the spin period of a WD. Such objects are likely to be low-mass X-ray binaries with a massive WD. A third of the non-nova SSS are in regions of recent star formation, often at the position of an O or B star, and we suggest that they may be high-mass X-ray binaries. If these sources host a massive hydrogen-burning WD, as it seems likely, they may become Type Ia supernovae (SNe Ia), constituting the star formation dependent component of the SNe Ia rate.

Using the Infrared Spectrograph on the Spitzer Space Telescope, we observed the Antennae galaxies obtaining spectral maps of the entire central region and high signal-to-noise 5-38 mu m spectra of the two galactic nuclei and six infrared-luminous regions. The total infrared luminosity of our six IR peaks plus the two nuclei is L-IR = 3.8 x 10(10) L-circle dot, with their derived star formation rates ranging between 0.2 and 2 M-circle dot yr(-1), with a total of 6.6 M-circle dot yr(-1). None of the typical mid-IR tracers of active galactic nucleus activity is detected in either nucleus of the system, excluding the presence of a dust-enshrouded accretion disk. The hardest and most luminous radiation originates from two compact clusters in the southern part of the overlap region, which also have the highest dust temperatures. Polycyclic aromatic hydrocarbon (PAH) emission and other tracers of softer radiation are spatially extended throughout and beyond the overlap region, but regions with a harder and more intense radiation field show a reduced PAH strength. The strong H-2 emission is rather confined around the nucleus of NGC 4039, where shocks appear to be the dominant excitation mechanism, and the southern part of the overlap region, where it traces the most recent starburst activity. The luminosity ratio between the warm molecular gas (traced by the H-2 lines) and the total far-IR emission is similar to 1.6 x 10(-4), similar to that found in many starbursts and ultraluminous infrared galaxies. The total mass of warm H-2 in the Antennae is 2.5 x 10(7) M-circle dot, with a fraction of warm to total H-2 gas mass of about 0.35%. The average warm H-2 temperature is 302 +/- 26 K and appears anticorrelated with the radiation field hardness, possibly due to an evolution of the photodissociation region (PDR) morphology. The previously reported tight correlation between the H-2 and PAH emission was not found but higher total PAH emission to continuum ratios were found in PDRs with warmer gas.

Neste trabalho foram realizados testes de estabilidade e de caracterização de uma câmara de ionização de ar-livre com cilindros concêntricos da marca Victoreen, modelo 481. Os testes foram feitos utilizando feixes diretos de mamografia como uma contribuição para a implantação desta câmara como sistema padrão primário para a grandeza kerma no ar. Os testes de caracterização realizados foram: curva de saturação, eficiência de coleção de íons, efeito de polaridade, linearidade da resposta com a taxa de kerma no ar e linearidade da resposta com a variação volumétrica. O teste de eficiência de coleção de íons possibilitou a determinação do fator de correção para recombinação iônica. A maioria dos testes realizados esteve em conformidade com os limites estabelecidos por normas internacionais. Foram obtidos os fatores de correção para atenuação de fótons no ar para as qualidades de mamografia com filtros de alumínio e molibdênio. Foram determinados também os fatores de correção para transmissão e espalhamento de fótons nas bordas do diafragma para as qualidades de mamografia com filtro de alumínio e para a qualidade padrão de mamografia com filtro de molibdênio. At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribuition for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter.

LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be re- proposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities., Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91442W

© 2015, Pleiades Publishing, Inc. We present the results of the the identification of six objects from the ASCA Galactic center and Galactic plane surveys: AX J173548-3207, AX J173628-3141, AX J1739.5-2910, AX J1740.4-2856, AX J1740.5-2937, and AX J1743.9-2846. Chandra, XMM-Newton, and XRT/Swift X-ray data have been used to improve the positions of the optical counterparts to these sources. Thereafter, we have carried out a series of spectroscopic observations of the established optical counterparts at the RTT-150 telescope. Analysis of X-ray and optical spectra as well as photometric measurements in a wide wavelength range based on optical and infrared catalogs has allowed the nature of the program sources to be determined. Two X-ray objects have been detected in the error circle of AX J173628-3141: one is a coronally active G star and the other may be a symbiotic star, a red giant with an accreting white dwarf. Three sources (AX J1739.5-2910, AX J1740.5-2937, AX J1743.9-2846) have turned out to be active G-K stars, presumably RS CVn objects, one (AX J1740.4-2856) is an M dwarf, and another one (AX J173548-3207) most likely a low-mass X-ray binary in its low state. The distances and corresponding luminosities of the sources in the soft X-ray band (0.5–10 keV) have been estimated; analysis of deep INTEGRAL Galactic center observations has not revealed a statistically significant flux at energies >20 keV from any of them.

This paper presents the optical properties of the objects selected in the CLASS blazar survey. Because an optical spectrum is now available for 70 per cent of the 325 sources present in the sample, a spectral classification, based on the appearance of the emission/absorption lines, is possible. A wide variety of optical spectral types is found. Besides 'classical' BL Lacs (42), BL Lac candidates (5) and high-power (P-5 GHz > 10(26) W Hz(-1)) flat spectrum radio quasars (67), a significant number of 'passive' elliptical galaxies (41) is also found. Moreover, 33 broad emission line objects with a low radio Power (P-5 (GHz)

© 2014 IOP Publishing Ltd. Narrow bandwidth, high energy photon sources can be generated by Thomson scattering of laser light from energetic electrons, and detailed control of the interaction is needed to produce high quality sources. We present analytic calculations of the energy-angular spectra and photon yield that parametrize the influences of the electron and laser beam parameters to allow source design. These calculations, combined with numerical simulations, are applied to evaluate sources using conventional scattering in vacuum and methods for improving the source via laser waveguides or plasma channels. We show that the photon flux can be greatly increased by using a plasma channel to guide the laser during the interaction. Conversely, we show that to produce a given number of photons, the required laser energy can be reduced by an order of magnitude through the use of a plasma channel. In addition, we show that a plasma can be used as a compact beam dump, in which the electron beam is decelerated in a short distance, thereby greatly reducing radiation shielding. Realistic experimental errors such as transverse jitter are quantitatively shown to be tolerable. Examples of designs relevant to nuclear resonance fluorescence and photofission are provided.

Recently, we demonstrated that projective X-ray microscopy is feasible with a twodimensional spatial resolution down to 100 nm by using laboratory nanofocus X-ray sources and a geometric magnification of up to 1000x. Based on these previous results, we developed a high-resolution X-ray laminography system which uses an optimized thin-film X-ray transmission target together with a modified electron probe micro analyzer. Unlike conventional axial computed tomography (CT), 3D laminography imaging involves a linear translation of both detector and object with respect to a stationary point source. In this contribution we present a detailed characterization of the setup concerning especially the laminographic imaging mode. The quality of the volume reconstruction is assessed by simulating an ideal setup with an analytical model including features down to 200 nm which are resolved in the setup given a high enough SNR in the projections. We further address the issue of a drop in the detector resolution under oblique X-ray illumination which is a common problem to such systems. The finite penetration depth of the X-rays into the detector pixels causes an anisotropic blurring of the detector point spread function (PSF) under oblique irradiation. We tested the influence of this blurring by calculating the illuminationdependent modulation transfer function (MTF) of the detector. Our measurements are supported by numerical simulations of the detector MTF. Both simulations and measurements show a drop in spatial resolution (20% of the MTF) from 12.5 lp/mm (irradiation perpendicular to the detector screen) down to 5.2 lp/mm (irradiation 30 degrees oblique to the screen). Furthermore, first examples of 3D imaging of test structures and material imaging are given.

We report the observation of efficient steering of a 855 MeV electron beam at MAMI (MAinzer MIkrotron) facilities by means of planar channeling and volume reflection in a bent silicon crystal. A $30.5\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ thick plate of (211) oriented Si was bent to cause quasimosaic deformation of the (111) crystallographic planes, which were used for coherent interaction with the electron beam. The experimental results are analogous to those recorded some years ago at energy higher than 100 GeV, which is the only comparable study to date. Monte Carlo simulations demonstrated that rechanneling plays a considerable role in a particle's dynamics and hinders the spoiling of channeled particles. These results allow a better understanding of the dynamics of electrons subject to coherent interactions in a bent silicon crystal in the sub-GeV energy range, which is relevant for realization of innovative x-ray sources based on channeling in periodically bent crystals.

LOFT (Large Observatory For x-ray Timing) is one of the four missions selected in 2011 for assessment study for the ESA M3 mission in the Cosmic Vision program, expected to be launched in 2024. The LOFT mission will carry two instruments with their prime sensitivity in the 2-30 keV range: a 10 m^2 class large area detector (LAD) with a, Proceedings of SPIE, Vol. 8443, Paper No. 8443-88

Intermediate mass black holes (IMBHs) with expected masses M_BH ~ 10^4 M_sun are thought to bridge the gap between stellar mass black holes (M_BH ~ 3 - 100 M_sun) and supermassive black holes found at the centre of galaxies (M_BH > 10^6 M_sun). Until today, no IMBH has been confirmed observationally. The most promising objects to host an IMBH as their central mass are globular clusters. Here, we present high sensitivity multi-epoch 1.6 GHz very long baseline interferometry observations of the globular cluster M15 that has been suggested to host an IMBH. Assuming the IMBH to be accreting matter from its surrounding we expect to detect it as a point source moving with the global motion of the cluster. However, we do not detect any such object within a radius of 6000 AU of the cluster centre in any of the five observations spread over more than one year. This rules out any variability of the putative IMBH on the time scale of one to two months. To get the most stringent upper limit for the flux density of the putative IMBH we concatenate the data of all five epochs. In this data we measure a 3{\sigma} upper flux limit of 10 {\mu}Jy for a central source. We employ the fundamental plane of black hole activity to estimate the mass of the central IMBH candidate. Based on previous X-ray observations of M15 our measurements indicate a 3{\sigma} upper mass limit of ~500 M_sun., Comment: 6 pages, 2 figures, accepted for publication in A&A

We present results of optical identifications of six hard X-ray sources from the INTEGRAL and Swift all-sky surveys (IGR J03249+4041, SWIFT J1449. 5+8602, SWIFT J1542. 0-1410, IGR J17009+3559, IGR J18151-1052, IGR J18538-0102). Our optical observations were performed in 2009-2011 with the 6-m BTA telescope (Special Astrophysical Observatory, Nizhnii Arkhyz, Russia) and the 1. 5-m RTT-150 telescope (Turkish National Observatory, Antalya, Turkey). The optical spectra obtained for each of the program sources have allowed us to establish the nature of the objects and to measure their redshifts from the positions of emission and absorption lines. Five sources are shown to be extragalactic-four of them are identified with Seyfert 1 or 2 galaxies and the fifth source belongs to the class of X-ray-bright, optically normal galaxies (XBONGs). The sixth object (IGR J18151-1052) is located in our Galaxy and is an X-ray binary (XRB), a suspected cataclysmic variable. Apart from the optical spectra, we provide the X-ray spectra for five sources in the 0. 6-10 keV energy band obtained from XRT/Swift data. © 2012 Pleiades Publishing, Ltd.

We discuss a new compact gamma-ray source aiming at high spectral density, up to two orders of magnitude higher than currently available bremsstrahlung sources, and conceptually similar to Compton Sources based on conventional linear accelerators. This new source exploits electron bunches from laser-driven electron acceleration in the so-called self-injection scheme and uses a counter-propagating laser pulse to obtain X and gamma-ray emission via Thomson/Compton scattering. The proposed experimental configuration inherently provides a unique test-bed for studies of fundamental open issues of electrodynamics. In view of this, a preliminary discussion of recent results on self-injection with the FLAME laser is also given., Comment: 8 pages, 10 figures, 44 references - Channeling 2012 conference

The Scientific objectives of the LOFT mission, e.g., the study of the Neutron Star equation of state and of the Strong Gravity, require accurate energy, time and flux calibration for the 500k channels of the SDD detectors, as well as the knowledge of the detector dead-time and of the detector response with respect to the incident angle of the photons. We report here the evaluations made to asses the calibration issues for the LAD instrument. The strategies for both ground and on-board calibrations, including astrophysical observations, show that the goals are achievable within the current technologies., Comment: Proceedings of SPIE, Vol. 8443, Paper No. 8443-208, 2012

Nowadays, the analysis of the X-ray spectra of magnetically powered neutron stars or magnetars is one of the most valuable tools to gain insight into the physical processes occurring in their interiors and magnetospheres. In particular, the magnetospheric plasma leaves a strong imprint on the observed X-ray spectrum by means of Compton up-scattering of the thermal radiation coming from the star surface. Motivated by the increased quality of the observational data, much theoretical work has been devoted to develop Monte Carlo (MC) codes that incorporate the effects of resonant Compton scattering in the modeling of radiative transfer of photons through the magnetosphere. The two key ingredients in this simulations are the kinetic plasma properties and the magnetic field (MF) configuration. The MF geometry is expected to be complex, but up to now only mathematically simple solutions (self-similar solutions) have been employed. In this work, we discuss the effects of new, more realistic, MF geometries on synthetic spectra. We use new force-free solutions in a previously developed MC code to assess the influence of MF geometry on the emerging spectra. Our main result is that the shape of the final spectrum is mostly sensitive to uncertain parameters of the magnetospheric plasma, but the MF geometry plays an important role on the angle-dependence of the spectra., Comment: 6 pages, 4 figures To appear in Proceedings of II Iberian Nuclear Astrophysics Meeting held in Salamanca, September 22-23, 2011

In this paper we report on the development and characterisation of an industrial computed tomography (ICT) system to image larger aerospace components and assemblies with sizes up to φ1000 mm, 10 m height and 2000 kg weight. The system consists of a 450 kV X-ray source, a linear detector array and a 6-axes computer numerical control (CNC) object manipulator. Mechanical as well as radiographic alignments were carried out to achieve 10 μm accuracy in mechanical motion of the objects under study. Rotate-only and translate-rotate scanning geometries were implemented for different sizes of object. Bi-directional scanning was implemented in translate-rotate geometry to reduce the scanning time by half. Corrections for centre of rotation error, ring artifacts, streak artifacts, unequal ray spacing error and cupping (beam-hardening) artifacts are implemented. A filtered back projection (FBP) algorithm is implemented for image reconstruction. The modulation transfer function (MTF) of the system is estimated using a 160 mm-diameter Perspex cylinder. The system resolution is found to be 350 μm. Details on the scanning of a few components are presented. 3D isovalue surface generation is implemented as an additional feature to aid better defect evaluation.

We report the temporal and spectral results on the INTEGRAL and RXTE 2006-2007 observation campaign of the Atoll source 4U 1728-34 (GX 354-0). The source shows, more than once, spectral evolution as revealed by the hardness intensity diagram. The soft state is well described by a Comptonization with an electron temperature of 3 keV and a high optical depth of 6. In the hard spectral state the emission extends to above 100 keV and it can be described by Comptoniziation (with higher temperature of 10 keV) plus a power law component with Γ of 1.8, which is evidence for non-thermal emission from the source.

Princip predostrožnosti jedan je od osnovnih principa na kojima počiva politika zaštite okoliša i ljudskog zdravlja Europske Unije. Pojačanu brigu za ljudsko zdravlje izazvao je i progresivni razvoj tehnologija za bežični prijenos telekomunikacijskog signala bez obzira na njihovu očiglednu sociološku i ekonomsku korist društvu. Svjedoci smo i naglog razvoja novih digitalnih tehnologija koje se koriste elektromagnetskim rendgenskim zračenjem u medicinskoj dijagnostici. Iako prirodno elektromagnetsko zračenje iz svemira ne doseže u potpunosti, osim u nekoliko intervala frekvencija, do Zemljine površine, neionizirajuće prirodno zračenje pokriva Zemlju značajno kompliciranije nego što to čini ionizirajuće elektromagnetsko zračenje. U radu su razmatrane vrlo niske i niske doze elektromagnetskoga rendgenskog zračenja koje primaju bolesnici za vrijeme medicinske dijagnostike. Trenutačno nema dovoljno znanstvenih podataka za prihvatljivu evaluaciju rizika od izlaganja ljudi visokofrekventnom elektromagnetskom neionizirajućem zračenju niskih i vrlo niskih doza. Zajedno s naglim razvojem i uporabom elektromagnetskoga rendgenskog zračenja razvijaju se i proizvode izvori neionizirajućeg zračenja utječući na okoliš i biotu na način koji nikako nije zanemariv. Zbog toga se predlaže holistički, specifi čniji dubinsko ekološki pristup zaštiti stanovništva Republike Hrvatske od izlaganja ionizirajućem i neionizirajućem umjetnom zračenju., The precautionary principle is explicitly laid down in the EU Treaty and is one of the starting points of the EU environmental policy. The concern over human health has been raised by extended use of mobile and wireless telecommunication technologies, regardless of their obvious economic and societal benefits for the modern society. We are also experiencing a growth in new electromagnetic X-ray technologies for medical diagnostics. Natural electromagnetic radiation from space does not reach the Earth’s surface, except at a very few wavelengths, but non-ionising background radiation covers the globe in a much more complex space matrix than background electromagnetic ionising radiation. This article looks into patient exposure to low-dose, high-frequency, non-ionising electromagnetic X-ray radiation from digital diagnostics machines. At present, there are not enough data to assess public health risk. As man-made ionising and non-ionising radiation sources are expanding enormously, we need to take a holistic as well as a more specifi c, deep ecology approach to protect Croatian population.

Using the Infrared Spectrograph on the Spitzer Space Telescope, we observed the Antennae galaxies obtaining spectral maps of the entire central region and high signal-to-noise 5-38 um spectra of the two galactic nuclei and six infrared-luminous regions. The total infrared luminosity of our six IR peaks plus the two nuclei is L_IR = 3.8x10^10 L_o, with their derived star formation rates ranging between 0.2 and 2 M_o/yr, with a total of 6.6 M_o/yr. The hardest and most luminous radiation originates from two compact clusters in the southern part of the overlap region, which also have the highest dust temperatures. PAH emission and other tracers of softer radiation are spatially extended throughout and beyond the overlap region, but regions with harder and intenser radiation field show a reduced PAH strength. The strong H_2 emission is rather confined around the nucleus of NGC 4039, where shocks appear to be the dominant excitation mechanism, and the southern part of the overlap region, where it traces the most recent starburst activity. The luminosity ratio between the warm molecular gas (traced by the H_2 lines) and the total far-IR emission is ~1.6x10^-4, similar to that found in many starburst and ULIRGs. The total mass of warm H_2 in the Antennae is 2.5x10^7 M_o, with a fraction of warm to total H_2 gas mass of about 0.35%. The average warm H_2 temperature is 302+/-26 K and appears anti-correlated with the radiation field hardness, possibly due to an evolution of the PDR morphology. The previously reported tight correlation between the H_2 and PAH emission was not found but higher total PAH emission to continuum ratios were found in PDRs with warmer gas., Comment: 24 pages, 13 figures, accepted by ApJ, full resolution version at http://www.strw.leidenuniv.nl/~brandl/ngc4038_brandl.pdf