THE DISCOVERY OF 8.7 SECOND PULSATIONS FROM THE ULTRASOFT X-RAY SOURCE 4U 0142+61
THE DISCOVERY OF 8.7 SECOND PULSATIONS FROM THE ULTRASOFT X-RAY SOURCE 4U 0142+61
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8.7 来自超软 X 射线源 4U 0142 61 的第二脉动的发现
DOI：
10.1086/187539
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
L. Stella
中科院分区：
文献类型：
--
作者：
G. Israel;S. Mereghetti;L. Stella
我们发现 X 射线源 4U0142+61 的周期性约为 8.7 秒，此前根据其超软光谱，该源被认为是可能的黑洞候选者。 1984 年 8 月利用 EXOSAT 卫星进行观测时，仅在 1--4 keV 能量范围内可见脉动。对轨道运动引起的脉冲到达时间延迟的搜索得到了负面结果。在相同的数据中，之前在 4 keV 以上的额外硬光谱成分中发现了 25 分钟的周期性振荡，该成分由 X 射线瞬变 RX J0146.9+6121 产生，由 ROSAT 发现并用 Be 星识别。虽然 4U0142+61 非常高（>10^4）的 X 射线与光通量比与基于孤立中子星的模型兼容，但最简单的解释涉及一个低质量 X 射线双星，其伴星非常微弱，类似于 4U1626--67。 4U0142+61 周期性脉动的发现削弱了超软光谱分量是吸积黑洞特征的现象学标准。
We discovered a periodicity at about 8.7s from the X--ray sources 4U0142+61, previously considered a possible black hole candidate on the basis of its ultrasoft spectrum. The pulsations are visible only in the 1--4 keV energy range, during an observation obtained with the EXOSAT satellite in August 1984. A search for delays in the pulse arrival times caused by orbital motion gave negative results. In the same data, periodic oscillations at 25 minutes had been previously found in an additional hard spectral component dominating above 4 keV which arises from the X-ray transient RX J0146.9+6121, discovered with ROSAT and identified with a Be star. Though the very high (>10^4) X--ray to optical flux ratio of 4U0142+61 is compatible with models based on an isolated neutron star, the simplest explanation involves a low mass X--ray binary with a very faint companion, similar to 4U1626--67. The discovery of periodic pulsations from 4U0142+61 weakens the phenomenological criterion that an ultrasoft spectral component is a signature of accreting black holes.