田代 信

The Soft X-ray Spectrometer (SXS) onboard the NeXT (New exploration X-ray Telescope) is an X-ray spectrometer utilizing an X-ray microcalorimeter array. Combined with the soft X-ray telescope of 6 m focal length, the instrument will have a ∼ 290cm2 effective at 6.7 keV. With the large effective area and the energy resolution as good as 6 eV (FWHM), the instrument is very suited for the high-resolution spectroscopy of iron K emission line. One of the major scientific objectives of SXS is to determine turbulent and/or macroscopic motions of the hot gas in clusters of galaxies of up to z ∼ 1. The instruments will use 6 × 6 or 8 × 8 format microcalorimeter array which is similar to that of Suzaku XRS. The detector will be cooled to a cryogenic temperature of 50 mK by multi-stage cooling system consisting of adiabatic demagnetization refrigerator, super fluid He, a 3He Joule Thomson cooler, and double-stage Stirling cycle cooler.

The NeXT (New exploration X-ray Telescope). the new Japanese X-ray Astronomy Satellite following Suzaku, is all international X-ray mission which is currently planed for launch in 2013. NeXT is a combination of wide band X-ray spectroscopy (3-80 keV) provided by multi-layer coating, focusing hard X-ray mirror and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-10 keV) provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane detector for a soft, X-ray telescope and a non-focusing soft, gamma-ray detector. With these instruments, NeXT Covers very wide energy range from 0.3 keV to 600 keV. The micro-calorimeter system will be developed by international collaboration lead ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of Delta E similar to 7 eV by the micro-calorimeter will enable a wide variety of important, science themes to be pursued.

The Wide-Field Telescope for Gamma-ray burst (GRB) Early Timing (WIDGET) is a robotic telescope aiming to observe the optical emission associated with the GRB. The system has a 64°×64° wide field-of-view and tracks the Swift/BAT field-of-view automatically. The WIDGET had been operated at Akeno campus of the Institute for Cosmic Ray Research of the University of Tokyo through May 2004 to October 2006, and has been moved to Kiso observatory, IoA, University of Tokyo. For two years in Akeno, the WIDGET succeeded to observe the GRB position seven times simultaneously with the HETE2 or Swift. Based on the successful operation in Akeno, we have moved and improved the system to Kiso observatory to realize more sensitive and efficient observation. These major improvements have been carried out until March 2007 and we have succeeded to reduce the background and achieved the limiting magnitude of Mv=11-12 after color correction. © 2008 American Institute of Physics.

The Hard X-ray Imager (HXI) is one of three focal plane detectors on board the NeXT (New exploration X-ray Telescope) mission, which is scheduled to be launched in 2013. By use of the hybrid structure composed of double-sided silicon strip detectors and a cadmium telluride strip detector, it fully covers the energy range of photons collected with the hard X-ray telescope up to 80 keV with a high quantum efficiency. High spatial resolutions of 400 micron pitch and energy resolutions of 1-2 keV (FWMH) are at the same time achieved with low noise front-end ASICs. In addition, thick BGO active shields compactly surrounding the main detection part, as a heritage of the successful performance of the Hard X-ray Detector (HXD) on board Suzaku satellite, enable to achive an extremely high background reduction for the cosmic-ray particle background and in-orbit activation. The current status of hardware development including the design requirement, expected performance, and technical readinesses of key technologies are summarized.

Since most gamma-ray bursts (GRBs) have a peak energy (Epeak) above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, a full understanding of the prompt emission from Swift GRBs requires spectral fits over as broad an energy range as possible. This can be done for bursts which are simultaneously detected by Swift BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV. Since the launch of Suzaku in July 2005, there have been 33 gamma-ray bursts (GRBs) which have triggered both Swift and WAM. A joint BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters including Epeak. The results of broad spectral fits allows us to understand the distribution of Epeak for Swift bursts and to calibrate Epeak estimators when Epeak is within the BAT energy range. For those bursts with spectroscopic redshifts, we can calculate the isotropic energy and study various correlations between Epeak and other global burst parameters. Here we present preliminary results of joint Swift/BAT-Suzaku/WAM spectral fits. © 2008 American Institute of Physics.

We present the results of the highest redshift GRB 050904 from joint spectral analyses among Swift/BAT, Konus-Wind and Suzaku-WAM covering a wide energy range of 15-5000 keV. The peak energy was first measured at 338 -93 +168keV, corresponding to 2465-678 +1225keV in the source frame. This is one of the highest value that has been ever meaured. The derived spectral and energetic parameters are consisitent with the Amati relation, but not with the Ghirlada relation. This implies that the circumburst density of this burst might be larger than the nominal value, as suggested by other wavelength observations. We also found that the burst could be an outlier in Yonetoku relation. © 2008 American Institute of Physics.

The SXS (Soft X-ray Spectrometer) onboard the coming Japanese X-ray satellite NeXT (New Exploration Xray Telescope) and the SXC (Spectrum-RC X-ray Calorimeter) in Spectrum-RG mission are microcalorimeter array spectrometers which will achieve high spectral resolution of similar to 6 eV in 0.3-10.0 keV energy band. These spectrometers are well-suited to address key problems in high-energy astrophysics. To achieve these high spectral sensitivities, these detectors require to be operated under 50 mK by using very efficient cooling systems including adiabatic demagnetization refrigerator (ADR,). For both missions, we propose a two-stage series ADR as a cooling system below 1 K, in which two units of ADR consists of magnetic cooling material, a superconducting magnet, and a heat switch are operated step by step. Three designs of the ADR are proposed for SXS/SXC. In all three designs, ADR can attain the required hold time of 23 hours at 50 mK and cooling power of 0.4 mu W with a low magnetic fields (1.5/1.5 Tesla or 2.0/3.0 Tesla) in a small configuration (180 mm phi x 319 mm in length). We also fabricated a new portable refrigerator for a, technology investigation of two-stage ADR. Two units of ADR have been installed at the bottom of liquid He tank. By using this dewar, important technologies such as an operation of two-stage cooling cycle, tight temperature control less than 1 mu K (in rms) stability, a, magnetic shielding, saltpills, and gas-gap heat switches are evaluated.

Results are presented of a Suzaku and Swift joint observation for an early X-ray afterglow of GRB 060105. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope (BAT) at 06:49:28 on 5 January 2006 (To). The Suzaku team commenced a pre-planned target of opportunity observation at 12:10 and continued till 12:00 on January 6. The X-ray flux faded during the observations from 6.8 x 10(-9) erg s(-1)cm(-2) to 1.5 x 10(-13) erg s(-1)cm(-2) in the 2-10 keV energy band. Following the prompt emission and successive "very steep decay", a "shallow decay" was observed from T-0 + 187 s to T-0 + 1287 s. After an observation gap during T-0 + (1.5 - 3) ks, an extremely early steep decay was observed in To + (4 - 30) ks. The steep decay exhibited decay indices of 2.3 - 2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below 1 degrees.

GRB 060105 was detected with the BAT instrument on-board Swift. The Suzaku follow-up observation started just 5.3 hours after the trigger with the XIS and HXD instruments. The XIS detected an uncatalogued fading source and its position was consistent with that previously reported by Swift XRT. We performed the spectral analyses using the data derived from Suzaku XIS and Swift XRT, and found that the spectrum of X-ray afterglow was well reproduced by the absorbed power law model. The best-fit spectral index and absorption are β = 2.15 ± 0.03 and NH = (3.74 ± 0.03) × 1021 cm-2, respectively. The observed decay curve by Suzaku XIS is fully consistent with the Swift XRT result. The Suzaku and Swift observations imply the possibility of the jet break at t = 3500 s, and the brightening of afterglow around t = 40000 s likely due to the refreshed shock. We see neither significant spectral evolution during the decay, nor evidence of emission line feature. © Società Italiana di Fisica.

Utilizing East Asian GRB Follow-up Observation Network (EAFON), we have obtained 3 major results; 1) first long-term monitoring of short GRB afterglow from similar to 0.1 days after the burst, 2) multi band monitoring of early optical shallow decay and re-brightening phase, 3) catch about 30 high-redshift GRB candidates. In this paper, we present shallow decay phase and re-brightening phase of early optical afterglow. Our results imply that these phases are unlikely to be caused by the variable external density model. Overall.1 day light curve behavior may be explained by Patchy shell model and/or different emission region such as 2 jets model rather than to be described by refreshed shock scenario.

The Lulin One-meter Telescope (LOT) has started GRBs follow-up since July 2003. In total, fifteen optical afterglows were detected successfully until July 2006. In this paper, we summarize these afterglows and two of them are described in detail. The two events are 1) GRB 040924, a GRB with cooling break and 2) GRB 050319, whose multi-color light curve shows different properties compared with Swift/XRT observations.

The WIDe-field telescope for Gamma-ray burst in Early Timing (WIDGET) is an automated optical telescope designed to detect the expected optical prompt emission associating with the Gamma-Ray Burst (GRBs). To search for the optical prompt emissions or possible pre-cursors, the system is programmed to track the HETE-2 and Swift field of views. The WIDGET has been operated since May 2004. So far, it succeeded 15 times to observe the GRB field at the same time of HETE-2 or Swift trigger and we succeeded to obtain the upper limits for the 7 GRBs.

In an XMM-Newton observation of the east lobe of nearby radio galaxy Fonrax A, we have significantly detected the diffuse X-ray emission, which was originally discovered by ASCA and ROSAT. The X-ray spectrum of the diffuse emission is described by a single powerlaw model, modified with the Galactic absorption toward the object. The best-fit X-ray photon index, 1.62(-0.15)(+0.25), agrees well with the synchrotron radio index, 1.68 +/- 0.05, between 29.9 MHz and 5 GHz. Therefore, the inverse Compton interpretation for the diffuse X-ray emission is justified. A comparison between the radio and Xray flux densities gives a moderate electron-energy dominance over in the east lobe of Fornax A, in spite of the dormancy of its nucleus. We also reexamined the ASCA result on the west lobe, to find that both lobes share the similar physical condition.

Suzaku is the fifth Japanese astrophysical satellite, devoted to study high energy phenomena in the X-ray band of 0.5 - 600 keV. It was successfully launched from Uchinoura Space Center in Japan on 10th July 2005. The HXD on board Suzaku covers 10 - 600 keV band with a high sensitivity of about 10(-5) cnt/s/cm(2)/keV level. The sensor consists of 16 identical GSO/BGO well-type-phoswich counters incorporating 2 mm-thick silicon PIN diodes, and 20 surrounding-BGO-shield counters to remove residual non X-ray backgrounds through anti-coincidence rejection. The present paper is particularly focused on timing system of the HXD and in-orbit verifications with pulsars.

The Hard X-ray Detector (HXD-II) is one of the three instruments onboard the Astro-E2 satellite scheduled for launch in 2005. The HXD-II consists of 16 main counters (Well units), surrounded by 20 active shield counters (Anti units). The Anti units have a large geometrical area of ∼ 800 cm2 with an uncollimated field of view covering ∼ 2π steradian. Utilizing 2.6 cm thick BGO crystals, they realize a large effective area of 400 cm 2 for 1 MeV photons. In the energy range of 300-5000 keV, the expected effective area is significantly larger than those of other gamma-ray burst instruments, such as CGRO/BATSE, HETE-2/FREGATE, and GLAST/GBM. Therefore, the Anti units act as a Wideband All-sky Monitor (WAM) for gamma-ray bursts in the energy range of 50-5000 keV. © Società Italiana di Fisica.

The Hard X-ray Detector (HXD) is one of the three instruments onboard Japanese X-ray astronomy satellite Astro-E2 scheduled for launch in 2005. This mission is very unique in a point of having a lower detector background than any other past missions in the 10-600 keV range. In the HXD, the large and thick BGO crystal are used as active shields for reducing the particle and gamma-ray background to the main detector. These anticoincidence shields are called as "Anti counters", which have a large geometrical area ∼ 800 cm 2 and an uncollimated field of view of ∼ 2π. Furthemore, they also have a larger effective area, corresponding to 400 cm 2 at even 1 MeV due to their thick high-Z materials. This feature enables us to observe the high energy radiation of Gamma-ray bursts with a higher sensitivity than previous all-sky monitors. Hence, the Anti counters have been developed as all-sky monitors with a broadband coverage of 50-5000 keV. In this paper, we will describe overall design of the HXD Anti counters, then report on the results of the pre-flight calibration test on June 2004 using the flight model. By irradiating various radio isotopes with Anti counters, we confirmed that they have capability as all-sky monitors. It is striking that the low energy threshold has been archived about 30 keV in spite of large volume of BGO scintillators. © 2004 IEEE.

We summarize significant improvements which have been achived in the development of Astro-E2 Hard X-ray Detector (HXD-II). An expanded energy range and better energy resolution have been achieved from progresses in device materials and redesigning of the front-end electronics. An improved estimation for the detector background in orbit has also been conducted based upon results from our proton irradiation experiment. The sensitivity of HXD-II can be expected to reach an order of 10(-6) [c s(-1) keV(-1) cm(-2)].

The Hard X-ray Detector (HXD-II) is one of the scientific payloads on board the fifth Japanese cosmic X-ray satellite Astro-E2, scheduled for launch in 2005. The HXD-II is designed to cover a wide energy range of 10 - 600 keV with a high sensitivity of ∼ 10-5 cnt/s/cm2/keV, using 16 identical GSO and BGO phoswich counters combined with 2 mm-thick silicon PIN diodes. In order to investigate the in-orbit performance of HXD-II in cosmic radiation environment, a Monte Carlo simulator based on the Geant4 toolkit is currently developed. There are two main goals of this simulator, which is directly connected to the detector's performance. One is to derive energy response to photons within the acceptance energy range, with 5% accuracy, after several types of standard event-selection of the HXD-II. The other is to estimate detector background with 10% accuracy. In addition to the background caused directly by the primary and secondary cosmic-rays, of particular importance is the radio-activation background induced by MeV protons trapped in the South Atlantic Anomaly. The simulator is also used in the pre-launch verifications of the HXD-II hardware. This paper describes the design concept of the Monte Carlo simulator, and its verification through comparison with the actual data of pre-flight radio-isotope irradiation experiments, together with calculated outputs that can demonstrate the in-orbit performance of the HXD-II. © 2004 IEEE.

The properties of 32k CdZnTe detectors have been studied in the pre-flight calibration of Burst Alert Telescope (BAT) on-board the Swift Gamma-ray Burst Explorer (scheduled for launch in January 2004). After corrections of the linearity and the gain, the energy resolution of summed spectrum is 7.0 keV (FWHM) at 122 keV. In order to construct response matrices for the BAT instrument, we extracted mobility-lifetime (mutau) products for electrons and holes in the CdZnTe. Based on a new method applied to Co-57 spectra taken at different bias voltages, mutau for electrons ranges from 5.0 x 10(-4) to 1.0 X 10(-2) cm(2)V(-1), while mutau for holes ranges from 1.0 x 10(-5) to 1.7 x 10(-4) cm(2)V(-1). We show that the distortion of the spectrum and the peak efficiency of the BAT instrument are well reproduced by the mutau database constructed in the calibration.

The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field-of-view (FOV), provides the gamma-ray burst triggers and locations for the Swift Gamma-Ray Burst Explorer. In addition to providing this imaging information, BAT will perform a 15 keV - 150 keV all-sky hard x-ray survey based on the serendipitous pointings resulting from the study of gamma-ray bursts, and will also monitor the sky for transient hard x-ray sources. For BAT to provide spectral and photometric information for the gamma-ray bursts, the transient sources and the all-sky survey, the BAT instrument response must be determined to an increasingly greater accuracy. This paper describes the spectral models and the ground calibration experiments used to determine the BAT response to an accuracy suitable for gamma-ray burst studies.

In addition to providing the initial gamma-ray burst trigger and location, the Swift Burst Alert Telescope (BAT) will also perform an all-sky hard x-ray survey based on serendipitous pointings resulting from the study of gamma-ray bursts. BAT was designed with a very wide field-of-view (FOV) so that it can observe roughly 1/7 of the sky at any time. Since gamma-ray bursts are uniformly distributed over the sky, the final BAT survey coverage is expected to be nearly uniform. BAT's large effective area and long sky exposures will produce a 15 - 150 keV survey with up to 30 times better sensitivity than any previous hard x-ray survey (e.g. HEAO A4). Since the sensitivity of deep exposures in this energy range is systematics limited, the ultimate survey sensitivity depends on the relative sizes of the statistical and systematic errors in the data. Many careful calibration experiments were performed at NASA/Goddard Space Flight Center to better understand the BAT instrument's response to 15-150 keV gamma-rays incident from any direction within the FOV. Using radioactive sources of gamma-rays with known locations and energies, the Swift team can identify potential systematic errors in the telescope's performance and estimate the actual Swift hard x-ray survey sensitivity in flight. These calibration results will be discussed and a preliminary parameterization of the BAT instrument response will be presented. While the details of the individual BAT CZT detector response will be presented elsewhere in these proceedings, this talk will focus on the translation of the calibration experimental data into overall hard x-ray survey sensitivity.

The gamma-ray burst (GRB) observatory Swift is now on the final stage of the prelaunch calibration to be launched in 2004. Swift is designed to observe GRBs and their afterglows with the burst alert telescope (BAT) and two multiwavelength telescopes (XRT and UVOT). The BAT, a coded mask hard X-ray telescope equipped with newly designed CdZnTe detectors, covers 1/6 sky to detect and determine the GRB position oriboard. With its sensitivity, it is calculated for the BAT to be able to detect more than 200 GRBs during its nominal two year mission life. The spacecraft maneuvers within about a minute to aim XRT and UVOT afterglows with their fine space and spectral resolutions. Swift is one of the ideal observatory to improve our knowledge by its capability of the continuous and multiwavelength observation. This paper also describes possible collaborations with X-ray and gamma-ray observatories including the coming ASTRO-E2.

Swift (Gehrels, 2000) is the Gamma Ray Bursts (GRBs) explorer, that is scheduled for launch in 2004. The Swift's major instrument Burst Alert Telescope (BAT) detector array sits Cadmium Zinc Telluride (CdZnTe, CZT) semiconductor devices under a coded mask. The array has 32,768 individual Cd0.9Zn0.1Te1.0 detectors (4x4 mm(2) large, 2mm thick) that have a total detector area of 5240 cm(2). CdZnTe materials are able to operate at room temperature for its large band gap, and also have a high average atomic number which makes them sensitive to hard X-rays (15similar to150 keV). We investigate energy response of the BAT detector for which to dedicate spectroscopy and imaging in observations of GRBs.

The Burst Alert Telescope (BAT) onboard the Swift Gamma-ray Burst Explorer (scheduled for launch in May of 2004) has a coded aperture mask and a detector array of 32,768 Cd0.9Zn0.1Te1.0 (4x4mm(2) large, 2mm thick) semiconductor devices. Due to small mobility and short lifetime of carriers, the electron-hole pairs generated by irradiation of gamma-rays cannot be completely collected. Since the shape of the measured spectra has the broad low-energy tail, it is very useful for us to estimate the obtained spectra to fit the model which considers the charge transport properties depended on the depth of the photon interaction (G.Sato, 2002) [1]. The energy calibration of the BAT array and coded mask experiments were carried out at NASA/Goddard Space Flight Center between December 2002 and March 2003. We applied the model fitting to the calibration spectra, to yield the mobility-lifetime products for each detector and these values differ by over 2 orders of magnitude among detectors. Also using the mobility-lifetime parameters, we can identified the detector energy response as a function of the temperature and illumination angle. But we figure out a difference between the model and the obtained data. To determine the difference between the model and the measured data, we conducted the detailed check experiment for a single CdZnTe, to show that the cause of the excess is due to the areal nonuniformity of the mobility-lifetime parameter.

The Burst Alert Telescope (BAT) onboard the Swift Gamma-ray Burst Explorer (scheduled for launch in May of 2004) has a coded aperture mask and a detector array of 32,768 Cd 0.9Zn 0.1Te 1.0 (4×4mm 2 large, 2mm thick) semiconductor devices. Due to small mobility and short lifetime of carriers, the electron-hole pairs generated by irradiation of gamma-rays cannot be completely collected. Since the shape of the measured spectra has the broad low-energy tail, it is very useful for us to estimate the obtained spectra to fit the model which considers the charge transport properties depended on the depth of the photon interaction (G.Sato, 2002). The energy calibration of the BAT array and coded mask experiments were carried out at NASA/Goddard Space Flight Center between December 2002 and March 2003. We applied the model fitting to the calibration spectra, to yield the mobility-lifetime products for each detector and these values differ by over 2 orders of magnitude among detectors. Also using the mobility-lifetime parameters, we can identified the detector energy response as a fucntion of the temperature and illumination angle. But we figure out a difference between the model and the obtained data. To determine the difference between the model and the measured data, we conducted the detailed check experiment for a single CdZnTe, to show that the cause of the excess is due to the areal nonuniformity of the mobility-lifetime parameter.

ASCA observation of the northern outer lobe edge region of the radio galaxy Centaurus A, similar to 3.5degrees north of its nucleus, is reported. Excess hard X-ray emission is seen around RA 13(hz)26m00(s), Dec. -39degrees20'00" (J2000 coordinates), together with soft diffuse X-ray emission extending all over the field of view of the GIS (similar to 50 arcmin in diameter). The spectrum of the soft diffuse emission is well described by an optically thin thermal plasma model with temperature kT similar to 0.6 keV modified by Galactic absorption. This emission is thought to arise from the thermal plasma associated with the outer lobe of Centaurus A and which has a thermal pressure of similar to 5 x 10(-13) dyn cm(-2). The excess hard emission is likely to be diffuse, and its spectrum is well described with a power law model of photon index similar to 1.7 or a thermal bremsstrahlung model of temperature kT greater than or similar to 11 keV. The nature of the hard emission is still unclear.

The energy-dependent response of the crystalline oxide scintillator Gd2SiO5:Ce3+ (GSO:Ce) is studied in the energy range from 14 to 662 keV as a part of the preflight calibration of the hard X-ray detector (HXD) onboard the ASTRO-E satellite. In the relation between photon energy deposited and light yields, there exists nonproportionality and discontinuity around the energy of the gadolinium K-edge (50.2 keV). In 16 GSO scintillator units of the HXD flight model, the same characteristics of the energy response are confirmed. To evaluate the response across the K-edge quantitatively, we measure the electron response" by means of the Compton coincidence technique. By using the electron response of the GSO crystal, we calculate the light yield nonproportionality as a function of deposited photon energy. We find that a photopeak line profile of the 59.5-keV emission of Am-241 is well modeled by a composite Gaussian. This will be discussed in terms of the light yield nonproportionality."

ASCA results are presented of extended X-rays from radio lobes of PKS B2356-601 and surrounding the cluster of galaxies Abell 4067. Obtained X-ray spectrum from the lobes allows two possibilities as its origin, those are a thin thermal plasma emission associated with one of lobes or an inverse-Compton (IC) emission by the relativistic electrons in the lobe. The paper presents a discussion on the origin and pressures of the lobe electrons and the surrounding intra-cluster medium.

A brief description is made of the HXD-II instrument, which is to be onboard the Astro-E2 mission to substitute the HXD (Hard X-ray Detector) instrument onboard the lost Astro-E.

The energy densities of electrons and magnetic fields, u(e) and u(m) respectively, are calculated for lobes of four radio galaxies from which the inverse Compton X-rays are detected. A tendency of u(e) > u(m) is found. Relations are examined between the core luminosity of radio galaxies and u(e) or u(m) in the lobes. We found that the ratio of u(e) to u(m) increases when the core becomes more active.

The Burst Alert Telescope (BAT) on the Swift gamma-ray burst mission will perform the first new all sky hard x-ray survey since 1977. BAT is a coded aperture instrument with 17 arcminute pixels and a 2 ster partially coded field of view. The imaging area has 32768 CdZnTe detectors, each 4X4X2 mm, with a total area of 5243 cm(2). Swift will perform pointings covering >64% of the sky each day and achieve an integrated sensitivity in three years of 0.6 milliCrabs for sources well off the Galactic plane. This survey is expected to identify hundreds of new highly obscured AGN.

The nearly final in-orbit calibration of the GIS, installed on the focal plane of the X-ray astronomy satellite ASCA, are summarized. With the successive in-orbit calibration with celestial sources and comparison with the results from the SIS, the GIS team and ASCA-GOF performed fine recalibration resulting released four and a newly presented final versions energy response matrices in collaboration with the XRT, SIS and ASCA operation teams.

We collected all light curves of the TeV blazar PKS 2155-304, spanning over 12 years, obtained by both Ginga and ASCA. Taking the advantage that Ginga covers a higher energy range compared to ASCA, we confirmed the amplitude of the variations being larger at higher energies, which is consistent with the synchrotron picture of the X-ray jet. We also report on the recent ASCA continuous 10-day observation of this source. In spite of its low flux compared to previous observations, we detected significant daily variations, and found that there was actually no particular quiescent period throughout our observation.

The ASTRO-E Hard X-ray Detector utilizes GSO/BGO well-type phoswich counters in compound-eye configuration, to achieve an extremely low background level of about a few times 10-5 counts s-1 cm-2 keV-1. The GSO scintillators placed at the bottom of the BGO well observe photons in the energy range 30-600 keV. To cover the lower energy range of 10-60 keV, silicon PIN diodes of 2 mm in thickness and 21.5 × 21.5mm2 in size were newly developed, and placed in front of the GSO scintillators. The PIN diode exhibits complex spectral responses, including subpeak and low energy tail components. To examine the origin of these components, we measured spatially-resolved response of the PIN diode, and confirmed that the subpeak and the low energy tail are related to the electrode structures and electric fields in the PIN diode, respectively.

A summary is presented of ASCA (Tanaka ct al. 1994) results on inverse-Comptonized X-rays from lobes of radio galaxies, which are emitted when relativistic electrons constructing synchrotron radio lobes boost up the cosmic microwave background photons to the X-ray and gamma-ray energy. By comparing the two radiation fluxes, we derived the energy distribution between magnetic fields and the relativistic electrons, assuming the same relativistic electrons in the lobes produce the emissions. This method is essentially free from the energy equipartition assumption. A study on spatial distributions of the field and particle energy densities is also presented. Based on the results presented in this paper, we suggest particle domination in the lobes and at the formation of the lobe.

We present multiband data for 18 blazars observed with ASCA, half of which were also observed contemporaneously with EGRET as parts of multi-wavelength campaigns. The ASCA X-ray spectra of High-energy peaked BL Lacs (HBLs) are soft, and they form the highest energy tail of the low energy (synchrotron) component. The X-ray spectra of the quasar-hosted blazars (QHBs) are hard and consistent with the lowest energy end of the high energy (HE, Compton) component. For Low-energy peaked BL Lacs (LBLs), the X-ray spectra are intermediate. We find that the radiation process responsible for the HE peak for HBLs can be explained solely by Synchrotron-Self-Compton (SSC) emission. For many QHBs, on the other hand, the gamma-rays cannot be solely due to the SSC mechanism. We consider an alternative scenario for QHBs where the SSC component dominates in the X-ray band, but it is below the observed gamma-ray spectrum. We infer the magnetic field to be 0.1 - 1 Gauss, and Lorentz factors of electrons radiating at the peak of the vF(v) spectrum of 10(3) for QHBs. This is much lower than 10(5) for HBLs. This difference is most likely due to the large photon density expected in QHBs.