Signatures of feedback in the spectacular extended emission region of NGC 5972
Abstract
We present Chandra X-ray Observatory observations and Space Telescope Imaging Spectrograph spectra of NGC 5972, one of the 19 'Voorwerpjes' galaxies. This galaxy contains an extended emission-line region (EELR) and an arcsecond scale nuclear bubble. NGC 5972 is a faded active galactic nucleus (AGN), with EELR luminosity suggesting a 2.1 dex decrease in Lbol in the last ~5 × 104 yr. We investigate the role of AGN feedback in exciting the EELR and bubble given the long-term variability and potential accretion state changes. We detect broad-band (0.3-8 keV) X-ray emission in the near-nuclear regions, coincident with the [O III] bubble, as well as diffuse soft X-ray emission coincident with the EELR. The soft nuclear (0.5-1.5 keV) emission is spatially extended and the spectra are consistent with two APEC thermal populations (~0.80 and ~0.10 keV). We find a bubble age >2.2 Myr, suggesting formation before the current variability. We find evidence for efficient feedback with $P_{\textrm {kin}}/L_{\textrm {bol}}\sim 0.8~{{\ \rm per\ cent}}$, which may be overestimated given the recent Lbol variation. [O III] kinematics show a 300 km s-1 high-ionization velocity consistent with disturbed rotation or potentially the line-of-sight component of a ~780 km s-1 thermal X-ray outflow capable of driving strong shocks to photoionize the precursor material. We explore possibilities to explain the overall jet, radio lobe and EELR misalignment including evidence for a double supermassive black hole which could support a complex misaligned system.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2023
- DOI:
- 10.1093/mnras/stad2989
- arXiv:
- arXiv:2208.05915
- Bibcode:
- 2023MNRAS.526.4174H
- Keywords:
-
- galaxies: active;
- galaxies: individual: NGC5972;
- galaxies: ISM;
- galxies: Seyfert;
- X-rays: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 24 pages, 22 figures. Submitted to MNRAS