斯蒂芬五重星系的射电连续辐射观测：激波的年龄、动力学与起源

本文利用多波段射电观测数据，对斯蒂芬五重星系（HCG 92）的射电连续辐射特性进行了详细研究。研究重点分析了该星系群中的射电脊及其弥散辐射，揭示了其物理机制主要源于星系碰撞产生的强激波，并估算了激波的演化年龄。

arXiv:2608.26461v1 Announce Type: new Abstract: We present a detailed, multi-band radio continuum study of the compact galaxy group Stephan's Quintet (HCG 92). We use a combination of new (MeerKAT, uGMRT) and archival (LOFAR, VLA) observations covering the $\rm 120\,MHz{-}8\,GHz$ frequency range to examine the radio properties of the group, focusing on the famous radio ridge and surrounding diffuse emission. We find filamentary substructure and branching in the southern half of the ridge, confirm an extension of the ridge to the northwest, and identify for the first time a radio counterpart to the gas bridge linking the ridge and NGC 7319. The northern ridge, northwest extension and diffuse emission have relatively steep, curved spectra, with a high-frequency spectral index gradient running north-south along the ridge. We show that the ridge emission primarily arises from a single physical mechanism, probably strong ($\mathcal{M}\simeq 40-100$) shocks in cold gas, caused by the $\rm \sim850-1000\,kms^{-1}$ collision between NGC 7318B and tidal gas filaments produced by past galaxy interactions. Synchrotron spectral age estimates suggest the collision began at the north end of the ridge $\rm \sim20\,Myr$ ago, and finished only $\rm \sim5-6\,Myr$ ago in the south, with the southern end of the shocked ridge likely still