| タイトル | Eta Carinae's Thermal X-Ray Tail Measured with XMM-Newton and NuStar |
| 本文（外部サイト） | http://hdl.handle.net/2060/20150023280 |
| 著者（英） | Stuhlinger, Martin; Yuasa, Takayuki; Moffat, Anthony F. J.; Corcoran, Michael F.; Madura, Thomas; Takahashi, Hiromitsu; Hamaguchi, Kenji; Russell, Christopher; Grefenstette, Brian; Gull, Theodore R. |
| 発行日 | 2016-01-19 |
| 言語 | eng |
| 内容記述 | The evolved, massive highly eccentric binary system, Car, underwent a periastron passage in the summer of 2014. We obtained two coordinated X-ray observations with XMM-Newton and NuSTAR during the elevated X-ray flux state and just before the X-ray minimum flux state around this passage. These NuSTAR observations clearly detected X-ray emission associated with eta Car extending up to approx. 50 keV for the first time. The NuSTAR spectrum above 10 keV can be fit with the bremsstrahlung tail from a kT approx. 6 keV plasma. This temperature is delta kT 2 keV higher than those measured from the iron K emission line complex, if the shocked gas is in collisional ionization equilibrium. This result may suggest that the companion star's pre-shock wind velocity is underestimated. The NuSTAR observation near the X-ray minimum state showed a gradual decline in the X-ray emission by 40% at energies above 5 keV in a day, the largest rate of change of the X-ray flux yet observed in individual eta Car observations. The column density to the hardest emission component, N(sub H) approx. 10(exp24) H cm(exp2), marked one of the highest values ever observed for eta Car, strongly suggesting the increased obscuration of the wind-wind colliding X-ray emission by the thick primary stellar wind prior to superior conjunction. Neither observation detected the power-law component in the extremely hard band that INTEGRAL and Suzaku observed prior to 2011. The power-law source might have faded before these observations. |
| NASA分類 | Astronomy |
| レポートNO | GSFC-E-DAA-TN26982 |
| 権利 | Copyright, Distribution under U.S. Government purpose rights |
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