耀变体射电喷流的相对论性束流性质

Relativistic Beaming Properties of Radio Jets in Blazars

利用MOJAVE数据库15 GHz的总流量密度变化的监测数据,分析了一个大样本耀变体射电喷流的相对论性束流性质,计算了源的亮温度、多普勒增亮因子、洛伦兹因子、视向角与光变指数等。研究发现,该样本中多数耀变体是多普勒增强的,且平谱射电类星体整体上比蝎虎天体具有更强的多普勒增亮效应。洛伦兹因子与光变指数的计算表明,与平谱射电类星体相比,蝎虎天体有较小的洛伦兹因子和光变指数。通过视向角的计算分析发现,89%的耀变体的视向角小于21°。此外,还分析了耀变体的亮温度与光变指数的关系,发现它们具有较显著的相关性。

We have calculated the variability brightness temperatures by analyzing the light curves for a large sample of blazar using total flux density monitoring data at 15 GHz from the MOJAVE database, and determined the Doppler boosting factors by assuming the sameintrinsic brightness temperature for each source. We have calculated the Lorentz factorsand viewing angles of 123 blazars, which include 99 flat spectrum radio quasars and 24 BLLacertae objects, using new apparent jet speed data. We have divided the flat spectrum radioquasars and the BL Lacertae objects into different subclasses, and analyzed the variabilitybrightness temperature, the Doppler boosting factor, the Lorentz factor, viewing angle andvariability index of each subclass. We find that most of blazars in our sample are Dopplerboostedand Doppler boosting factors of flat spectrum radio quasars are higher than those ofBL Lacertae objects, and the high-polarization flat spectrum radio quasars have the greatestDoppler boosting, while the low-polarization flat spectrum radio quasars and low-spectralpeaked BL Lacertae objects are less boosted. The Lorentz factor and variability indexes ofBL Lacertae objects are smaller than those of flat spectrum radio quasars。It is also foundthat 89% of the sources have a small viewing angle of less than 21 degrees. We also analyzedthe relationship between the brightness temperature and the variability index, and find thatthey have a significant correlation.