@article{HamaguchiCorcoran2015,
  author    = {Hamaguchi, K. and Corcoran, M. F.},
  title     = {Extremely Hard X-ray Emission from η Car Observed with XMM-Newton and NuSTAR around Periastron in 2014.6},
  series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  journal   = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-87926},
  pages     = {159 -- 162},
  year      = {2015},
  abstract  = {The super massive binary system, η Car, experienced periastron passage in the summer of 2014. We observed the star twice around the maximum (forb =0.97, 2014 June 6) and just before the minimum (ϕorb =0.99, 2014 July 28) of its wind-wind colliding (WWC) X-ray emis-sion using the XMM-Newton and NuSTAR observatories, the latter of which is equipped with extremely hard X-ray (>10 keV) focusing mirrors. In both observations, NuSTAR detected the thermal X-ray tail up to 40-50 keV. The hard slope is consistent with an electron tem- perature of ∼6 keV, which is significantly higher than the ionization temperature (kT ∼4 keV) measured from the Fe K emission lines, assuming collisional equilibrium plasma. The spectrum did not show a hard power-law component above this energy range, unlike earlier detections with INTEGRAL and Suzaku. In the second NuSTAR observation, the X-ray flux above 5 keV declined gradually in ∼1 day. This result suggests that the WWC apex was gradually hidden behind the optically thick primary wind around conjunction.},
  language  = {en}
}
@article{RussellCorcoranCuadraetal.2015,
  author    = {Russell, C. M. P. and Corcoran, M. F. and Cuadra, J. and Owocki, S. P. and Wang, Q. D. and Hamaguchi, K. and Sugawara, Y. and Pollock, A. M. T. and Kallman, T. R.},
  title     = {Hydrodynamic and radiative transfer modeling of X-ray emission from colliding WR winds},
  series = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  journal   = {Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.-5. June 2015},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-88255},
  pages     = {309 -- 312},
  year      = {2015},
  abstract  = {Colliding Wolf-Rayet (WR) winds produce thermal X-ray emission widely observed by X-ray telescopes. In wide WR+O binaries, such as WR 140, the X-ray flux is tied to the orbital phase, and is a direct probe of the winds' properties. In the Galactic center, ~30 WRs orbit the super massive black hole (SMBH) within ~10", leading to a smorgasbord of wind-wind collisions. To model the X-ray emission of WR 140 and the Galactic center, we perform 3D hydrodynamic simulations to trace the complex gaseous flows, and then carry out 3D radiative transfer calculations to compute the variable X-ray spectra. The model WR 140 RXTE light curve matches the data well for all phases except the X-ray minimum associated with periastron, while the model spectra agree with the RXTE hardness ratio and the shape of the Suzaku observations throughout the orbit. The Galactic center model of the Chandra flux and spectral shape match well in the region r ≤ 3", but the model flux falls off too rapidly beyond this radius.},
  language  = {en}
}