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arXiv 1902.08358astro-ph.HE
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2018年磁星XTE J1810-197的X射线和射电爆发

The 2018 X-ray and Radio Outburst of Magnetar XTE J1810-197

E. V. Gotthelf, J. P. Halpern, J. A. J. Alford, T. Mihara, H. Negoro, N. Kawai, S. Dai, M. E. Lower, S. Johnston, M. Bailes, S. Oslowski, F. Camilo, H. Miyasaka, K. K. Madsen

摘要:

我们提出了XTE J1810-197 2018年爆发的最早X射线观测结果,这是自2003年发现以来的第一次爆发,是典型的瞬态和无线电发射异常X射线脉冲星(AXP)。全天空X射线图像监视器(MAXI)在11月20日至26日的可见度间隙之后立即检测到XTE J1810-197,与其作为无线电脉冲星的重新激活同时,于12月8日首次观察到。12月13日,核光谱望远镜阵列(NUSTAR)探测到至少30 keV的X射线发射,其光谱由黑体加幂律模型(温度kT = 0.74+/-0.02 keV和光子指数Gamma = 4.4+/-0.2)或双黑体模型(kT = 0.59+/-0.04 keV和kT = 1.0+/-0.2)充分表征0.1 keV,两者都包括额外的幂律分量以解释10 keV以上的发射,其中Gamma_h = -0.2+/-1.5和Gamma_h = 1.5+/-0.5。后者的指数是一致的硬X射线通量报告的非瞬态磁星。在2-10 keV的带通中,吸收通量为2 E-10 erg/s/cm ^2,比2003年爆发外推的最大通量大2倍。正弦X射线脉冲的峰值比无线电脉冲滞后约100秒。0.13周期,与2003年爆发期间的相位关系一致。这表明了一种稳定的几何结构,其中无线电发射起源于磁场线,该磁场线包含加热中子星表面一个点的电流。然而,测量的脉冲X射线的能量相关相移表明,所有X射线发射区域不是精确地共同对准的。

英文摘要:

We present the earliest X-ray observations of the 2018 outburst of XTE J1810-197, the first outburst since its 2003 discovery as the prototypical transient and radio-emitting anomalous X-ray pulsar (AXP). The Monitor of All-sky X-ray Image (MAXI) detected XTE J1810-197 immediately after a November 20-26 visibility gap, contemporaneous with its reactivation as a radio pulsar, first observed on December 8. On December 13 the Nuclear Spectroscopic Telescope Array (NUSTAR) detected X-ray emission up to at least 30 keV, with a spectrum well-characterized by a blackbody plus power-law model with temperature kT = 0.74+/-0.02 keV and photon index Gamma = 4.4+/-0.2 or by a two-blackbody model with kT = 0.59+/-0.04 keV and kT = 1.0+/-0.1 keV, both including an additional power-law component to account for emission above 10 keV, with Gamma_h = -0.2+/-1.5 and Gamma_h = 1.5+/-0.5, respectively. The latter index is consistent with hard X-ray flux reported for the non-transient magnetars. In the 2-10 keV bandpass, the absorbed flux is 2E-10 erg/s/cm^2, a factor of 2 greater than the maximum flux extrapolated for the 2003 outburst. The peak of the sinusoidal X-ray pulse lags the radio pulse by approx. 0.13 cycles, consistent with their phase relationship during the 2003 outburst. This suggests a stable geometry in which radio emission originates on magnetic field lines containing currents that heat a spot on the neutron star surface. However, a measured energy-dependent phase shift of the pulsed X-rays suggests that all X-ray emitting regions are not precisely co-aligned.

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