A complex state transition from the black hole candidate swift J1753.5-0127
Monthly Notices of the Royal Astronomical Society 429:2 (2013) 1244-1257
Abstract:
We present our monitoring campaign of the outburst of the black hole candidate Swift J1753.5-0127, observed with the Rossi X-ray Timing Explorer and the Swift satellites. After ̃4.5 yr since its discovery, the source had a transition to the hard intermediate state. We performed spectral and timing studies of the transition showing that, unlike the majority of the transient black holes, the system did not go to the soft states but it returned to the hard state after a few months. During this transition Swift J1753.5-0127 features properties which are similar to those displayed by the black hole Cygnus X-1. We compared Swift J1753.5-0127 to one dynamically confirmed black hole and two neutron stars showing that its power spectra are in agreement with the binary hosting a black hole. We also suggest that the prolonged period at low flux that followed the initial flare is reminiscent of that observed in other X-ray binaries, as well as in cataclysmic variables. © 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Fast and slow rotators in the densest environments: A FLAMES/GIRAFFE integral field spectroscopy study of galaxies in a1689 at z = 0.183
Monthly Notices of the Royal Astronomical Society 429:2 (2013) 1258-1266
Abstract:
We present FLAMES/GIRAFFE integral field spectroscopy of 30 galaxies in the massive cluster A1689 at z = 0.183. Conducting an analysis similar to that of ATLAS3D, we extend the baseline of the kinematic morphology-density relation by an order of magnitude in projected density and show that it is possible to use existing instruments to identify slow and fast rotators beyond the local Universe. We find 4.5 ± 1.0 slow rotators with a distribution in magnitude similar to those in the Virgo cluster. The overall slow rotator fraction of our A1689 sample is 0.15 ± 0.03, the same as in Virgo using our selection criteria. This suggests that the fraction of slow rotators in a cluster is not strongly dependent on its density. However, within A1689, we find that the fraction of slow rotators increases towards the centre, as was also found in the Virgo cluster. © 2012 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Measurement of W-boson polarization in top-quark decay using the full CDF Run II data set
Physical Review D - Particles, Fields, Gravitation and Cosmology 87:3 (2013)
Abstract:
We measure the polarization of W bosons from top-quark (t) decays into final states with a charged lepton and jets, tt̄→W+bW -b̄→ℓνbqq̄′b̄, using the full Run II data set collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb-1. A model-independent method simultaneously determines the fraction of longitudinal (f0) and right-handed (f+) W bosons to yield f0=0.726±0. 066(stat)±0.067(syst) and f+=-0.045±0.044(stat) ±0.058(syst) with a correlation coefficient of -0.69. Additional results are presented under various standard model assumptions. No significant discrepancies with the standard model are observed. © 2013 American Physical Society.Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs
Physical Review Letters 110:8 (2013)
Abstract:
A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb-1, collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or μ pairs, is 126.2±0.6(stat) ±0.2(syst) GeV. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis. © 2013 CERN. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Measurement of the υ(1S), υ(2S), and υ(3S) polarizations in pp collisions at √s=7 TeV
Physical Review Letters 110:8 (2013)