Clear detection of dusty torus signatures in a weak-line radio galaxy: the case of PKS 0043-42
Clear detection of dusty torus signatures in a weak-line radio galaxy: the case of PKS 0043-42
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清晰检测弱线射电星系中的尘埃环面特征：PKS 0043-42 的案例
DOI：
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
B. Mingo
中科院分区：
文献类型：
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作者：
C. R. Almeida;D. Dicken;C. Tadhunter;A. Ramos;K. Inskip;M. Hardcastle;B. Mingo
我们报告了到目前为止在一个弱线射电星系(WLRG)中发现的最清晰的尘埃环状信号。WLRG PKS0043-42(z=0.116)的深斯皮策红外光谱仪静止标架中红外光谱显示，在λ≳20μS有明显的光谱转换，暗示着暖尘埃，以及9.7μm硅酸盐的吸收特征。此外，基于钱德拉数据的硬X射线结果有力地支持了PKS 0043-42具有更典型的强线射电星系(SLRG)环面和吸积盘的图像。MIR谱和X射线谱在类似的红移下与其他WLRG的谱有明显的不同，这里我们表明前者可以成功地用块状环面模型拟合，参数为2型活动星系核环面：接近边(I=74°)，相对较宽(σ=60°)，外径为2pC，NH=1.6±0.20.1×1023厘米-2，活动星系核测辐射光度LAGNBOL=1.6±0.20.1×1044erg S-1。PKS 0043-42中一个致密环的存在提供了证据，证明这个WLRG是由冷而不是热的气体吸积提供燃料的。我们认为WLRG是一个多样化的群体，PKS0043-42可能代表了一种射电星系，其中AGN活动最近由于间歇性气体供应而被重新触发，或者窄线区(NLR)云的覆盖因子相对较低。
We report the clearest detection to date of dusty torus signatures in a weak-line radio galaxy (WLRG). The deep Spitzer InfraRed Spectrograph (IRS) rest-frame mid-infrared (MIR) spectrum of the WLRG PKS 0043-42 (z= 0.116) shows a clear spectral turnover at λ≳ 20 μs suggestive of warm dust, as well as a 9.7-μm silicate absorption feature. In addition, the hard X-ray results, based on Chandra data, strongly support a picture in which PKS 0043-42 has a torus and accretion disc more typical of strong-line radio galaxies (SLRGs). The MIR and X-ray spectra are markedly different from those of other WLRGs at similar redshifts, and here we show that the former can be successfully fitted with clumpy torus models with parameters characteristic of Type-2 AGN tori: close to edge-on (i= 74°) and relatively broad (σ= 60°), with an outer radius of 2 pc, NH= 1.6 ±0.20.1 × 1023 cm-2, and AGN bolometric luminosity LAGNbol= 1.6 ±0.20.1 × 1044 erg s-1. The presence of a compact torus in PKS 0043-42 provides evidence that this WLRG is fuelled by cold, rather than hot, gas accretion. We suggest that WLRGs are a diverse population, and PKS 0043-42 may represent a type of radio galaxy in which the AGN activity has been recently re-triggered as a consequence of intermittent gas supply, or in which the covering factor of the narrow-line region (NLR) clouds is relatively low.
DOI：
10.1088/0004-637x/722/2/1333
发表时间：
2010
期刊：
The Astrophysical Journal
影响因子：
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作者：
Dicken D
通讯作者：
Dicken D