Rejuvenated radio galaxies J0041+3224 and J1835+6204: how long can the quiescent phase of nuclear activity last?
Rejuvenated radio galaxies J0041+3224 and J1835+6204: how long can the quiescent phase of nuclear activity last?
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恢复活力的射电星系 J0041 3224 和 J1835 6204：核活动的静止阶段能持续多久？
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Nandi
中科院分区：
文献类型：
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作者：
C. Konar;M. Hardcastle;M. Jamrozy;J. Croston;S. Nandi
我们展示了两个著名的双双射电星系J0041+3224和J1835+6204的射电观测，频率范围从150到8460 MHz，使用巨型米波射电望远镜和甚大阵列。这些观测，在一个大的无线电频率范围内，使我们能够确定内部和外部叶的光谱。我们对其内外叶的详细光谱老化分析表明，双双射电星系的外部双子星是由前一个活动周期产生的，而内部双子星是由当前的活动周期产生的。两个源的内双频的（核心减去的）频谱在很大的频率范围内是幂律。我们发现J0041+3224的静止阶段的持续时间是之前活动的活跃阶段的4%到28%之间。J1835+6204的外西北叶有一个紧凑的热点，两个外热点的区域都有接近幂定律（而不是弯曲）的光谱，这表明在中央发动机停止为射流提供动力之前，前一集喷射出的射流物质仍然在为外叶提供能量。我们估计J1835+6204的静止阶段的持续时间小于前一次活动的活跃阶段持续时间的5%。因此，我们得出结论，在这种类型的射电星系中，静止阶段的持续时间可能短至活动阶段的百分之几。
We present radio observations of two well-known double-double radio galaxies, J0041+3224 and J1835+6204, at frequencies ranging from 150 to 8460 MHz, using both the Giant Metrewave Radio Telescope and the Very Large Array. These observations, over a large radio frequency range, enable us to determine the spectra of the inner and outer lobes. Our detailed spectral ageing analysis of their inner and outer lobes demonstrates that the outer doubles of double-double radio galaxies are created by the previous cycle of activity, while the inner doubles are due to the present cycle of activity. The (core subtracted) spectra of the inner doubles of both sources are power laws over a large frequency range. We found that the duration of the quiescent phase of J0041+3224 is between 4 and 28 per cent of the active phase of the previous activity. The outer north-western lobe of J1835+6204 has a compact hotspot and the regions of both the outer hotspots have close to power-law (rather than curved) spectra, which indicates that the outer lobes are still fed by jet material ejected in the previous episode just before the central engine stopped powering the jet. We estimate that the duration of the quiescent phase of J1835+6204 is < 5 per cent of the duration of the active phase of the previous activity. Therefore, we conclude that the duration of the quiescent phase can be as short as a few per cent of the active phase in radio galaxies of this type.
DOI：
10.1111/j.1365-2966.2008.13162.x
发表时间：
2008-02
影响因子：
4.8
作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing
通讯作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing