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SDSS-IV MaNGA: identification of active galactic nuclei in optical integral field unit surveys

Research output: Contribution to journalArticle

  • Dominika Wylezalek
  • Nadia L. Zakamska
  • Jenny E. Greene
  • Rogemar A. Riffel
  • Niv Drory
  • Brett H. Andrews
  • Andrea Merloni
  • Professor Daniel Thomas
In this paper, we investigate 2727 galaxies observed by MaNGA as of June 2016 to develop spatially resolved techniques for identifying signatures of active galactic nuclei (AGN). We identify 303 AGN candidates. The additional spatial dimension imposes challenges in identifying AGN due to contamination from diffuse ionized gas, extra-planar gas and photoionization by hot stars. We show that the combination of spatially-resolved line diagnostic diagrams and additional cuts on H$\alpha$ surface brighness and H$\alpha$ equivalent width can distinguish between AGN-like signatures and high-metallicity galaxies with LINER-like spectra. Low mass galaxies with high specific star formation rates are particularly difficult to diagnose and routinely show diagnostic line ratios outside of the standard star-formation locus. We develop a new diagnostic -- the distance from the standard diagnostic line in the line-ratios space -- to evaluate the significance of the deviation from the star-formation locus. We find 173 galaxies that would not have been selected as AGN candidates based on single-fibre spectral measurements but exhibit photoionization signatures suggestive of AGN activity in the MaNGA resolved observations, underscoring the power of large integral field unit (IFU) surveys. A complete census of these new AGN candidates is necessary to understand their nature and probe the complex co-evolution of supermassive black holes and their hosts.
Original languageEnglish
Pages (from-to)1499–1514
JournalMonthly Notices of the Royal Astronomical Society
Volume474
Issue number2
Early online date26 Oct 2017
DOIs
Publication statusPublished - Feb 2018

Documents

  • Identification of active galactic nuclei

    Rights statement: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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