Radio halos require the coexistence of extra-planar cosmic rays and magnetic fields. Because cosmic rays are injected and accelerated by processes related to star formation in the disk, they have to be transported from the disk into the halo. A vertical large-scale magnetic field can significantly enhance this transport. We observed NGC 253 using radio continuum polarimetry with the Effelsberg and VLA telescopes. The radio halo of NGC 253 has a dumbbell shape with the smallest vertical extension near the center. With an estimate for the electron lifetime, we measured the cosmic-ray bulk speed as 300+/-30 km/s which is constant over the extent of the disk. This shows the presence of a "disk wind" in NGC 253. We propose that the large-scale magnetic field is the superposition of a disk (r,phi) and a halo (r,z) component. The disk field is an inward-pointing spiral with even parity. The conical (even) halo field appears in projection as an X-shaped structure, as observed in other edge-on galaxies. Interaction by compression in the walls of the superbubbles may explain the observed alignment between the halo field and the lobes of hot Halpha- and soft X-ray emitting gas. The disk wind is a good candidate for the transport of small-scale helical fields, required for efficient dynamo action, and as a source for the neutral hydrogen observed in the halo.
The stellar populations of the AGN/Starburst galaxy NGC7582
NGC 7582被定义为星暴/活动星系核星系，因为它的光学和X射线光谱显示了这两种特征。在这项工作中，我们展示了一个恒星星族建模与双子座南望远镜的数据立方体的结果。我们发现，视场中$\sim$ 90%的光是由年龄不到10亿年的恒星发出的。一次强烈的爆发发生在大约$\sim$ 600万年前，其金属丰度接近太阳。我们还发现了一个沃尔夫-拉叶星系团。
The AGN properties of the starburst galaxy NGC 7582
NGC 7582在光学\cite [（Veron et al. 1981）]中被确定为一个星爆星系{Veron et al.（1981）}但它的X射线辐射是典型的塞弗特1星系\cite [（Ward et al. 1978）]{Ward et al.（1978）}。我们分析了Gemini-South望远镜上GMOS-IFU获得的这个物体的数据立方体。在使用{ \sc starlight}代码\cite [（Cid Fernandes et al.（2005）]{Cid Fernandes et al.（2005）}减去恒星成分后，我们寻找活动星系核的光学特征。我们在来源中检测到广泛的$Hα$组分（图\ref{fig1}），其中\cite [Bianchi et al.（2007）]{Bianchi et al.（2007）}在HST光学图像中识别出活动星系核。我们还发现了一个广泛的$Hβ$特征（图\ref{fig2}），但它的发射揭示了一个扩展的源。我们认为这是活动星系核的光在电离锥中散射的结果。我们认为NGC 7582是一个塞弗特1星系。还确定了一些其他“热点”和沃尔夫-拉叶特特征。
We explore the role that gravitational instability plays in NGC 1068, a nearby Seyfert galaxy that exhibits unusually vigorous starburst activity. For this purpose, we use the Romeo-Falstad disc instability diagnostics and data from BIMA SONG, SDSS and SAURON. Our analysis illustrates that NGC 1068 is a gravitationally unstable "monster". Its starburst disc is subject to unusually powerful instabilities. Several processes, including AGN/stellar feedback, try to quench such instabilities from inside out by depressing the surface density of molecular gas across the central kpc, but they do not s…
We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies within 50 Mpc: NGC 3256 and NGC 3310. Both galaxies are detected by both Chandra and NuSTAR, which together provide the first-ever spectra of these two galaxies spanning 0.3-30 keV. The X-ray emission from both galaxies is spatially resolved by Chandra; we find that hot gas dominates the E < 1-3 keV emission while ultraluminous X-ray sources (ULXs) dominate at E > 1-3 keV. The NuSTAR galaxy-wide spectra of both galaxies follow steep power-law distributions with Gamma ~ 2.6 at E > 5-7 keV, simil…
