Face-on Dust Disks in Galaxies with Optical Jets
Face-on Dust Disks in Galaxies with Optical Jets
复制标题
星系中带有光学射流的面对面尘埃盘
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
A. Martel
中科院分区：
文献类型：
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作者：
W. Sparks;S. Baum;J. Biretta;F. Macchetto;F. Macchetto;A. Martel
射电星系中光学同步加速器喷流的存在相对罕见。在这里，我们展示了最近的五个显示光学射流的 FR I 3CR 射电星系，其中四个显示出几乎圆形的、可能是正面的尘埃盘的证据。这是对双重观点的有力支持，即（1）射流接近垂直于内部气盘出现，（2）仅当射流指向观察者时才能看到光学非热同步加速器发射。与视线的隐含临界角约为30°-40°；也就是说，如果射流与视线的角度小于约 40°，我们就会看到光学射流。相应的相对论 γ 因子约为 1.5，这与目前对喷气自行运动的观测结果一致，显示 M87 的范围可达 γ ~ 6。 γ ≈ 1.5 所暗示的相对较低的速度可能是由于统一理论中的射流整体减速或射流内的分层所致。未解析的原子核在光学中很常见。与从尘埃带推断的倾角相比，它们的光度也与光束概念一致。磁盘大小通常为数百秒差距到千秒差距。具有光学射流的星系 M87 不显示正面盘面，而是具有更复杂的径向尘埃和电离气体细丝。
The presence of optical synchrotron jets in radio galaxies is relatively rare. Here we show that of the nearest five FR I 3CR radio galaxies showing optical jets, four show evidence for almost circular, presumably face-on, dust disks. This is strong support for the twofold idea that (1) jets emerge close to perpendicular to inner gas disks and (2) optical nonthermal synchrotron emission is seen only when the jet points toward the observer. The implied critical angle to the line of sight is approximately 30°-40°; i.e., if the angle of the jet to the line of sight is less than about 40° we see an optical jet. The corresponding relativistic γ factor is ≈1.5, which is consistent with current observations of jet proper motion that show a range up to γ ~ 6 for M87. The relatively low speeds implied by γ ≈ 1.5 may be due to a global deceleration of the jet as in unified theories or else to stratification within the jet. Unresolved nuclei are common in the optical. Their luminosities are also consistent with the beaming concept when compared to inclination inferred from the dust lanes. The disk sizes are typically several hundred parsecs to kiloparsec size. The galaxy with an optical jet that does not show a face-on disk, M87, instead has more complex radial dust and ionized gas filaments.