{
  "id": "2112.01550",
  "version": "v2",
  "published": "2021-12-02T19:00:06.000Z",
  "updated": "2022-04-13T20:43:28.000Z",
  "title": "The effect of spiral arms on the Sérsic photometry of galaxies",
  "authors": [
    "Alessandro Sonnenfeld"
  ],
  "comment": "Published on Astronomy & Astrophysics. A 2-minute summary video is available at https://youtu.be/y5ffIZP9XHY",
  "journal": "A&A 659, A141 (2022)",
  "doi": "10.1051/0004-6361/202142786",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Context. The S\\'ersic profile is a widely-used model to describe the surface brightness distribution of galaxies. Spiral galaxies, however, are qualitatively different from a S\\'ersic model. Aims. The goal of this study is to assess how accurately the total flux and half-light radius of a galaxy with spiral arms can be recovered when fitted with a S\\'ersic profile. Methods. I selected a sample of bulge-dominated galaxies with spiral arms. Using photometric data from the Hyper Suprime-Cam survey, I estimated the contribution of the spiral arms to their total flux. Then I generated simulated images of galaxies with similar characteristics, fitted them with a S\\'ersic model, and quantified the error on the determination of the total flux and half-light radius. Results. Spiral arms can introduce biases on the photometry of galaxies in a way that depends on the underlying smooth surface brightness profile, the location of the arms, and the depth of the photometric data. A set of spiral arms accounting for 10% of the flux of a bulge-dominated galaxy typically causes the total flux and the half-light radius to be overestimated by 15% and 30%, respectively. This bias, however, is much smaller if the galaxy is disk-dominated. Conclusions. Galaxies with a prominent bulge and a non-zero contribution from spiral arms are the most susceptible to biases in the total flux and half-light radius, when fitted with a S\\'ersic profile. If photometric measurements with high accuracy are required, then measurements over finite apertures are to be preferred over global estimates of the flux.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2022-04-13T20:43:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spiral arms",
      "total flux",
      "sérsic photometry",
      "half-light radius",
      "sersic model"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}