The Chandra High Energy Transmission Grating Observation of an X - ray Ionization Cone in Markarian 3

We present a preliminary analysis of the first high-resolution X-ray spectrum of a Seyfert 2 galaxy, Mkn 3, obtained with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The high-energy spectrum (λ . 4 Å) is dominated by reflection of the AGN continuum radiation in a cold optically thick medium and contains bright Kα fluorescent lines from iron and silicon, as well as weak, blended lines from sulfur and magnesium. The soft X-ray emission (4 . λ . 23 Å) is spatially extended along the O [III] ionization cone and shows discrete signatures of emission following recombination and photoexcitation produced in a warm photoionized region. The measured iron L line fluxes indicate that emission from collisionally ionized plasma is almost completely negligible, and does not contribute significantly to the total energy budget of the X-ray emission. We find that significant fractions of the Hand He-like resonance lines, as well as the observed iron L lines are produced through re-emission from the warm absorbing medium observed in Seyfert 1 galaxies. Its X-ray spectral properties are qualitatively consistent with those of a typical Seyfert 1 galaxy viewed at a different orientation, and provide further convincing evidence for the existence of an obscured Seyfert 1 nucleus in Mkn 3. Subject headings: galaxies: individual (Mkn 3) — galaxies: active — galaxies: nuclei — galaxies: Seyfert — techiniques: spectroscopic — X-rays: galaxies