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

Application of a novel gas phase synthesis approach to carbonyl complexes of accelerator-produced 5d transition metals

In 2014 the first synthesis of a transactinide carbonyl complex - seaborgium hexacarbonyl - was reported. This was achieved in gas-phase chemical experiments in a beam-free environment behind the recoil separator GARIS. Extending this work to heavier elements requires more efficient techniques to synthesize carbonyl complexes as production rates of transactinide elements drop with increasing atomic number. A novel approach was thus conceived, which retains the benefit of a beam-free environment but avoids the physical preseparation step. The latter reduces the yields for products of asymmetric reactions such as those used for the synthesis of suitable isotopes of Sg, Bh, Hs and Mt. For this a series of experiments with accelerator-produced radioisotopes of the lighter homologues W, Re and Os was carried out at the tandem accelerator of JAEA Tokai, Japan. A newly developed double-chamber system, which allows for a decoupled recoil ion thermalization and chemical complex formation, was used, which avoids the low-efficiency physical preseparation step. Here, we demonstrate the feasibility of this newly developed method using accelerator-produced short-lived radioisotopes of the 5d homologues of the early transactinides