NEAR-INFRARED STRUCTURE OF FAST AND SLOW-ROTATING DISK GALAXIES

• Published in: The Astrophysical journal 2014-11, Vol.795 (2), p.1-40
• Main Authors: Schechtman-Rook, Andrew, Bershady, Matthew A
• Format: Article
• Language: English
• Subjects: Astronomical models; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATTENUATION; COLOR; Correlation; Disks; Galactic disk; Galactic structure; Galaxies; MASS; MILKY WAY; RADIANT HEAT TRANSFER; RESOLUTION; Spiral galaxies; Spirals; STARS; THREE-DIMENSIONAL CALCULATIONS; VELOCITY; VISIBLE RADIATION
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/795/2/136

We investigate the stellar disk structure of six nearby edge-on spiral galaxies using high-resolution JHK sub(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 super(-1) < V sub(rot) < 245 km s super(-1), and two with unusual morphologies. We find a wide diversity of disk structure. Of the fast-rotating (V sub(rot) > 150 km s super(-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 h sub(z) [lap] 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 sub(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 sub(Ks)/f sub(60 ) mu m [< or =, slant] 0.12 for integrated light, consistent with super-thin disks being regions of ongoing star-formation. Attenuation-corrected vertical color gradients in (J - K sub(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.