A More Efficient Search for H2O Megamaser Galaxies: The Power of X-Ray and Mid-infrared Photometry

C. Y. Kuo, J. Y. Hsiang, H. H. Chung, A. Constantin, Y. Y. Chang, E. Da Cunha, D. Pesce, W. T. Chien, B. Y. Chen, J. A. Braatz, Ingyin Zaw, S. Matsushita, J. C. Lin

Research output: Contribution to journalArticlepeer-review


We present an investigation of the dependence of H2O maser detection rates and properties on the mid-IR active galactic nucleus (AGN) luminosity, L AGN, and the obscuring column density, N H, based on mid-IR and hard X-ray photometry. Based on spectral energy distribution fitting that allows for decomposition of the black hole accretion and star formation components in the mid-infrared, we show that the megamaser (disk maser) detection rate increases sharply for galaxies with 12 μm AGN luminosity greater than 1042 erg s-1, from 3% (2%) to 12% (5%). By using the ratio of the observed X-ray to mid-IR AGN luminosity as an indicator of N H, we also find that megamaser (disk maser) detection rates are boosted to 15% (7%) and 20% (9%) for galaxies with N H ≥ 1023 cm-2 and N H ≥ 1024 cm-2, respectively. Combining these column density cuts with a constraint for high (≥1042 erg s-1) predicts further increases in the megamaser (disk maser) detection rates to 19% (8%) and 27% (14%), revealing unprecedented potential increases of the megamaser and disk maser detection rates by a factor of 7-15 relative to the current rates, depending on the chosen sample selection criteria. A noteworthy aspect of these new predictions is that the completeness rates are only compromised mildly, with the rates remaining at the level of 95%(50%) for sources with N H ≥ 1023 cm-2 (N H ≥ 1024 cm-2). Applying these selection methods to current X-ray AGN surveys predicts the detection of 15 new megamaser disks.

Original languageEnglish (US)
Article number18
JournalAstrophysical Journal
Issue number1
StatePublished - Mar 20 2020

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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