4/15/2023 0 Comments Ram pressure stripping massOur favored model is that SN feedback in the disks of star-forming galaxies create, via blow-out and venting of hot gas from the disk, tenuous exponential atmospheres of density scale height Hg ~ 4-8 kpc. This is consistent with the origin of the X-ray emitting gas being either metal-enriched merged SN ejecta or shock-heated ambient halo or disk material with moderate levels of metal depletion onto dust. ![]() The Chandra ACIS X-ray spectra of extraplanar emission from all these galaxies can be fitted with a common two-temperature spectral model with an enhanced α-to-iron element ratio. Active galactic nuclei, where present, appear to play no role in powering or shaping the outflows from the starburst galaxies in this sample. No X-ray emission was detected from the halos of the two low-mass normal spiral galaxies NGC 6503 and NGC 4244. ![]() The presence of extraplanar X-ray emission is always associated with the presence of extraplanar optical line emission of similar vertical extent. In general, the vertical distribution of the halo-region X-ray surface brightness is best described as an exponential, with the observed scale heights of the sample galaxies lying in the range Heff ~ 2-4 kpc. Of the eight galaxies in which diffuse X-ray emitting halos are found (the starbursts and the normal spiral NGC 891), significant spatial variation in the spectral properties of the extraplanar emission (|z| ≥ 2 kpc) is only found in two cases: NGC 3628 and NGC 4631. We provide a variety of quantitative measures of how the spectral hardness and surface brightness of the diffuse X-ray emission varies with increasing height z above the plane of each galaxy. The most spectacular cases of this are found in NGC 1482 (for which we provide the first published X-ray observation) and NGC 3079. In general, the morphology of the extraplanar diffuse X-ray emission is very similar to the extraplanar Hα filaments and arcs, on both small and large scales (scales of tens of parsecs and kiloparsecs, respectively). We have combined the X-ray observations with existing, comparable-resolution, ground-based Hα and R-band imaging and present a mini-atlas of images on a common spatial and surface brightness scale to aid cross-comparison. ![]() The X-ray observations make use of the unprecedented spatial resolution of the Chandra X-ray observatory to more robustly than before remove X-ray emission from point sources and hence obtain the X-ray properties of the diffuse thermal emission alone. Abstract: We present arcsecond resolution Chandra X-ray and ground-based optical Hα imaging of a sample of 10 edge-on star-forming disk galaxies (seven starburst and three "normal" spiral galaxies), a sample that covers the full range of star formation intensity found in disk galaxies.
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