gamma-ray双星LS 5039的变化毫角秒射电形态
The changing milliarcsecond radio morphology of the gamma-ray binary LS 5039
摘要：
上下文LS 5039是迄今为止发现的少数几个TeV发射X射线的双星之一。其多波长发射的动力源可以是微类星体场景中的吸积或年轻非吸积脉冲星场景中的风相互作用。目标。提供新的高分辨率无线电图像，并将其与不同情景下的预期行为进行比较。方法.我们分析甚长基线阵列（VLBA）的射电观测，提供形态和天体测量信息在毫角秒尺度。结果我们检测到相隔五天获得的两个图像之间的形态变化。在两个运行中，存在具有恒定通量密度的核心组件，以及具有在两个运行之间改变12 +/-3度的位置角（PA）的细长发射。源在第一次运行中几乎是对称的，而在第二次运行中是不对称的。天体测量的结果不是决定性的。结论.一个简单和无冲击的微类星体场景无法轻易解释观测到的形态变化。年轻的非吸积脉冲星的解释需要双星系统的倾角非常接近没有X射线食的上限。
英文摘要：
Context. LS 5039 is one of the few TeV emitting X-ray binaries detected so far. The powering source of its multiwavelength emission can be accretion in a microquasar scenario or wind interaction in a young nonaccreting pulsar scenario. Aims. To present new high-resolution radio images and compare them with the expected behavior in the different scenarios. Methods. We analyze Very Long Baseline Array (VLBA) radio observations that provide morphological and astrometric information at milliarcsecond scales. Results. We detect a changing morphology between two images obtained five days apart. In both runs there is a core component with a constant flux density, and an elongated emission with a position angle (PA) that changes by 12+/-3 degrees between both runs. The source is nearly symmetric in the first run and asymmetric in the second one. The astrometric results are not conclusive. Conclusions. A simple and shockless microquasar scenario cannot easily explain the observed changes in morphology. An interpretation within the young nonaccreting pulsar scenario requires the inclination of the binary system to be very close to the upper limit imposed by the absence of X-ray eclipses.
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