Abstract During an X-ray observation of the distant galaxy cluster CL 0107+31 (z = 0.69) with ASCA, an extended X-ray source was detected in the field of view. Based on an image analysis in two different energy bands of 1–3 keV and 3–10 keV, we found that this source consists of a hard point-like component and an additional soft diffuse X-ray source extended over ≥ 3′ in radius. However, due to poor photon statistics, we could not distinguish whether their X-ray spectra are thermal or non-thermal. The peak position of the central X-ray source coincides with a radio-loud quasar, NRAO 58. NRAO 58 is found to have a power-law spectrum with a photon index $1.6^{+0.3}_{-0.2}$ and a (2–10 keV) luminosity of ∼ 4×46 erg s−1 (in the quasar rest frame). The extended component is likely to be a candidate for a nearby galaxy group which accidentally coincides with the quasar.
Abstract We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5−0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8–80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Γ1 = 1.74 ± 0.02 and Γ2 = 2.14 ± 0.01 below and above the break at 7.1 ± 0.3 keV, which is significantly lower than the NuSTAR result (∼9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833−1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 σ. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.
We have been developing the high throughput hard X-ray telescope, using reflectors coated with the depth graded multilayer known as supermirror, which is considered to be a key technology for future satellite hard X-ray imaging missions. InFOC(mu) $S, the International Focusing Optics Collaboration for (mu) -Crab Sensitivity is the project of the balloon observation of a cosmic hard X-ray source with this type of hard X-ray telescope and CdZnTe pixel detector as a focal plane imager. For the fist InFOC(mu) S balloon experiment, we developed the hard X-ray telescope with outermost diameter of 40cm, focal length of 8m and energy band pass of 20-40 keV, for which Pt/C multilayer was used. From the pre-flight X-ray calibration, we confirmed its energy band and imaging capability of 2 arcmin HPD and 10 arcmin FOV of FWHM, and a effective area of 50 cm2 for 20-40 keV X-ray. We report the current status of our balloon borne experiment and performance of our hard X-ray telescope.
Much attempts of statistical approach have been made to study the origin of heavy elements, distribution of dark matter and evolution of clusters of galaxies. Henry et al.(1991) reported a power-law relation; L X ∝ kT γ , γ ~ 2.7. Edge and Stwert(1991) found significant scatter in the correlation using 45 clusters. David at al.(1993) reported γ ~ 3.4 using 104 clusters.
