Tightly Correlated X‐Ray/Hα–emitting Filaments in the Superbubble and Large‐Scale Superwind of NGC 3079

Using Chandra and HST we show that X-ray and H$\alpha$ filaments that formthe 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patternsat 0."8 resolution. This tight match seems to arise from cool disk gas that hasbeen driven by the wind, with X-rays being emitted from upstream, stand-offbowshocks or by conductive cooling at the cloud/wind interfaces. We find thatthe soft X-ray plasma has thermal and kinetic energies of$2\times10^{56}\sqrt{\eta_x}$ and $5\times10^{54}\sqrt{\eta_X}$ ergrespectively, where $\eta_X$ is the filling factor of the X-ray gas and may besmall; these are comparable to the energies of the optical line-emitting gas.X-rays are also seen from the base of the radio counterbubble that is obscuredoptically by the galaxy disk, and from the nucleus (whose spectrum shows the FeK$\alpha$ line). Hydrodynamical simulations reproduce the obbservations wellusing large filling factors within both filament systems; assuming otherwiseseriously underestimates the mass loss in the superwind. The superbubble issurrounded by a fainter conical halo of X-rays that fill the area delineated byhigh angle, H$\alpha$-emitting filaments, supporting our previous assertionthat these filaments form the contact discontinuity/shock between galaxy gasand shocked wind. About 40\arcsec (3 kpc) above the disk, an X-ray arc maypartially close beyond the bubble, but the north-east quadrant remains open,consistent with the superwind having broken out into at least the galaxy halo.Comment: 8 pages, 3 figures, to appear in Sept. 10 Ap