The X-Ray Emission of NGC 5005: An Unobscured Low-luminosity Active Galactic Nucleus with a Weakly Accreting Broad-line Region

Abstract We present deep Chandra X-ray observations of NGC 5005, a LINER-dominated galaxy previously reported to host a broad H α emission line. The diffuse soft X-ray emission (<3 keV) extends out to ∼800 pc, while harder emission (>3 keV) is confined to the central ∼400 pc. Spatially resolved spectroscopy of the nuclear ( r < 150 pc) and extended (150 < r < 500 pc) regions reveals that these are best described by models including both photoionized and thermal plasma components, consistent with excitation by a low-luminosity active galactic nucleus (AGN) and shock-heated gas. Narrowband imaging and excitation maps from the Hubble Space Telescope (HST) support this interpretation, closely matching the X-ray morphology and ionization structure. The detection of a faint hard X-ray nuclear source with Chandra, combined with stringent upper limits from NuSTAR and Swift, and consistency with the X-ray luminosity predicted from the HST [O III ] λ 5007 emission, indicates that NGC 5005 hosts an intrinsically low-luminosity ( L bol ∼ 10 41 erg s −1 ), unobscured AGN. Despite the extremely low Eddington ratio inferred from our measurements ( λ Edd ∼ 5 × 10 −6 ), the presence of a broad H α line in the optical spectrum suggests the persistence of a thin accretion disk, challenging standard paradigms of accretion flow configurations at such low accretion rates.