Outflow-dominated Emission from the Quiescent Massive Black Holes in NGC 4621 and NGC 4697
Outflow-dominated Emission from the Quiescent Massive Black Holes in NGC 4621 and NGC 4697
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DOI：
10.1086/527542
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发表时间：
2007-12
期刊：
影响因子：
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通讯作者：
J. Wrobel;Y. Terashima;L. Ho
中科院分区：
文献类型：
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作者：
J. Wrobel;Y. Terashima;L. Ho
附近的椭圆星系NGC4621和NGC4697分别拥有一个M·>；108M☉的超大质量黑洞。对Chandra档案数据和新的NRAO甚大阵列数据的分析表明，每个星系都包含一个低光度活动星系核(LLAGN)，它被认为是一个微弱的硬X射线源，与微弱的8.5 GHz源在天文测量上是一致的。后者的直径小于0.3“(NGC 4621为26PC，NGC 4697为17PC)。激发这些LLAGNs的黑洞具有爱丁顿比L(2-10keV)/L(EDD)∼10−9，使它们处于所谓的静止区域。这些静态黑洞的辐射是射电响亮的，其对数RX=LOGνLν(8.5千兆赫)/L(2-10keV)∼−2，表明存在射电外流。此外，将袁和崔的射电-X射线-质量关系应用于静态黑洞，预测了观测到的射电光度νLν(8.5 GHz)在几倍之内。值得注意的是，这种关系是从流出而不是从吸积流中发出X射线。因此，这两个大质量黑洞发出的微弱但可探测到的辐射与外流占主导地位是一致的。建议对这一发现进行观察性测试。
The nearby elliptical galaxies NGC 4621 and NGC 4697 each host a supermassive black hole with M• > 108 M☉. Analysis of archival Chandra data and new NRAO Very Large Array data shows that each galaxy contains a low-luminosity active galactic nucleus (LLAGN), identified as a faint, hard X-ray source that is astrometrically coincident with a faint 8.5-GHz source. The latter has a diameter less that 0.3″ (26 pc for NGC 4621, 17 pc for NGC 4697). The black holes energizing these LLAGNs have Eddington ratios L(2–10 keV)/L(Edd) ∼ 10−9, placing them in the so-called quiescent regime. The emission from these quiescent black holes is radio-loud, with log RX = log ν Lν(8.5 GHz)/L(2–10 keV) ∼ − 2, suggesting the presence of a radio outflow. Also, application of the radio-X-ray-mass relation from Yuan & Cui for quiescent black holes predicts the observed radio luminosities ν Lν(8.5 GHz) to within a factor of a few. Significantly, that relation invokes X-ray emission from the outflow rather than from an accretion flow. The faint, but detectable, emission from these two massive black holes is therefore consistent with being outflow-dominated. Observational tests of this finding are suggested.