Metal Abundances in the Hot Interstellar Medium in Early-Type Galaxies Observed with ASCA

We have analyzed ASCA data of 27 early-type galaxies, and studied the properties of their X-ray emitting ISM (Inter Stellar Medium) in detail. We found that overlapping lines and free-bound continuum cause strong coupling in the derived abundances of various elements. The abundance determination is also difficult due to the uncertainties in the Fe-L atomic physics, because Fe-L lines couple with O and Ne K-lines. However, when abundances of $\alpha$-elements are fixed, all the plasma codes give similar Fe abundances with a scattering of only 20-30%. To relax the strong coupling among the elements, we included 20% systematic errors in the Fe-L region of the spectra. Then, in X-ray luminous galaxies, the derived abundance of Fe and $\alpha$-elements both became $\sim 1$ solar within a factor of 2. This result relaxes the previous severe discrepancy between the ISM and stellar metallicities. The ISM metallicity in X-ray fainter galaxies is still uncertain, but we can at least constrain that contribution from type-Ia SN to the ISM abundance is lower than in X-ray luminous systems. These results strongly suggest that a large fraction of SN Ia products have escaped into intergalactic space.Comment: 48 pages with 20 figures, Latex(PASJadd.sty, PASJ95.sty), accepted for publication in PAS

ASCA Compilation of X-Ray Properties of Hot Gas in Elliptical Galaxies and Galaxy Clusters: Two Breaks in the Temperature Dependences

Utilizing ASCA archival data of about 300 objects of elliptical galaxies, groups, and clusters of galaxies, we performed systematic measurements of the X-ray properties of hot gas in their systems, and compiled them in this paper. The steepness of the luminosity--temperature (LT) relation, $L_{\rm X}\propto(kT)^{\alpha}$, in the range of $kT=$1.5--15 keV is $\alpha=3.17\pm0.15$, consistent with previous measurements. In the relation, we find two breaks at around ICM temperatures of 1 keV and 4 keV: $\alpha=2.34\pm0.29$ above 4 keV, $3.74\pm0.32$ in 1.5--5 keV, and $4.03\pm1.07$ below 1.5 keV. Such two breaks are also evident in the temperature and size relation. The steepness in the LT relation at $kT>4$ keV is consistent with the scale-relation derived from the CDM model, indicating that the gravitational effect is dominant in richer clusters, while poorer clusters suffer non-gravity effects. The steep LT relation below 1 keV is almost attributed to X-ray faint systems of elliptical galaxies and galaxy groups. We found that the ICM mass within the scaling radius $R_{1500}$ follows the relation of $M_{\rm gas}\propto T^{2.33\pm0.07}$ from X-ray faint galaxies to rich clusters. Therefore, we speculate that even such X-ray faint systems contain a large-scale hot gas, which is too faint to detect.Comment: 59 pages, 20 figures, to appear in PASJ 56 No.6 Pdf documents including complete tables are available as http://www-heaf.hepl.hiroshima-u.ac.jp/~fukazawa/icmmas-sup.pd

High Pressure Apparatus for Angle Dispersive Neutron Diffraction

A piston-cylinder type high pressure apparatus was designed for the angle dispersive neutron diffraction. A Ti-53wt% Zr alloy was used for the cylinder. The performance was tested by observing the structural transformation under pressure in RbBr from an NaCl-type to a CsCl-type

Detection of Excess Hard X-ray Emission from the Group of Galaxies HCG62

From the group of galaxies HCG62, we detected an excess hard X-ray emission in energies above $\sim 4$ keV with \A SCA. The excess emission is spatially extended up to $\sim10'$ from the group center, and somewhat enhanced toward north. Its spectrum can be represented by either a power-law of photon index 0.8-2.7, or a Bremsstrahlung of temperature $>6.3$ keV. In the 2-10 keV range, the observed hard X-ray flux, $(1.0\pm0.3)\times10^{-12}$ erg cm$^{-2}$ s$^{-1}$, implies a luminosity of $(8.0\pm2.0)\times10^{41}$ erg s$^{-1}$ for a Hubble constant of 50 km s$^{-1}$ Mpc$^{-1}$. The emission is thus too luminous to be attributed to X-ray binaries in the memb er galaxies. We discuss possible origin of the hard X-ray emission.Comment: 6 pages, 3 Postscript figures, uses emulateapj.sty. Accepted for publication in the Astrophysical Journal Letter

Development of the sensitizer for generating higher-energy photons under diluted condition via the triplet-triplet annihilation-supported upconversion

It was previously reported that photon upconversion can occur in the solution containing anthracene and the Pt complex of octaethylporphyrin (PtOEP) via the triplet-triplet annihilation process. In this study, by employing the modified Pt complex of the dual anthracene-tethered porphyrin, DA-PtP as a sensitizer, it is demonstrated that shorter-wavelength light can be generated under diluted condition. We synthesized DA-PtP and compared upconversion properties by changing the type of sensitizers. Accordingly, it was shown that the photon upconversion proceeded with the xenon lamp (540 nm) in the presence of DA-PtP. Furthermore, it was found that the emission band in the shorter wavelength light in the near UV region was observed from the solution containing DA-PtP even under diluted condition. From the mechanistic investigation, it was proposed that the anthracene moieties in DA-PtP might inhibit to form agglomeration with the free anthracene. As a result, reabsorption of the higher-energy light generated from upconversion could be suppressed

A High Pressure Apparatus for Neutron Diffraction

A high pressure apparatus was developed for thermal neutron diffraction of time-of-flight method. The high pressure vessel was a piston-cylinder type, and Ti-Zr alloy was used as a material of the cylinder. The coherent scattering of neutron is suppressed in Ti-53wt% Zr alloy. The diffraction spectrum is formed of peaks from the specimen and a background, which corresponds to the energy distribution of the incident neutron. High pressure measurements were made in RbBr on the transformation between NaCl-type structure and CsCl-type to a pressure about 20 kb, and a good agreement was confirmed with former experiments