MWA and VLA Observations of Diffuse Radio Lobes in M 87

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Main Authors: Wu, Linhui, Xie, Fu-Guo, Zheng, Qian, Guo, Quan, Shan, Huanyuan, Hu, Dan, Duchesne, Stefan W., Seymour, Nicholas, Wang, Jingying, Gu, Junhua, Wu, Qingwen, Zhu, Zhenghao, Johnston-Hollitt, Melanie, Riseley, Chris, Fan, Xu-Liang
Format: Preprint
Published: 2025
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author Wu, Linhui
Xie, Fu-Guo
Zheng, Qian
Guo, Quan
Shan, Huanyuan
Hu, Dan
Duchesne, Stefan W.
Seymour, Nicholas
Wang, Jingying
Gu, Junhua
Wu, Qingwen
Zhu, Zhenghao
Johnston-Hollitt, Melanie
Riseley, Chris
Fan, Xu-Liang
author_facet Wu, Linhui
Xie, Fu-Guo
Zheng, Qian
Guo, Quan
Shan, Huanyuan
Hu, Dan
Duchesne, Stefan W.
Seymour, Nicholas
Wang, Jingying
Gu, Junhua
Wu, Qingwen
Zhu, Zhenghao
Johnston-Hollitt, Melanie
Riseley, Chris
Fan, Xu-Liang
contents This study investigates the projected, quasi-symmetric $\sim\rm46\,kpc$-scale diffuse radio lobes surrounding the giant elliptical galaxy M\,87, utilizing well-sampled wideband ($\rm 60\,MHz-10.55\,GHz$) observations from MWA and VLA, supplemented by data from LOFAR and Effelsberg. The observed structures feature sharp edges and filaments, with nearly uniform and moderately steep spectral indices ($α$, mostly within $-1.2\leqα\leq-0.8$), indicating turbulence. Well-sampled radio spectra for the lobes' diffuse region are derived using the continuous injection (CI) model (with $α_{\rm inj}\simeq-0.86$ and $ν_{\rm b}\simeq1.72\rm\,GHz$), and for its three localized regions using the impulsive injection model (e.g., JP model). From energy equipartition analysis, we estimate the typical magnetic field strength in the lobes' diffuse region to be $B_{\rm eq}\simeq10\,μ\rm G$. The age of the lobes is estimated as $\sim30-50\,\rm~Myr$, based on lifetimes derived from the CI and JP models and sound crossing time. Outflow powers of $\sim(0.2-2)\times10^{44}\,\rm erg\,s^{-1}$ for the lobes' diffuse components and $\sim(1-11)\times10^{44}\,\rm erg\,s^{-1}$ for the whole source are calculated. With this power assessment, we conclude that the galactic stellar wind has a negligible effect, the active galactic nucleus (AGN)-driven jet can provide the necessary energy for the whole system. Furthermore, we argue that while the wind driven by current AGN activity is unlikely to power the lobes' diffuse components, an average enhancement of AGN activity by a factor of $\sim 10^2$ over the past $\sim 30-50$ Myr remains plausible.
format Preprint
id arxiv_https___arxiv_org_abs_2505_21929
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MWA and VLA Observations of Diffuse Radio Lobes in M 87
Wu, Linhui
Xie, Fu-Guo
Zheng, Qian
Guo, Quan
Shan, Huanyuan
Hu, Dan
Duchesne, Stefan W.
Seymour, Nicholas
Wang, Jingying
Gu, Junhua
Wu, Qingwen
Zhu, Zhenghao
Johnston-Hollitt, Melanie
Riseley, Chris
Fan, Xu-Liang
Astrophysics of Galaxies
This study investigates the projected, quasi-symmetric $\sim\rm46\,kpc$-scale diffuse radio lobes surrounding the giant elliptical galaxy M\,87, utilizing well-sampled wideband ($\rm 60\,MHz-10.55\,GHz$) observations from MWA and VLA, supplemented by data from LOFAR and Effelsberg. The observed structures feature sharp edges and filaments, with nearly uniform and moderately steep spectral indices ($α$, mostly within $-1.2\leqα\leq-0.8$), indicating turbulence. Well-sampled radio spectra for the lobes' diffuse region are derived using the continuous injection (CI) model (with $α_{\rm inj}\simeq-0.86$ and $ν_{\rm b}\simeq1.72\rm\,GHz$), and for its three localized regions using the impulsive injection model (e.g., JP model). From energy equipartition analysis, we estimate the typical magnetic field strength in the lobes' diffuse region to be $B_{\rm eq}\simeq10\,μ\rm G$. The age of the lobes is estimated as $\sim30-50\,\rm~Myr$, based on lifetimes derived from the CI and JP models and sound crossing time. Outflow powers of $\sim(0.2-2)\times10^{44}\,\rm erg\,s^{-1}$ for the lobes' diffuse components and $\sim(1-11)\times10^{44}\,\rm erg\,s^{-1}$ for the whole source are calculated. With this power assessment, we conclude that the galactic stellar wind has a negligible effect, the active galactic nucleus (AGN)-driven jet can provide the necessary energy for the whole system. Furthermore, we argue that while the wind driven by current AGN activity is unlikely to power the lobes' diffuse components, an average enhancement of AGN activity by a factor of $\sim 10^2$ over the past $\sim 30-50$ Myr remains plausible.
title MWA and VLA Observations of Diffuse Radio Lobes in M 87
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2505.21929