Hiroshi Tsunemi

In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS

We report the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation started on August 8, 2009, confirmed the basic performances of the effective area in the energy band of 2--30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1.5 degree FWHM, the source visibility of 40-150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at the similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to the high latitude. We also present the status of the in-orbit operation and the calibration of the effective area and the energy response matrix using Crab-nebula data.

SUZAKU OBSERVATIONS OF THE DIFFUSE X-RAY EMISSION ACROSS THE FERMI BUBBLES' EDGES

We present SuzakuX-ray observations along two edge regions of the Fermi Bubbl es, with eight≃ 20 ksec pointings across the northern part of the North Polar Spur (N PS) surrounding the north bubble and six across the southernmost edge of the south bubble. After removing co mpact X-ray features, diffuse X-ray emission is clearly detected and is well reproduced by a three-componen t sp ctral model consisting of unabsorbed thermal emission (temperature kT ≃ 0.1 keV) from the Local Bubble (LB), absorbed kT ≃ 0.3 keV thermal emission related to the NPS and/or Galactic Halo (GH), and a power-law component at a level consistent with the cosmic X-ray background. The emission measure (EM) of the 0. 3 keV plasma decreases by ≃ 50% toward the inner regions of the north-east bubble, with no accompan ying temperature change. However, such a jump in the EM is not clearly seen in the south bubble data. While it is unclear if the NPS originates from a nearby supernova remnant or is related to previous activity wi hin/around the Galactic Center, our Suzaku observations provide evidence suggestive of the latter sce nario. In the latter framework, the presence of a large amount of neutral matter absorbing the X-ray emission as wel l as the existence of the kT ≃ 0.3 keV gas can be naturally interpreted as a weak shock driven by the bubble s’ expansion in the surrounding medium, with velocityvexp ∼ 300 km s (corresponding to shock Mach number M ≃ 1.5), compressing the GH gas to form the NPS feature. We also derived an upper limit for any non-th ermal X-ray emission component associated with the bubbles and demonstrate, that in agreement with the findings above, the non-thermal pressure and energy estimated from a one-zone leptonic model of its broad -band spectrum, are in rough equilibrium with that of the surrounding thermal plasma. Subject headings: acceleration of particles — cosmic rays — Galaxy: center — Ga laxy: halo — X-rays: ISM

Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006-2007 outburst

Context. The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the radio and optical bands in the past, with the main outbursts repeating every 5–6 years. However, the predicted 2004 outburst did not occur, and further analysis suggested a longer time scale, according to which the next event would have occurred in the 2006–2007 observing season. Moreover, an extra emission component contributing to the UV and soft X-ray flux was detected, whose nature is not yet clear. An optical outburst was observed in late 2006–early 2007, which triggered a Whole Earth Blazar Telescope (WEBT) campaign as well as target of opportunity (ToO) observations by the Swift satellite. Aims. In this paper, we present the radio-to-optical data taken by the WEBT together with the UV data acquired by the UltraViolet and Optical Telescope (UVOT) instrument onboard Swift to investigate both the outburst behaviour at different wavelengths and the nature of the extra emission component. Methods. Multifrequency light curves have been assembled with data from 27 observatories; optical and UV fluxes have been cleaned from the contamination of the southern active galactic nucleus (AGN). We have analysed spectral energy distributions at different epochs, corresponding to different brightness states; extra absorption by the foreground galaxy has been taken into account. Results. We found the optical outburst to be as strong as the big outbursts of the past: starting from late September 2006, a brightness increase of ~5 mag led to the outburst peak in February 19–21, 2007. We also observed an outburst at mm and then at cm wavelengths, with an increasing time delay going toward lower frequencies during the rising phase. Cross-correlation analysis indicates that the 1 mm and 37 GHz flux variations lagged behind the R -band ones by about 3 weeks and 2 months, respectively. These short time delays suggest that the corresponding jet emitting regions are only slightly separated and/or misaligned. In contrast, during the outburst decreasing phase the flux faded contemporaneously at all cm wavelengths. This abrupt change in the emission behaviour may suggest the presence of some “shutdown” mechanism of intrinsic or geometric nature. The behaviour of the UV flux closely follows the optical and near-IR one. By separating the synchrotron and extra component contributions to the UV flux, we found that they correlate, which suggests that the two emissions have a common origin.

Solid-State Slit Camera (SSC) Aboard MAXI

Solid-state Slit Camera (SSC) is an X-ray camera onboard the MAXI mission of the International Space Station. Two sets of SSC sensors view X-ray sky using charge-coupled devices (CCDs) in 0.5--12\,keV band. The total area for the X-ray detection is about 200\,cm

THE SLOW X-RAY EXPANSION OF THE NORTHWESTERN RIM OF THE SUPERNOVA REMNANT RX J0852.0-4622

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POSSIBLE CHARGE-EXCHANGE X-RAY EMISSION IN THE CYGNUS LOOP DETECTED WITH SUZAKU

which is the largest among the missions of X-ray astronomy. The energy resolution at the CCD temperature of

The Plasma Structure of the Cygnus Loop from the Northeastern Rim to the Southwestern Rim

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Suzaku Observations of Tycho's Supernova Remnant

70 \degc is 145\,eV in full width at the half maximum (FWHM) at 5.9\,keV, and the field of view is 1\deg .5 (FWHM)

Discovery of Fast-Moving X-Ray--Emitting Ejecta Knots in the Oxygen-Rich Supernova Remnant Puppis A

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The NeXT Mission

90\deg for each sensor. The SSC could make a whole-sky image with the energy resolution good enough to resolve line emissions, and monitor the whole-sky at the energy band of