Discovery of a New Supernova Remnant in the Direction of G69.7+1.0

We discovered a middle-aged supernova remnant (SNR) in the vicinity of G69.7+1.0 using the ASCA satellite. G69.7+1.0 was identified in the 2.7 GHz survey and classified as a shell-type SNR with a diameter of 16 arcmin. During the ROSAT all-sky survey, the X-ray emission was detected in the direction of G69.7+1.0. However, it extends beyond the radio shell, and an X-ray bright region was located outside of the radio shell. A spectral study with the ASCA and ROSAT shows a thin thermal plasma with an electron temperature of ~0.4 keV. There is no significant variation of the spectral parameters over the field of view, except for the lower column density of the eastern part. We also found a large shell structure which surrounds the X-ray bright region in both optical and radio images. We suggest that the observed X-ray emission is associated with the large optical and radio shell, and that they are part of a new SNR, different from the radio SNR G69.7+1.0, which we have named AX J2001+3235 or G69.4+1.2. The large shell and the electron temperature of ~0.4 keV indicate that AX J2001+3235 is an evolved SNR. From a comparison with the column density of CTB 80 (G69.0+2.7), we estimate that the distance of the SNR is about 2.5 kpc.Comment: Accepted for publication in PASJ, 9 pages, 5 figure

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

The Cygnus Loop was observed from the northeast to the southwest with XMM-Newton. We divided the observed region into two parts, the north path and the south path, and studied the X-ray spectra along two paths. The spectra can be well fitted either by a one-component non-equilibrium ionization (NEI) model or by a two-component NEI model. The rim regions can be well fitted by a one-component model with relatively low \kTe whose metal abundances are sub-solar (0.1--0.2). The major part of the paths requires a two-component model. Due to projection effects, we concluded that the low kTe (about 0.2 keV) component surrounds the high kTe (about 0.6 keV) component, with the latter having relatively high metal abundances (about 5 times solar). Since the Cygnus Loop is thought to originate in a cavity explosion, the low-kTe component originates from the cavity wall while the high-kTe component originates from the ejecta. The flux of the cavity wall component shows a large variation along our path. We found it to be very thin in the south-west region, suggesting a blowout along our line of sight. The metal distribution inside the ejecta shows non-uniformity, depending on the element. O, Ne and Mg are relatively more abundant in the outer region while Si, S and Fe are concentrated in the inner region, with all metals showing strong asymmetry. This observational evidence implies an asymmetric explosion of the progenitor star. The abundance of the ejecta also indicates the progenitor star to be about 15 M_sun.Comment: 24 pages, 9 figures, Astrophysical Journal in pres

Overabundance of Calcium in the young SNR RX J0852−-4622: evidence of over-production of 44^{44}Ti

Recently, COMPTEL has detected $\gamma$-rays of 1157 keV from $^{44}$Ti in the direction of the SNR RX J0852$-$4622 (Iyudin et al. 1998). Since $^{44}$Ti is a product of explosive nucleosynthesis and its half lifetime \tau\sb{1/2} is about 60 yrs, RX J0852$-$4622 must be a young supernova remnant and radiation is dominated by the ejecta rather than by interstellar matter. We have detected an X-ray emission line at $4.1\pm 0.2$ keV which is thought to come from highly ionized Ca. The emission line is so far only seen in the north-west shell region of RX J0852$-$4622. The X-ray spectrum can be well fitted with that of thin hot plasma of cosmic abundances except that of Ca, which is overabundant by a factor of $8 \pm 5$. Assuming that most of Ca is $^{44}$Ca, which originates from $^{44}$Ti by radioactive decay, we estimate a total Ca mass of about $1.1\times 10^{-3}M_\odot$. Combining the amount of $^{44}$Ca and the observed flux of the $^{44}$Ti $\gamma$-ray line, the age of RX J0852$-$4622 is around 1000 yrs.Comment: 14 pages, 5figures, accepted for publication of PAS

Chandra Observations of the Northeastern Rim of the Cygnus Loop

We present results from spatially resolved spectral analyses of the northeastern (NE) rim of the Cygnus Loop supernova remnant (SNR) based on two Chandra observations. One pointing includes northern outermost abundance-enhanced regions discovered by recent Suzaku observations, while the other pointing is located on regions with "normal" abundances in the NE rim of the Cygnus Loop. The superior spatial resolving power of Chandra allows us to reveal that the abundance-enhanced region is concentrated in an about 200"-thickness region behind the shock front. We confirm absolute metal abundances (i.e., relative to H) as well as abundance ratios between metals are consistent with those of the solar values within a factor of about 2. Also, we find that the emission measure in the region gradually decreases toward the shock front. These features are in contrast with those of the ejecta fragments around the Vela SNR, which leads us to believe that the abundance enhancements are not likely due to metal-rich ejecta. We suggest that the origin of the plasma in this region is the interstellar medium (ISM). In the "normal" abundance regions, we confirm that abundances are depleted to the solar values by a factor of about 5 that is not expected in the ISM around the Cygnus Loop. Introduction of non-thermal emission in our model fitting can not naturally resolve the abundance-depletion problem. The origin of the depletion still remains as an open question.Comment: 18 pages, 6 figure

Performance of a newly developed SDCCD for X-ray use

A Scintillator Deposited CCD (SDCCD) is a wide-band X-ray detector consisting of a CCD and a scintillator directly attached to each other. We assembled the newly developed SDCCD that the scintillator CsI(Tl) is below the fully depleted CCD. The incident X-rays enter the CCD depletion layer first. Then, X-rays passing through the depletion layer are absorbed in the CsI(Tl). The contact surface of the CCD is a back-illuminated side so that we can have good light collection efficiency. In our experimental setup, we confirmed good performance of our SDCCD detecting many emission lines up to 88\,keV that comes from $^{109}$Cd.Comment: 4 pages, 6 figures, accepted publication for Nucl. Instr. and Meth. (2010

On the Nature of AX J2049.6+2939 and AX J2050.0+2914

AX J2049.6+2939 is a compact X-ray source in the vicinity of the southern blow-up region of the Cygnus Loop supernova remnant (Miyata et al. 1998a). This source was the brightest X-ray source inside the Cygnus Loop observed during the ASCA survey project. The X-ray spectrum was well fitted by a power-law function with a photon index of $-2.1 \pm 0.1$. Short-term timing analysis was performed and no coherent pulsation was found. Follow-up observations with ASCA have revealed a large variation in X-ray intensity by a factor of $\simeq$ 50, whereas the spectral shape did not change within the statistical uncertainties. In the second ASCA observation, we found another X-ray source, AX J2050.0+2941, at the north east of AX J2049.6+2939. During the three ASCA observations, the X-ray intensity of AX J2050.0+2941 varied by a factor of $\simeq$4. No coherent pulsations could be found for AX J2050.0+2941. We have performed optical photometric and spectroscopic observations in the vicinity of AX J2049.6+2939 at the Kitt Peak National Observatory (KPNO). As a result, all objects brighter than $B$-band magnitude of 22 in the error box can be identified with normal stars. Combined with the X-ray results and the fact that there are no radio counterparts, AX J2049.6+2939 is not likely to be either an ordinary rotation-powered pulsar or an AGN. The nature of AX J2049.6+2939 is still unclear and further observations over a wide energy band are strongly required. As to AX J2050.0+2941, the long-term X-ray variability and the radio counterpart suggests that it is an AGN.Comment: 23 pages, 4 figures, Accepted for publication by Astrophysical Journa

Physicochemical inactivation of zoonotic Viruses: Hemorrhagic fever with renal syndrome and lymphocytic choriomeningitis Viruses

To seek the most effective and practical methods of disinfecting and for inactivating two zoonotic viruses, hemorrhagic fever with renal syndrome virus (HFRSV) and lymphocytic choriomeningitis virus (LCMV), we analysed inactivation of the viruses by 8 commonly-used chemical disinfectants and physical treatments. The results demonstrated that alcohols (70% ethanol, 50% isopropanol), formaldehyde (2% formalin), quaternary ammonium chloride (0.05% benzalkonium chloride) and 1% saponated cresol were virucidal on more than 99.9% of the infectious virus particles. HFRSV was more resistant than LCMV on several treatments. No significant difference was observed in strains of HFRSV. Quaternary ammonium chloride and saponated cresol diluted with hot water (>60°C), are considered to be the reagents of choice for disinfecting the two zoonotic viruses because of their long-term effectiveness and mild corrosive action to metals. Spraying of alcohols has proven to be a suitable means for decontaminating instruments, and experiments tools in limited areas of animal laboratorie

Proton Irradiation Experiment for the X-ray Charge-Coupled Devices of the Monitor of All-sky X-ray Image mission onboard the International Space Station: I. Experimental Setup and Measurement of the Charge Transfer Inefficiency

We have investigated the radiation damage effects on a CCD to be employed in the Japanese X-ray astronomy mission including the Monitor of All-sky X-ray Image (MAXI) onboard the International Space Station (ISS). Since low energy protons release their energy mainly at the charge transfer channel, resulting a decrease of the charge transfer efficiency, we thus focused on the low energy protons in our experiments. A 171 keV to 3.91 MeV proton beam was irradiated to a given device. We measured the degradation of the charge transfer inefficiency (CTI) as a function of incremental fluence. A 292 keV proton beam degraded the CTI most seriously. Taking into account the proton energy dependence of the CTI, we confirmed that the transfer channel has the lowest radiation tolerance. We have also developed the different device architectures to reduce the radiation damage in orbit. Among them, the ``notch'' CCD, in which the buried channel implant concentration is increased, resulting in a deeper potential well than outside, has three times higher radiation tolerance than that of the normal CCD. We then estimated the charge transfer inefficiency of the CCD in the orbit of ISS, considering the proton energy spectrum. The CTI value is estimated to be 1.1e-5 per each transfer after two years of mission life in the worse case analysis if the highest radiation-tolerant device is employed. This value is well within the acceptable limit and we have confirmed the high radiation-tolerance of CCDs for the MAXI mission.Comment: 17 pages, 2 table, 12 figures. Accepted for publication of Japanese Journal of Applied Physics. High resolution file is available from http://wwwxray.ess.sci.osaka-u.ac.jp/~miyata/paper/proton_cti.pd