The upgraded Giant Metrewave Radio Telescope (GMRT) has been used to image the head-tail radio galaxy NGC 4869 in the Coma cluster with an angular resolution of 6.26 arcsec at 250-500 MHz and 2.18 arcsec at the 1050-1450 MHz bands. The archival legacy GMRT data have also been used to image the source with angular resolutions from 4.9 to 21.8 arcsec at 610 MHz, 325 MHz, 240 MHz, and 150 MHz. We find that the ~200 kpc scale radio morphology consists of five distinct regions with the clear presence of a pinch at ~1.4 arcmin (= 38.8 kpc) and a ridge at ~3.4 arcmin (= 94.2 kpc) from the head. The sharp bend by ~70 deg at ~3.5 arcmin (= 97 kpc) from the head is possibly due to projection effects. The radio spectra show progressive spectral steepening as a function of distance from the head and there is possibly re-acceleration of the synchrotron electrons and perhaps also magnetic field re-generation in the 6-208 arcsec (= 2.8-96.1 kpc) region of the jet. We report a steep spectrum sheath layer enveloping a flat spectrum spine, hinting at a transverse velocity structure with a fast-moving spine surrounded by a slow-moving sheath layer. We also derive the lifetimes of the radiating electrons and equipartition parameters. A plausible explanation for the characteristic feature, a ridge of emission perpendicular to the direction of tail is the flaring of a straight, collimated radio jet as it crosses a surface brightness edge due to Kelvin-Helmholtz instabilities.

中文翻译：

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彗发星团中的 NGC 4869：扭曲、包裹、重叠和弯曲

升级后的巨型米波射电望远镜 (GMRT) 已被用于对后发星团中头尾射电星系 NGC 4869 进行成像，其角分辨率在 250-500 MHz 下为 6.26 角秒，在 1050-1450 MHz 频带下为 2.18 角秒。存档的传统 GMRT 数据也已用于在 610 MHz、325 MHz、240 MHz 和 150 MHz 下以 4.9 到 21.8 弧秒的角分辨率对源进行成像。我们发现~200 kpc 尺度的无线电形态由五个不同的区域组成，在~1.4 arcmin (= 38.8 kpc) 处有一个夹点，在头部~3.4 arcmin (= 94.2 kpc) 处有一个脊。从头部在 ~3.5 arcmin (= 97 kpc) 处急剧弯曲 ~70 度可能是由于投影效应。射电频谱显示出作为与头部距离的函数的渐进式频谱陡峭，并且同步加速器电子可能会重新加速，并且可能在 6-208 弧秒（= 2.8-96.1 kpc）区域中还存在磁场再生。喷射。我们报告了一个陡峭的频谱鞘层包裹着一个平坦的频谱脊柱，暗示了一个横向速度结构，一个快速移动的脊柱被一个缓慢移动的鞘层包围。我们还推导出辐射电子的寿命和均分参数。对于特征性特征的合理解释，垂直于尾部方向的发射脊是由于开尔文 - 亥姆霍兹不稳定性而穿过表面亮度边缘时直的准直射流的燃烧。1 kpc) 喷射区域。我们报告了一个陡峭的频谱鞘层包裹着一个平坦的频谱脊柱，暗示了一个横向速度结构，一个快速移动的脊柱被一个缓慢移动的鞘层包围。我们还推导出辐射电子的寿命和均分参数。对于特征性特征的合理解释，垂直于尾部方向的发射脊是由于开尔文 - 亥姆霍兹不稳定性而穿过表面亮度边缘时直的准直射流的燃烧。1 kpc) 喷射区域。我们报告了一个陡峭的频谱鞘层包裹着一个平坦的频谱脊柱，暗示了一个横向速度结构，一个快速移动的脊柱被一个缓慢移动的鞘层包围。我们还推导出辐射电子的寿命和均分参数。对于特征性特征的合理解释，垂直于尾部方向的发射脊是由于开尔文 - 亥姆霍兹不稳定性而穿过表面亮度边缘时直的准直射流的燃烧。