A tale of two narrow-line regions: Ionization, kinematics, and spectral energy distributions for a local pair of merging obscured active galaxies

Kevin N. Hainline, Ryan C. Hickox, Chien Ting Chen, Christopher M. Carroll, MacKenzie L. Jones, Alexandros S. Zervos, Andrew D. Goulding

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

We explore the gas ionization and kinematics, as well as the optical-IR spectral energy distributions for UGC 11185, a nearby pair of merging galaxies hosting obscured active galactic nuclei (AGNs), also known as SDSS J181611.72+423941.6 and J181609.37+423923.0 (J1816NE and J1816SW, z ≈ 0.04). Due to the wide separation between these interacting galaxies (∼23 kpc), observations of these objects provide a rare glimpse of the concurrent growth of supermassive black holes at an early merger stage. We use BPT line diagnostics to show that the full extent of the narrow-line emission in both galaxies is photoionized by an AGN, and confirm the existence of a 10 kpc-scale ionization cone in J1816NE, while in J1816SW the AGN narrow-line region is much more compact (1-2 kpc) and relatively undisturbed. Our observations also reveal the presence of ionized gas that nearly spans the entire distance between the galaxies, which is likely in a merger-induced tidal stream. In addition, we carry out a spectral analysis of the X-ray emission using data from XMM-Newton. These galaxies represent a useful pair to explore how the [O iii] luminosity of an AGN is dependent on the size of the region used to explore the extended emission. Given the growing evidence for AGN "flickering" over short timescales, we speculate that the appearances and impacts of these AGNs may change multiple times over the course of the galaxy merger, which is especially important given that these objects are likely the progenitors of the types of systems commonly classified as "dual AGNs."

Original languageEnglish (US)
Article number42
JournalAstrophysical Journal
Volume823
Issue number1
DOIs
StatePublished - May 20 2016
Externally publishedYes

Keywords

  • galaxies: active
  • galaxies: evolution
  • galaxies: interactions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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