English

Candidate List of Edge-on Galaxies with Substantial Extraplanar Dust

Astrophysics of Galaxies 2018-12-05 v1

Abstract

We present a list of edge-on galaxies that might have substantial extraplanar dust. Twenty-three edge-on galaxies were selected as target galaxies from an edge-on galaxy catalog, and their Galaxy Evolution Explorer far-ultraviolet images were fitted with three dimensional radiative transfer galaxy model. The galaxy model is described by two disks: one for the light source and the other for the dust. The best-fit parameters were found by employing a global optimization method, called differential evolution. To find the galaxies with substantial extraplanar dust using the best-fit parameters, we plotted the ratio of scale-height to galactic diameter: zs/D25,phz_s/D_{25,ph} (light source) vs zd/D25,phz_d/D_{25,ph} (dust). We found that 17 and 6 galaxies fall on the region of (zs/D25,ph×100)>0.2(z_s/D_{25,ph}\times100)>0.2 and (zs/D25,ph×100)<0.2(z_s/D_{25,ph}\times100)<0.2, respectively. The former is named as "high-group" and the latter is named as "low-group." We conclude that "high-group" is likely to be the galaxies with substantial extraplanar dust, while "low-group" is likely to be the ones with little extraplanar dust, i.e. typical galactic thin disk, based on the following points: (1) the relative positions of "high-group" and "low-group" on the plot zs/D25,phz_s/D_{25,ph} vs zd/D25,phz_d/D_{25,ph} with respect to the reference values from optical radiative transfer studies; (2) the lower scale-height of the young stellar population than the old stellar population; and (3) a test result that shows the existence of extraplanar dust makes zsz_s and zdz_d overestimated in the fitting results. We also examined the dependence of the group separation on the surface density of far-ultraviolet luminosity (LFUV/D25,ph2L_{FUV}/D^2_{25,ph}), but found no strong dependence.

Keywords

Cite

@article{arxiv.1809.08392,
  title  = {Candidate List of Edge-on Galaxies with Substantial Extraplanar Dust},
  author = {Jong-Ho Shinn},
  journal= {arXiv preprint arXiv:1809.08392},
  year   = {2018}
}

Comments

48 pages, 29 figures, 4 tables, ApJS in press