arXiv 1907.066482019-07astro-ph.GA

SOFIA/HAWC +跟踪NGC 1068中的磁场

SOFIA/HAWC+ traces the magnetic fields in NGC 1068

E. Lopez-Rodriguez, C. D. Dowell, T. J. Jones, D. A. Harper, M. Berthoud, D. Chuss, D. A. Dale, J. A. Guerra, R. T. Hamilton, L. W. Looney, J. M. Michail, R. Ni… 展开作者

E. Lopez-Rodriguez, C. D. Dowell, T. J. Jones, D. A. Harper, M. Berthoud, D. Chuss, D. A. Dale, J. A. Guerra, R. T. Hamilton, L. W. Looney, J. M. Michail, R. Nikutta, G. Novak, F. P. Santos, K. Sheth, J. Siah, J. Staguhn, I. W. Stephens, K. Tassis, C. Q. Trinh, D. Ward-Thompson, M. Werner, E. J. Wollack, E. Zweibel

备注：: 13 pages, 7 figures, Accepted for publication by ApJ
DOI：: 10.3847/1538-4357/ab5849

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摘要：

我们报告的第一个检测银河系的螺旋结构的热辐射磁排列尘埃颗粒的装置。我们的89 $μ$ m偏振成像的NGC 1068与高分辨率机载宽带相机/偏振计（HAWC+）在美国宇航局的平流层天文台红外天文学（SOFIA）也揭示了在附近的星系的内棒和活动星系核（AGN）的磁场结构。我们发现89 $μ$ m磁场矢量和其他示踪剂的螺旋臂之间的相关性，和一个对称的偏振模式作为一个函数的方位角所产生的投影和倾斜的磁盘场分量在天空的平面。观测结果可以用对数螺旋模型拟合，螺旋角为$16.9^{+2.7}_{-2.8}$ $^{\circ}$，圆盘倾角为$48\pm2^{\circ}$。我们推断，大部分的星际介质的偏振尘埃发射的起源是由一个磁场，紧跟着旋臂线程。内部的中央星爆盘（$<1.6$ kpc），偏振度被认为是低于远红外源在银河系中，并在最激烈的恒星形成的内部酒吧的外端附近的位置有最小值。在星暴环内部，磁场方向偏离了模型，沿着内棒的前缘变得更加径向。活动星系核的偏振通量和尘埃温度的峰值$\sim 3-6$“NE位于活动星系核流出物和周围星际介质之间的弓形激波处，但活动星系核本身的偏振度（$< 1$ %）在53和89 \um处都很弱。

英文摘要：

We report the first detection of galactic spiral structure by means of thermal emission from magnetically aligned dust grains. Our 89 $μ$m polarimetric imaging of NGC 1068 with the High-resolution Airborne Wideband Camera/Polarimeter (HAWC+) on NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) also sheds light on magnetic field structure in the vicinity of the galaxy's inner-bar and active galactic nucleus (AGN). We find correlations between the 89 $μ$m magnetic field vectors and other tracers of spiral arms, and a symmetric polarization pattern as a function of the azimuthal angle arising from the projection and inclination of the disk field component in the plane of the sky. The observations can be fit with a logarithmic spiral model with pitch angle of $16.9^{+2.7}_{-2.8}$$^{\circ}$ and a disk inclination of $48\pm2^{\circ}$. We infer that the bulk of the interstellar medium from which the polarized dust emission originates is threaded by a magnetic field that closely follows the spiral arms. Inside the central starburst disk ($<1.6$ kpc), the degree of polarization is found to be lower than for far-infrared sources in the Milky Way, and has minima at the locations of most intense star formation near the outer ends of the inner-bar. Inside the starburst ring, the field direction deviates from the model, becoming more radial along the leading edges of the inner-bar. The polarized flux and dust temperature peak $\sim 3-6$" NE of the AGN at the location of a bow shock between the AGN outflow and the surrounding interstellar medium, but the AGN itself is weakly polarized ($< 1$%) at both 53 and 89 \um.

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摘要：

英文摘要：

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