{
  "id": "2411.12564",
  "version": "v1",
  "published": "2024-11-19T15:28:24.000Z",
  "updated": "2024-11-19T15:28:24.000Z",
  "title": "CHANG-ES XXXV: Cosmic Ray Transport and Magnetic Field Structure of NGC 3556 at 3 GHz",
  "authors": [
    "Jianghui Xu",
    "Yang Yang",
    "Jiang-Tao Li",
    "Guilin Liu",
    "Judith Irwin",
    "Ralf-Jürgen Dettmar",
    "Michael Stein",
    "Theresa Wiegert",
    "Q. Daniel Wang",
    "Jayanne English"
  ],
  "comment": "17 pages, 10 figures, 4 tables, accepted for publication in ApJ",
  "categories": [
    "astro-ph.GA"
  ],
  "abstract": "Radio halos of edge-on galaxies are crucial for investigating cosmic ray propagation and magnetic field structures in galactic environments. We present VLA C-configuration S-band (2--4 GHz) observations of the spiral galaxy NGC 3556, a target from the Continuum Halos in Nearby Galaxies - an EVLA Survey (CHANG-ES). We estimate the thermal contribution to the radio emission from a combination of the H$\\alpha$ and mid-IR data, and employ Rotation Measure Synthesis to reveal the magnetic field structures. In our data, NGC 3556 exhibits a box-like radio halo extending nearly 7 kpc from the galactic plane. The scale height of the total S-band intensity in the halo is $1.68\\pm 0.29$ kpc, while that of the non-thermal intensity is $1.93\\pm 0.28$ kpc. Fitting the data to a 1-D cosmic-ray transport model, we find advection to describe the cosmic-ray propagation within the halo better than diffusion, with advection speeds of $245 \\pm 15$ km s$^{-1}$ and $205 \\pm 25$ km s$^{-1}$ above and below the disk, respectively. The magnetic field is detected patchily across the galaxy, displaying a toroidal configuration in the rotation measure map. The mean equipartition magnetic field strength is approximately $8.3\\ \\mu$G in the disk and $4.5\\ \\mu$G in the halo. In addition, a bubble-like structure extends nearly 3~kpc into the southern halo, aligned with the polarized intensity and H$\\alpha$ image, suggestive of superwinds generated by recent star formation feedback in the nuclear region.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-11-19T15:28:24.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "magnetic field structure",
      "cosmic ray transport",
      "chang-es xxxv",
      "mean equipartition magnetic field strength",
      "radio halo"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 17,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}