Deep Chandra Observations of NGC 5728. III. Probing the High-resolution X-Ray Morphology and Multiphase Interstellar Medium Interactions in the Circumnuclear Region

Abstract

We present a detailed imaging analysis of 260 ks of subarcsecond resolution Chandra (ACIS-S) observations of the nearby Seyfert 2 galaxy NGC 5728. Our study focuses on the bright and diffuse soft X-ray emission within the galaxy's inner ∼1 kpc. By comparing the X-ray emission across different energy bands, we identify localized variations in the absorbing column and emission processes. We observe more X-ray absorption in the direction perpendicular to the bicone, which is co-located with an inner warped CO disk in the galaxy. The innermost region, which shows the strongest excess of hard X-ray emission, is spatially coincident with the CO (2–1) emission from the Atacama Large Millimeter/submillimeter Array and dusty spirals we find in a Hubble Space Telescope V − H color map. We detect soft extended emission associated with the circumnuclear star-forming ring at ∼1 kpc, suggestive of hot gas with kT = 0.44 keV. We derive measurements for the hot gas mass, M = 7.9 × 10 ^5 M _⊙ , pressure, p = 2.0 × 10 ^−10 dyne cm ^−2 , and cooling times, τ _c = 193.2 Myr. In the vicinity of the star-forming ring, we detect two X-ray point sources, with soft X-ray spectra, and 0.3–7 keV luminosities L ∼ 8 × 10 ^38 erg s ^−1 . These properties suggest X-ray binaries.

Keywords

• Seyfert galaxies
• AGN host galaxies