High Temporal Resolution XMM Monitoring of PKS 2155-304

The bright, strongly variable BL Lac object PKS 2155-304 was observed by XMM for two essentially uninterrupted periods of ~11 and 16 hr on 30-31 May 2000. The strongest variations occurred in the highest energy bands. After scaling for this effect, the three softest bands (0.1-1.7 keV) showed strong correlation with no measurable lag to reliable limits of \tau \ls 0.3 hr. However, the hardest band (~3 keV) was less well-correlated with the other three, especially on short time scales, showing deviations of ~10-20% in ~1 hr although, again, no significant interband lag was detected. This result and examination of previous ASCA and BeppoSAX cross-correlation functions suggest that previous claims of soft lags on time scales of 0.3-4 hr could well be an artifact of periodic interruptions due to Earth-occultation every 1.6 hr. Previous determinations of the magnetic field/bulk Lorentz factor were therefore premature, as these data provide only a lower limit of B \gamma^{1/3} \gs 2.5 G. The hardest band encompasses the spectral region above the high-energy break; its enhanced variability could be indicating that the break energy of the synchrotron spectrum, and therefore of the underlying electron energy distribution, changes independently of the lower energies.Comment: 13 pages, 3 figures, accepted by Ap

Timing analysis of the isolated neutron star RX J0720.4-3125

We present a combined analysis of XMM-Newton, Chandra and Rosat observations of the isolated neutron star RXJ0720.4-3125, spanning a total period of \sim 7 years. We develop a maximum likelihood periodogramme for our analysis based on the \Delta C-statistic and the maximum likelihood method, which are appropriate for the treatment of sparse event lists. Our results have been checked "a posteriori" by folding a further BeppoSAX dataset with the period predicted at the time of that observation: the phase is found to be consistent. The study of the spin history and the measure of the spin-down rate is of extreme importance in discriminating between the possible mechanisms suggested for the nature of the X-ray emission. The value of \dot P, here measured for the first time, is \approx 10^{-14} s/s. This value can not be explained in terms of torque from a fossil disk. When interpreted in terms of dipolar losses, it gives a magnetic field of B \approx 10^{13} G, making also implausible that the source is accreting from the underdense surroundings. On the other hand, we also find unlikely that the field decayed from a much larger value (B\approx 10^{15} G, as expected for a magnetar powered by dissipation of a superstrong field) since this scenario predicts a source age of \approx 10^4 yrs, too young to match the observed X-ray luminosity. The observed properties are more compatible with a scenario in which the source is \approx 10^6 yrs old, and its magnetic field has not changed substantially over the lifetime.Comment: 11 Pages, 6 Figures. Accepted for publication in MNRA

The SMC SNR 1E0102.2-7219 as a Calibration Standard for X-ray Astronomy in the 0.3-2.5 keV Bandpass

The flight calibration of the spectral response of CCD instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. We have been using 1E 0102.2-7219, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate the response models of the ACIS CCDs on the Chandra X-ray Observatory (CXO), the EPIC CCDs on the XMM-Newton Observatory, the XIS CCDs on the Suzaku Observatory, and the XRT CCD on the Swift Observatory. E0102 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of E0102 has been well characterized using high-resolution grating instruments, namely the XMM-Newton RGS and the CXO HETG, through which a consistent spectral model has been developed that can then be used to fit the lower-resolution CCD spectra. We have also used the measured intensities of the lines to investigate the consistency of the effective area models for the various instruments around the bright O (~570 eV and 654 eV) and Ne (~910 eV and 1022 eV) lines. We find that the measured fluxes of the O VII triplet, the O VIII Ly-alpha line, the Ne IX triplet, and the Ne X Ly-alpha line generally agree to within +/-10 % for all instruments, with 28 of our 32 fitted normalizations within +/-10% of the RGS-determined value. The maximum discrepancies, computed as the percentage difference between the lowest and highest normalization for any instrument pair, are 23% for the O VII triplet, 24% for the O VIII Ly-alpha line, 13% for the Ne IX triplet, and 19% for the Ne X Ly-alpha line. If only the CXO and XMM are compared, the maximum discrepancies are 22% for the O VII triplet, 16% for the O VIII Ly-alpha line, 4% for the Ne IX triplet, and 12% for the Ne X Ly-alpha line.Comment: 16 pages, 11 figures, to be published in Proceedings of the SPIE 7011: Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray 200

Mshpy23: a user-friendly, parameterized model of magnetosheath conditions

Lunar Environment heliospheric X-ray Imager (LEXI) and Solar wind−Magnetosphere−Ionosphere Link Explorer (SMILE) will observe magnetosheath and its boundary motion in soft X-rays for understanding magnetopause reconnection modes under various solar wind conditions after their respective launches in 2024 and 2025. Magnetosheath conditions, namely, plasma density, velocity, and temperature, are key parameters for predicting and analyzing soft X-ray images from the LEXI and SMILE missions. We developed a user-friendly model of magnetosheath that parameterizes number density, velocity, temperature, and magnetic field by utilizing the global Magnetohydrodynamics (MHD) model as well as the pre-existing gas-dynamic and analytic models. Using this parameterized magnetosheath model, scientists can easily reconstruct expected soft X-ray images and utilize them for analysis of observed images of LEXI and SMILE without simulating the complicated global magnetosphere models. First, we created an MHD-based magnetosheath model by running a total of 14 OpenGGCM global MHD simulations under 7 solar wind densities (1, 5, 10, 15, 20, 25, and 30 cm\begin{document}$^{-3}$\end{document}) and 2 interplanetary magnetic field \begin{document}$B_z$\end{document} components (± 4 nT), and then parameterizing the results in new magnetosheath conditions. We compared the magnetosheath model result with THEMIS statistical data and it showed good agreement with a weighted Pearson correlation coefficient greater than 0.77, especially for plasma density and plasma velocity. Second, we compiled a suite of magnetosheath models incorporating previous magnetosheath models (gas-dynamic, analytic), and did two case studies to test the performance. The MHD-based model was comparable to or better than the previous models while providing self-consistency among the magnetosheath parameters. Third, we constructed a tool to calculate a soft X-ray image from any given vantage point, which can support the planning and data analysis of the aforementioned LEXI and SMILE missions. A release of the code has been uploaded to a Github repository

Two methods for separating the magnetospheric solar wind charge exchange soft X-ray emission from the diffuse X-ray background

Solar wind charge exchange (SWCX) is the process of solar wind high-valence ions exchanging charges with neutral components and generating soft X-rays. Recently, detecting the SWCX emission from the magnetosphere is proposed as a new technique to study the magnetosphere using panoramic soft X-ray imaging. To better prepare for the data analysis of upcoming magnetospheric soft X-ray imaging missions, this paper compares the magnetospheric SWCX emission obtained by two methods in an XMM-Newton observation, during which the solar wind changed dramatically. The two methods differ in the data used to fit the diffuse X-ray background (DXB) parameters in spectral analysis. The method adding data from the ROSAT All-Sky Survey (RASS) is called the RASS method. The method using the quiet observation data is called the Quiet method, where quiet observations usually refer to observations made by the same satellite with the same target but under weaker solar wind conditions. Results show that the spectral compositions of magnetospheric SWCX emission obtained by the two methods are very similar, and the changes in intensity over time are highly consistent, although the intensity obtained by the RASS method is about \begin{document}$2.68\,\pm\, 0.56$\end{document} keV \begin{document}${\rm{cm}}^{-2} {\rm{s}}^{-1} {\rm{sr}}^{-1}$\end{document} higher than that obtained by the Quiet method. Since the DXB intensity obtained by the RASS method is about \begin{document}$2.84\,\pm\, 0.74$\end{document} keV \begin{document}${\rm{ cm}}^{-2} {\rm{s}}^{-1} {\rm{sr}}^{-1}$\end{document} lower than that obtained by the Quiet method, and the linear correlation coefficient between the difference of SWCX and DXB obtained by the two methods in different energy band is close to −1, the differences in magnetospheric SWCX can be fully attributed to the differences in the fitted DXB. The difference between the two methods is most significant when the energy is less than 0.7 keV, which is also the main energy band of SWCX emission. In addition, the difference between the two methods is not related to the SWCX intensity and, to some extent, to solar wind conditions, because SWCX intensity typically varies with the solar wind. In summary, both methods are robust and reliable, and should be considered based on the best available options

SMILE: a joint ESA/CAS mission to investigate the interaction between the solar wind and Earth's magnetosphere

The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a collaborative science mission between ESA and the Chinese Academy of Sciences (CAS). SMILE is a novel self-standing mission to observe the coupling of the solar wind and Earth's magnetosphere via X-Ray imaging of the solar wind -- magnetosphere interaction zones, UV imaging of global auroral distributions and simultaneous in-situ solar wind, magnetosheath plasma and magnetic field measurements. The SMILE mission proposal was submitted by a consortium of European, Chinese and Canadian scientists following a joint call for mission by ESA and CAS. It was formally selected by ESA's Science Programme Committee (SPC) as an element of the ESA Science Program in November 2015, with the goal of a launch at the end of 2021. In order to achieve its scientific objectives, the SMILE payload will comprise four instruments: the Soft X-ray Imager (SXI), which will spectrally map the Earth's magnetopause, magnetosheath and magnetospheric cusps; the UltraViolet Imager (UVI), dedicated to imaging the auroral regions; the Light Ion Analyser (LIA) and the MAGnetometer (MAG), which will establish the solar wind properties simultaneously with the imaging instruments. We report on the status of the mission and payload developments and the findings of a design study carried out in parallel at the concurrent design facilities (CDF) of ESA and CAS in October/November 2015

Invited Article: First Flight in Space of a Wide-Field-of-View Soft X-Ray Imager Using Lobster-Eye Optics: Instrument Description and Initial Flight Results

We describe the development, launch into space, and initial results from a prototype wide eld-of-view (FOV) soft X-ray imager that employs Lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The Sheath Transport Observer for the Redistribution of Mass (STORM) is the rst instrument using this type of optics launched into space and provides proof-of-concept for future ight instruments capable of imaging structures such as the terrestrial cusp, the entire dayside magnetosheath from outside the magnetosphere, comets, the moon, and the solar wind interaction with planetary bodies like Venus and Mars