arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1105.3473astro-ph.HEastro-ph.CO
收藏

巨射电星系DA 240东叶电子和磁能密度的朱雀测量

Suzaku measurement of electron and magnetic energy densities in the east lobe of the giant radio galaxy DA 240

Naoki Isobe, Hiromi Seta, Makoto S. Tashiro

摘要:

对巨型射电星系DA 240(其大小为1.48 Mpc)的朱雀数据进行仔细分析,发现与其东叶有关的弥散X射线发射。漫射X射线光谱用简单的幂律模型描述,光子指数为1.92(-0.17+0.13)(-0.06+0.04),其中第一和第二误差代表统计误差和系统误差。与同步加速器射电光子指数(326 - 608.5 MHz,1.95 ± 0.01)的一致性确保了过量的X射线发射归因于同步辐射电子的逆康普顿发射,从而增强了宇宙微波背景光子。从X射线通量密度来看,51.5 ± 3.9与326 MHz时同步辐射强度10.30 ± 0.12 Jy相比,磁和电子的能量密度估计为(3.0 +-0.2 +-0.4)\times 10^(-14)ergs/cm 3和u_e =(3.4(-0.2+0.3)(-0.4+0.5))\times 10^(-14)ergs/cm 3,电子洛伦兹因子为10^3 - 10^5。因此,东瓣处于电子与磁场的均分状态,参数为u_e/u_m = 1.1(-0.1+0.2)(-0.2+0.4)。DA 240的东叶是射电星系X射线探测到的所有叶中u_e值最低的。将大小约为1 Mpc的巨型射电星系的能量与较小天体的能量进行比较,表明射电星系在从100 kpc演化到1 Mpc时可能会失去喷流能量。

英文摘要:

A careful analysis of the Suzaku data of the giant radio galaxy DA 240, of which the size is 1.48 Mpc, revealed diffuse X-ray emission associated with its east lobe. The diffuse X-ray spectrum was described with a simple power-law model with a photon index of 1.92 (-0.17+0.13) (-0.06+0.04), where the first and second errors represent the statistical and systematic ones. The agreement with the synchrotron radio photon index, 1.95 +- 0.01 in 326 -- 608.5 MHz, ensures that the excess X-ray emission is attributed to the inverse Compton emission from the synchrotron-radiating electrons, boosting up the cosmic microwave background photons. From the X-ray flux density, 51.5 +-3.9 (-5.4+6.2) nJy at 1 keV derived with the photon index fixed at the radio index, in comparison with the synchrotron radio intensity of 10.30 +- 0.12 Jy at 326 MHz, the magnetic and electron energy densities was estimated as u_m = (3.0 +-0.2 +-0.4) \times 10^(-14) ergs/cm3 and u_e = (3.4 (-0.2+0.3) (-0.4+0.5)) \times 10^(-14) ergs/cm3 integrated over the electron Lorentz factor of 10^3 -- 10^5, respectively. Thus, the east lobe is found to reside in an equipartition condition between the electrons and magnetic field parametrized as u_e/u_m = 1.1 (-0.1+0.2) (-0.2+0.4). The east lobe of DA 240 is indicated to exhibit the lowest value of u_e, among all the X-ray detected lobes of radio galaxies. A comparison of the energetics in the giant radio galaxies with a size of about 1 Mpc to those in the smaller objects suggests a possibility that radio galaxies lose their jet power, as they evolve from 100 kpc to 1 Mpc.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑