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We simulated the million degree interstellar medium and its soft X-ray imagesin the disk and halo of spiral galaxies using the bipolar hypershell (BHS)model. In this model hourglass-shaped expanding shells of several kpc radii areproduced by a sudden energy release in the central region. We then applied ourmodel to a mini-sample of starburst galaxies seen under different inclinationssuhc as the nearly edge-on galaxies NGC 253. Our results reproduce the X-raycharacteristics observed in the 0.1--2.4 keV ROSAT energy band: The bipolarhypershell morphology, the spectral energy distribution of the diffuse disk andhalo emission as well as absorption gaps in the diffuse X-ray emission causedby a shadowing of soft X-rays due to cold intervening gas in the disks of thegalaxies. The required total energy for the starburst is estimated to be of theorder of $10^{55}$ ergs, corresponding to the overall kinetic energy generatedin $\sim 10^4$ type-II supernova explosions. The expansion velocity of theshells is estimated to be $\sim 200$ \kms, which is necessary to heat the gasto $\sim 0.2$ keV (2.3 million K), and the age to be of the order of $3 \times10^7$ years. In the case of the very nearby galaxy NGC 253 all characteristicsof the BHS model can be studied with high spatial resolution. Using theproperty that the shell morphology is sensitive to the ambient densitydistribution, we propose using soft X-ray data to probe the gas distributionsin the disk, halo and intergalactic space. The application of our model toimages at higher spatial and spectral resolution, as provided by Chandra andXMM, will help us to further disentangle the ISM density distributions and willlead to a better understanding of the disk halo interface.Comment: To appear in Astron. Astrophys, Latex 9 pages, 6 figures in gi

Bipolar hypershell models of the extended hot interstellar medium in spiral galaxies