{
  "id": "1406.5563",
  "version": "v1",
  "published": "2014-06-21T01:27:10.000Z",
  "updated": "2014-06-21T01:27:10.000Z",
  "title": "Theoretical Modeling of Emission-Line galaxies: New Classification Parameters for Mid-Infrared and Optical Spectroscopy",
  "authors": [
    "M. Meléndez",
    "T. M. Heckman",
    "M. Martínez-Paredes",
    "S. B. Kraemer",
    "C. Mendoza"
  ],
  "comment": "Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal. The paper contains 13 pages, 16 figures",
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We have carried out extensive and detailed photoionization modeling to successfully constrain the locations of different emission-line galaxies in optical and mid-infrared diagnostic diagrams. Our model grids cover a wide range in parameter space for the active galaxy continuum and starburst galaxies with different stellar population laws and metallicities. We compare the predicted AGN and star-formation mid-infrared line ratios [Ne III]15.56mm/[Ne II]12.81mm and [O IV]25.89mm/[Ne III]15.56mm to the observed values, and find that the best fit for the AGN is via a two-zone approximation. This two-zone approximation is a combination of a matter-bounded component, where [Ne III] and [O IV] are emitted efficiently, and a radiation-bounded component that maximizes [Ne II] emission. We overlay the predictions from this two-zone approximation onto the optical [O III]l5007/Hbeta and [N II]l6583/Halpha diagnostic diagram derived from the Sloan Digital Sky Survey, to find that the high-density and low-ionization radiation-bounded component in our two-zone AGN approximation model provides a good lower limit for [N II] emission. This establishes a new theoretical demarcation line for the minimum AGN contribution in this diagram. This new classification results by a factor of ~1.4 in a higher AGN population than predictions derived from previous divisions of star-forming galaxies. Similarly, we define a maximum AGN contribution in the [O III]/Hbeta and [N II]/Halpha diagram by using a two-zone approximation within a parameter range typical of the narrow-line region.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2014-06-21T01:27:10.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "emission-line galaxies",
      "classification parameters",
      "two-zone approximation",
      "optical spectroscopy",
      "theoretical modeling"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1093/mnras/stu1242",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2014,
      "month": "Sep",
      "volume": 443,
      "number": 2,
      "pages": 1358
    },
    "note": {
      "typesetting": "TeX",
      "pages": 13,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 1302341,
      "adsabs": "2014MNRAS.443.1358M"
    }
  }
}