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Magnetic support of the optical emission line filaments in NGC 1275


The giant elliptical galaxy NGC 1275, at the centre of the Perseus cluster, is surrounded by a well-known giant nebulosity of emission-line filaments1,2, which are plausibly in excess of 108 years old3. The filaments are dragged out from the centre of the galaxy by radio-emitting ‘bubbles’ rising buoyantly in the hot intracluster gas4, before later falling back. They act as markers of the feedback process by which energy is transferred from the central massive black hole to the surrounding gas. The mechanism by which the filaments are stabilized against tidal shear and dissipation into the surrounding extremely hot (4 × 107 K) gas has been unclear. Here we report observations that resolve thread-like structures in the filaments. Some threads extend over 6 kpc, yet are only 70 pc wide. We conclude that magnetic fields in the threads, in pressure balance with the surrounding gas, stabilize the filaments, so allowing a large mass of cold gas to accumulate and delay star formation.

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Figure 1: Image of the Hα emission from the core of the cluster.
Figure 2: Comparison of our HST image of the northern filament system (about 25 kpc north of the nucleus) with that from the WIYN telescope2.
Figure 3: Horseshoe filament system about 25 kpc to the northwest of the nucleus.
Figure 4: Clumps of stars and Hα filaments to the southeast and south of the nucleus.

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A.C.F. thanks the Royal Society for support. E.Z. acknowledges support from NSF AST 0507367 and J.S.G. from HST-GO-11207.07-A.

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Correspondence to A. C. Fabian.

Supplementary information

Supplementary Information

The file contains Supplementary Notes, Supplementary Figures and Legends 1-5, and Supplementary Table 1. The Supplementary Notes describe the Supplementary Figures. Supplementary Figure 1 shows the filament system in comparison with the galaxy, created by combining the ACS data for the three filters. Supplementary Figure 2 compares the Hα filaments with the distribution of blue light. Supplementary Figure 3 compares the filaments with the hard X-ray emission showing the weak shock around the core of the cluster. Supplementary Figure 4 shows the Hα emission in detail for three interesting regions. Supplementary Figure 5 compares the width of the Hα filaments with a stellar profile, showing that they are resolved. Supplementary Table 1 is a log of observations analysed in the paper. (PDF 2009 kb)

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Fabian, A., Johnstone, R., Sanders, J. et al. Magnetic support of the optical emission line filaments in NGC 1275. Nature 454, 968–970 (2008).

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