...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >High-frequency excess in the radio continuum spectrum of the type-1 Seyfert galaxy NGC985
【24h】

High-frequency excess in the radio continuum spectrum of the type-1 Seyfert galaxy NGC985

机译：1型塞弗特星系NGC985的无线电连续谱中的高频过量

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The Seyfert galaxy NGC985 is known to show a high-frequency excess in its radio continuum spectrum at a milli-Jansky level on the basis of previous observations at 1.4-15 GHz; a steep spectrum at low frequencies (a spectral index, alpha = -1.10 +/- 0.03) changes at similar to 10 GHz into an inverted spectrum at higher frequencies (alpha = +0.86 +/- 0.09). We conduct new observations at 15-43 GHz using the Very Large Array and at 100 GHz using the Nobeyama Millimeter Array. As a result, the high-frequency excess has been confirmed as continuing at even higher radio frequencies, up to 43 GHz. The non-detection at 100 GHz was not so strong a constraint, and therefore the spectral behavior above 43 GHz remains unclear. The astrometric position of the high-frequency excess component coincides with the optical position of the Seyfert nucleus and the low-frequency radio position to an accuracy of 0.'' 1, corresponding to similar to 80 pc; the radio source size is constrained to be <0.'' 02, corresponding to <16 pc. We discuss the physical origin of the observed high-frequency excess component. Dust emission at the Rayleigh-Jeans regime, free-free emission from X-ray radiating high-temperature plasma, free-free emission from the ensemble of broad-line region clouds, or thermal synchrotron from hot accretion flow cannot be responsible for the observed radio flux. Compact jets under synchrotron self-absorption may be unlikely in terms of observed time scales. Alternatively, we cannot rule out the hypotheses of synchrotron jets free-free absorbed by a circumnuclear photoionized region, and self-absorbed nonthermal synchrotron from disk corona, as the origin of the high-frequency excess component.
机译：根据先前在1.4-15 GHz的观测结果，塞弗特星系NGC985在毫连续级的无线电连续谱中显示出高频过量;低频下的陡峭频谱（频谱指数，α= -1.10 +/- 0.03）在类似于10 GHz的频率下变为高频下的倒频谱（α= +0.86 +/- 0.09）。我们使用甚大型阵列在15-43 GHz处以及使用Nobeyama毫米阵列在100 GHz处进行新观测。结果，已经确认了高频过量在高达43 GHz的更高射频下仍在继续。在100 GHz处的非检测不是很强的约束，因此不清楚在43 GHz以上的频谱行为。高频多余分量的天体位置与塞弗特核的光学位置和低频无线电位置重合，精度为0''1，相当于80 pc;无线电源尺寸被限制为<0''。02，对应于<16 pc。我们讨论了观察到的高频多余分量的物理起源。 Rayleigh-Jeans态下的粉尘排放，X射线辐射高温等离子体的自由自由排放，宽线区域云集合的自由自由排放，或热积聚流产生的热同步加速器均不能引起观测。无线电通量。就观察到的时间尺度而言，在同步加速器自吸收下的紧凑型射流可能不太可能。或者，我们不能排除由周向光电离区域自由吸收的同步加速器射流以及来自盘状电晕的自吸收非热同步加速器的假设，这些假设是高频多余成分的起源。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号