We present VLBA observations at 0.33 and 0.61 GHz, and VLA observations between 5 and 22 GHz, of subkiloparsec-scale radio emission from Mrk 231. In addition to jet components clearly associated with the active galzctic nucleus, we also find a smooth extended component of size 100-1000 pc most probably related to the purported massive star-forming disk in Mrk 231. The diffuse radio emission from the disk is found to have a steep spectrum at high frequencies, characteristic of optically thin synchrotron emission. The required relativistic particle density in the disk can be produced by a star formation rate of 220 M☉ yr-1 in the central kiloparsec. At low frequencies the disk is absorbed, most likely by ionized gas with an emission measure of 8 × 105 pc cm-6. We have also identified four candidate radio supernovae that, if confirmed, represent direct evidence for ongoing star formation in the central kiloparsec.
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机译：我们介绍了Mrk 231的亚千帕秒级无线电发射在0.33 GHz和0.61 GHz处的VLBA观测值以及5-22 GHz之间的VLA观测值。除了与活跃的银核明显相关的射流分量外，我们还发现了光滑的扩展分量100-1000 pc的大小最有可能与Mrk 231中所谓的大型恒星形成盘有关。发现该盘的漫射无线电发射在高频下具有陡峭的光谱，具有光学上薄的同步加速器发射特征。圆盘中所需的相对论粒子密度可以通过在中央千帕中的220 M rate yr-1的恒星形成速率来产生。在低频下，磁盘被吸收，最有可能被离子化气体吸收，其发射尺寸为8×105 pc cm-6。我们还确定了四个候选的放射性超新星，这些超新星如果被证实，则可以直接证明正在进行的恒星中部恒星形成。
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