The emerging population of pulsar wind nebulae in hard X-rays

The hard X-ray synchrotron emission from pulsar wind nebulae (PWNe) probes energetic particles, closely related to the pulsar injection power at the present time. INTEGRAL has disclosed the yet poorly known population of hard X-ray pulsar/PWN systems. We summarize the properties of the class, with emphasys on the first hard X-ray bow-shock (CTB 80 powered by PSR B1951+32), and highlight some prospects for the study of Pulsar Wind Nebulae with the Simbol-X mission.Comment: Proceedings of the 2nd Simbol-X Symposium, AIP Conf. Proc. Series, Eds. P. Ferrando and J. Rodriguez (4 pages, 2 figures

The first Suzaku observation of SGR 1806-20

The soft gamma-ray repeater SGR 1806-20 has been attracting a lot of attention owing to the fact that in December 2004 it emitted the most powerful giant flare ever observed. Here we present the results of the first Suzaku observation of SGR 1806-20, that seems to have reached a state characterized by a flux close to the pre-flare level and by a relatively soft spectrum. Despite this, the source remained quite active, as testified by several short bursts observed by Suzaku. We discuss the broadband spectral properties of SGR 1806-20 in the context of the magnetar model, considering its recent theoretical developments.Comment: 3 pages, 1 figure. Proceedings of the conference "40 Years of Pulsars, Millisecond Pulsars, Magnetars and More", Montreal, August 12-17 2007. AIP, in pres

SVOM: a new mission for Gamma-Ray Burst Studies

We present the SVOM (Space-based multi-band astronomical Variable Object Monitor) mission, that is being developed in cooperation between the Chinese National Space Agency (CNSA), the Chinese Academy of Science (CAS) and the French Space Agency (CNES). Its scientific objectives include the study of the GRB phenomenon, GRB physics and progenitors, cosmology, and fundamental physics. SVOM is designed to detect all known types of Gamma-Ray Bursts (GRBs), to provide fast and reliable GRB positions, to measure the broadband spectral characteristics and temporal properties of the GRB prompt emission. This will be obtained in first place thanks to a set of four space flown instruments. A wide field (~2 sr) coded mask telescope (ECLAIRs), operating in the 4-250 keV energy range, will provide the triggers and localizations, while a gamma-ray non-imaging spectrometer (GRM), sensitive in the 50 keV-5 MeV domain, will extend the prompt emission energy coverage. After a satellite slew, in order to place the GRB direction within field of view of the two narrow field instruments - a soft X-ray (XIAO), and a visible telescope (VT) - the GRB position will be refined and the study of the early phases of the GRB afterglow will be possible. A set of three ground based dedicated instruments, two robotic telescopes (GFTs) and a wide angle optical monitor (GWAC), will complement the space borne instruments. Thanks to the low energy trigger threshold (~4 keV) of the ECLAIRs, SVOM is ideally suited for the detection of soft, hence potentially most distant, GRBs. Its observing strategy is optimized to facilitate follow-up observations from the largest ground based facilities.Comment: Proceedings of the 6th Huntsville Symposium on Gamma-Ray Bursts (October 20-23 2008). Figures in colour with respect to the published versio

Electronically Stabilized Nonplanar Phenalenyl Radical and Its Planar Isomer

Stable phenalenyl radicals have great potential as the basis for new materials for applications in the field of molecular electronics. In particular, electronically stabilized phenalenyl species that do not require steric shielding are molecules of fundamental interest, but are notoriously difficult to synthesize. Herein, the synthesis and characterization of two phenalenyl-type cations is reported: planar benzo­[<i>i</i>]­naphtho­[2,1,8-<i>mna</i>]­xanthenium (<b>8</b>⁺) and helical benzo­[<i>a</i>]­naphtho­[8,1,2-<i>jkl</i>]­xanthenium (<b>9</b>⁺), which can be reduced to the corresponding radicals. Radical <b>9</b> represents the first stable, helical phenalenyl radical which does not rely on bulky substituents to ensure its stability. Both cations are water-soluble, and the radicals are stable for weeks at room temperature under air. These compounds were characterized crystallographically, and also by NMR, EPR, electrochemistry, and electronic spectra. The synthesis of the previously reported compound benzo­[5,6]­naphthaceno­[1,12,11,10-<i>jklmna</i>]­xanthylium (<b>5</b>⁺), the largest oxygen-containing polycyclic hydrocarbon, was undertaken for comparison with <b>8</b>⁺ and <b>9</b>⁺, allowing us to report its crystal structure here for the first time. The different properties of these compounds and their radicals are explained by considering their differing aromaticities using in-depth computational methods

Discovery of 2.6 s pulsations in SGR1627–41

Here we report on XMM-Newton and Chandra observations that allowed us to measure the pulsation period and spin-down rate of SGR 1627-41, the only known magnetar for which these key pieces of information were still missing

Naphthoxanthenyl, a New Stable Phenalenyl Type Radical Stabilized by Electronic Effects

Naphthoxanthenyl <b>1</b> is a new stable phenalenyl-type radical. Electrochemical studies indicate that <b>1</b> has two reversible redox processes that occur on comparatively short time scales. Crystals containing <b>1</b> can be grown by electrocrystallization, suggesting that they are conductive