Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-ray Emission Profiles

We present results of 120 ks observation of a compact group of galaxies HCG~62 ($z=0.0145$) with Suzaku XIS and HXD-PIN\@. The XIS spectra for four annular regions were fitted with two temperature {\it vapec} model with variable abundance, combined with the foreground Galactic component. The Galactic component was constrained to have a common surface brightness among the four annuli, and two temperature {\it apec} model was preferred to single temperature model. We confirmed the multi-temperature nature of the intra-group medium reported with Chandra and XMM-Newton, with a doughnut-like high temperature ring at radii 3.3--6.5$'$ in a hardness image. We found Mg, Si, S, and Fe abundances to be fairly robust. We examined the possible ``high-abundance arc'' at $\sim 2'$ southwest from the center, however Suzaku data did not confirm it. We suspect that it is a misidentification of an excess hot component in this region as the Fe line. Careful background study showed no positive detection of the extended hard X-rays previously reported with ASCA, in 5--12 keV with XIS and 12--40 keV with HXD-PIN, although our upper limit did not exclude the ASCA result. There is an indication that the X-ray intensity in $r<3.3'$ region is $70\pm 19$% higher than the nominal CXB level (5--12 keV), and Chandra and Suzaku data suggest that most of this excess could be due to concentration of hard X-ray sources with an average photon index of $\Gamma=1.38\pm 0.06$. Cumulative mass of O, Fe and Mg in the group gas and the metal mass-to-light ratio were derived and compared with those in other groups. Possible role of AGN or galaxy mergers in this group is also discussed.Comment: 29 pages with 9 figures, accepted for publication in PASJ Vol 60, second Suzaku special issu

Suzaku observations of the Hydra A cluster out to the virial radius

We report Suzaku observations of the northern half of the Hydra A cluster out to ~1.4 Mpc, reaching the virial radius. This is the first Suzaku observations of a medium-size (kT ~3 keV) cluster out to the virial radius. Two observations were conducted, north-west and north-east offsets, which continue in a filament direction and a void direction of the large-scale structure of the Universe, respectively. The X-ray emission and distribution of galaxies elongate in the filament direction. The temperature profiles in the two directions are mostly consistent with each other within the error bars and drop to 1.5 keV at 1.5 r_500. As observed by Suzaku in hot clusters, the entropy profile becomes flatter beyond r_500, in disagreement with the r^1.1 relationship that is expected from accretion shock heating models. When scaled with the average intracluster medium (ICM) temperature, the entropy profiles of clusters observed with Suzaku are universal and do not depend on system mass. The hydrostatic mass values in the void and filament directions are in good agreement, and the Navarro, Frenk, and White universal mass profile represents the hydrostatic mass distribution up to ~ 2 r_500. Beyond r_500, the ratio of gas mass to hydrostatic mass exceeds the result of the Wilkinson microwave anisotropy probe, and at r_100, these ratios in the filament and void directions reach 0.4 and 0.3, respectively. We discuss possible deviations from hydrostatic equilibrium at cluster outskirts. We derived radial profiles of the gasmass- to-light ratio and iron-mass-to-light ratio out to the virial radius. Within r_500, the iron-mass-to-light ratio of the Hydra A cluster was compared with those in other clusters observed with Suzaku.Comment: 16 pages, 15 figures; Accepted for publication in PAS

Naïve rat umbilical cord matrix stem cells significantly attenuate mammary tumor growth through modulation of endogenous immune responses

Background: Un-engineered human and rat umbilical cord matrix stem cells (rUCMSC) attenuate growth of several types of tumors in mice and rats. However, the mechanism by which UCMSC attenuate tumor growth has not been studied rigorously. Methods- The possible mechanisms of tumor growth attenuation by rUCMSC were studied using orthotopic Mat B III rat mammary tumor grafts in female F344 rats. Tumor-infiltrating leukocytes were identified and quantified by immunohistochemical image analysis. Potential cytokines involved in lymphocyte infiltration in the tumors were determined by microarray and Western blot analysis. The Boyden chamber migration assay was performed for the functional analysis of identified cytokines. Results: rUCMSC markedly attenuated the tumor growth; this attenuation was accompanied by considerable lymphocyte infiltration. Immunohistochemical analysis revealed that the majority of infiltrating lymphocytes in the rUCMSC-treated tumors were CD3+ T cells. In addition, treatment with rUCMSC significantly increased infiltration of CD 8+ and CD4+ T cells and NK cells throughout tumor tissue. CD68+ monocytes/macrophages and FoxP3+ regulatory T cells were scarcely observed, only in the tumors of the PBS control group. Microarray analysis of rUCMSC identified that monocyte chemotactic protein (MCP)-1 is involved in rUCMSCinduced lymphocyte infiltration in the tumor tissues. Discussion: These results suggest that naïve rUCMSC attenuated mammary tumor growth at least in part by enhancing host anti-tumor immune responses. Thus, naïve UCMSC can be used as powerful therapeutic cells for breast cancer treatment, and MCP-1 may be a key molecule to enhance the effect of UCMSC at the tumor site

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国際教育部門 日本語研修コース / 深見兼孝 31 日本語・日本事情 (2016年4月～2017年3月) / 田村泰男 34 留学生関係科目 (2016年4月～2017年3月) / 田村泰男 48 第31期(2015－2016) 日本語・日本文化研修プログラム / 石原淳也 60 第17期平成28年度（2016年度）日韓共同理工系学部留学生事業入学前予備教育 / 石原淳也 63 広島大学短期交換留学（HUSA）プログラム / 恒松直美・堀田泰司 66 日本語・日本文化特別研修（中国）（台湾）（アジア非漢字圏）（専門）、中国語・中国文化特別研修、華語・台湾文化特別研修 / 本田義央 79 研究・その他の活動 8