米波波段的 M87：LOFAR 观测图像
星系天体物理
2015-06-11 v1 宇宙学与河外天体物理
摘要
M87 是位于室女座星系团中心的一个巨椭圆星系，其中心拥有一个质量为 的超大质量黑洞，该黑洞的活动导致了环绕星系的延展（80 kpc）射电瓣的产生。物质落入中心黑洞所产生的能量通过相对论性喷流以及形态复杂的浮力气泡系统被喷射并转移至星系团内介质中，这些气泡向延展晕的边缘上升。在此，我们展示了利用新型低频阵列（LOFAR）对 M87 进行的首次观测，频率低至 20 MHz。我们在前所未有的高空间分辨率和动态范围下，获得了 M87 在低射电频段的图像。为了区分不同的同步辐射模型并限制源磁场、年龄和能量学特征，我们结合这些观测与存档数据，对 M87 延展射电晕进行了详细的光谱分析。我们未发现任何新延展辐射的迹象；相反，该源似乎受到星系团内介质高压的良好约束。连续注入相对论性电子的模型最能拟合我们的数据，并提供了一种情景，即喷流仍由活动星系核提供的新鲜相对论性粒子供给。我们认为，核心与晕区之间低频射电谱指数的差异意味着等离子体一旦离开核心区域便发生了强烈的绝热膨胀。延展晕的均分磁场强度约为 10 G，在粒子流更活跃的区域增加至约 13 G。基于同步辐射老化的连续注入模型给出的晕区年龄约为 40 Myr，进而推算出喷流动能功率为 erg/s。
引用
@article{arxiv.1210.1346,
title = {M87 at metre wavelengths: the LOFAR picture},
author = {F. de Gasperin and E. Orru' and M. Murgia and A. Merloni and H. Falcke and R. Beck and R. Beswick and L. Birzan and A. Bonafede and M. Bruggen and G. Brunetti and K. Chyzy and J. Conway and J. H. Croston and T. Ensslin and C. Ferrari and G. Heald and S. Heidenreich and N. Jackson and G. Macario and J. McKean and G. Miley and R. Morganti and A. Offringa and R. Pizzo and D. Rafferty and H. Roettgering and A. Shulevski and M. Steinmetz and C. Tasse and S. van der Tol and W. van Driel and R. J. van Weeren and J. E. van Zwieten and A. Alexov and J. Anderson and A. Asgekar and M. Avruch and M. Bell and M. R. Bell and M. Bentum and G. Bernardi and P. Best and F. Breitling and J. W. Broderick and A. Butcher and B. Ciardi and R. J. Dettmar and J. Eisloeffel and W. Frieswijk and H. Gankema and M. Garrett and M. Gerbers and J. M. Griessmeier and A. W. Gunst and T. E. Hassall and J. Hessels and M. Hoeft and A. Horneffer and A. Karastergiou and J. Koehler and Y. Koopman and G. Kuper and P. Maat and G. Mann and M. Mevius and D. D. Mulcahy and H. Munk and R. Nijboer and M. Kuniyoshi and J. Noordam and H. Paas and M. Pandey and V. N. Pandey and A. Polatidis and W. Reich and A. . P. Schoenmakers and J. Sluman and O. Smirnov and C. Sobey and B. Stappers and J. Swinbank and M. Tagger and Y. Tang and I. van Bemmel and W. van Cappellen and A. P. van Duin and M. van Haarlem and J. van Leeuwen and R. Vermeulen and C. Vocks and S. White and M. Wise and O. Wucknitz and P. Zarka},
journal= {arXiv preprint arXiv:1210.1346},
year = {2015}
}
备注
22 pages, 16 figures - Accepted in A&A