Near-infrared Structure of Fast and Slow-rotating Disk Galaxies

Type Journal Article
Names Andrew Schechtman-Rook, Matthew A. Bershady
Publication The Astrophysical Journal
Volume 795
Issue 2
Pages 136
Journal Abbreviation The Astrophysical Journal
Date November 1, 2014
DOI 10.1088/0004-637X/795/2/136
ISSN 0004-637X
Library Catalog
Abstract We investigate the stellar disk structure of six nearby edge-on spiral galaxies using high-resolution JHK s-band images and three-dimensional radiative transfer models. To explore how mass and environment shape spiral disks, we selected galaxies with rotational velocities between 69 km s–1 rot < 245 km s–1, and two with unusual morphologies. We find a wide diversity of disk structure. Of the fast-rotating (V rot > 150 km s–1) galaxies, only NGC 4013 has the super-thin+thin+thick nested disk structure seen in NGC 891 and the Milky Way, albeit with decreased oblateness, while NGC 1055, a disturbed massive spiral galaxy, contains disks with hz <~ 200 pc. NGC 4565, another fast-rotator, contains a prominent ring at a radius ~5 kpc but no super-thin disk. Despite these differences, all fast-rotating galaxies in our sample have inner truncations in at least one of their disks. These truncations lead to Freeman Type II profiles when projected face-on. Slow-rotating galaxies are less complex, lacking inner disk truncations and requiring fewer disk components to reproduce their light distributions. Super-thin disk components in undisturbed disks contribute ~25% of the total K s-band light, up to that of the thin-disk contribution. The presence of super-thin disks correlates with infrared flux ratios; galaxies with super-thin disks have f{K_s}/f60 μ m ≤ 0.12 for integrated light, consistent with super-thin disks being regions of ongoing star-formation. Attenuation-corrected vertical color gradients in (J – K s) correlate with the observed disk structure and are consistent with population gradients with young-to-intermediate ages closer to the mid-plane, indicating that disk heating—or cooling—is a ubiquitous phenomenon.
Tags GALAXIES: STELLAR CONTENT, galaxies: individual: NGC 522 NGC 891 NGC 1055 NGC 4013 NGC 4144 NGC 4244 NGC 4565, galaxies: spiral
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