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Signatures of Feedback in the Spectacular Extended Emission Region of NGC 5972

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Thomas Harvey
  • W Peter Maksym
  • William Keel
  • Michael Koss
  • Vardha N Bennert
  • S D Chojnowski
  • Ezequiel Treister
  • Carolina Finlez
  • Chris J Lintott
  • Alexei Moiseev
  • Brooke D Simmons
  • Lia F Sartori
  • Megan Urry
<mark>Journal publication date</mark>31/12/2023
<mark>Journal</mark>Monthly Notices of the Royal Astronomical Society
Issue number3
Number of pages18
Pages (from-to)4174-4191
Publication StatusPublished
Early online date17/10/23
<mark>Original language</mark>English


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 &gt;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.