ROSAT EVIDENCE FOR AGN AND SUPERWIND ACTIVITY IN NGC-6240 AND NGC-2782

We present ROSAT observations of the starburst galaxy NGC 2782 (HRI pl us a weak PSPC frame) and the ultraluminous infrared galaxy NGC 6240 ( PSPC). The (0.1-2.4) keV spectra of both objects appear similar. Howev er, due to better sampling spectral modeling is only warranted in case of NGC 6240 for which both a single thermal Raymond-Smith model (kT = 0.44 +/- 0.15 keV) or a hybrid model consisting of 80% power-law with the canonical photon index -1.9 plus 20% Raymond-Smith contribution ( kT = 0.63 +/- 0.35 keV) lead to good fits. However, the single thermal model turns out to be unlikely because it yields a luminosity of 3.8 10(43) erg s(-1), which is hard to reach in a starburst superwind-scen ario. The hybrid model leads to a more moderate luminosity of 5.2 10(4 2) erg s(-1), of which 1.010(42) erg s(-1) can be attributed to shocke d super wind gas. We link the remaining 4.2 10(42) erg s(-1) powerlaw to an AGN component because the alternative of inverse-compton scatter ing of the FIR radiation leads to a too low flux when estimated with a vailable data. The result appears to be consistent with preliminarily announced ASCA observations. For NGC 2782 we find L-x(0.1-2.4 keV) = 4 10(41) erg s(-1) (within a factor of four) which can be explained by emission from a shocked superwind region with a high preshock density in agreement with earlier optical evidence for an outflowing supershel l.