Testing the Low-Mass End of X-Ray Scaling Relations with a Sample of Chandra Galaxy Groups

Well-determined scaling relations between X-ray observables and cluster mass are essential for using large cluster samples for cosmology. Cluster relations such as the Lx-T, M-T, Lx-M relations, have been investigated extensively, however the question remains whether these relations hold true also for groups. Some evidence supports a break at low masses, possibly caused by the influence of non-gravitational physics on low-mass systems. The main goal of this work is to test scaling relations for the low-mass range to check whether there is a systematic difference between clusters and groups, and to extend this method of reliable cluster mass determination for future samples down to the group regime. We compiled a statistically complete sample of 112 X-ray galaxy groups, 26 with Chandra data. Temperature, metallicity, and surface brightness profiles were created, and used to determine the main physical quantities and scaling relations. We then compared the group properties to the HIFLUGCS clusters and other samples. We present profiles and scaling relations of the whole sample. T and Z profiles behave universally, except for the cores. The Lx-T, M-T, Lx-M, Mg-M, M-Yx, and Lx-Yx relations are in good agreement with clusters. The Lx-T relation steepens for T<3keV, which could point to a larger impact of heating mechanisms on cooler systems. We found a strong drop in the gas mass fraction below 1keV, which indicates the ICM is less dominant in groups and the galaxies have a stronger influence on the system. In all relations the intrinsic scatter for groups is larger, which appears not correlated with merger activity but could be due to scatter caused by baryonic physics in the group cores. We also demonstrate the importance of selection effects. We have found evidence for a similarity break between groups and clusters. However this does not have a strong effect on scaling relations.Comment: 31 pages, accepted to A&

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