THE THICK DISK IN THE GALAXY NGC 4244 FROM S⁴G IMAGING

Abstract

If thick disks are ubiquitous and a natural product of disk galaxy formation and/or evolution processes, all
\nundisturbed galaxies that have evolved during a significant fraction of a Hubble time should have a thick disk. The
\nlate-type spiral galaxy NGC 4244 has been reported as the only nearby edge-on galaxy without a confirmed thick
\ndisk. Using data from the Spitzer Survey of Stellar Structure in Galaxies (S^4G) we have identified signs of two disk
\ncomponents in this galaxy. The asymmetries between the light profiles on both sides of the mid-plane of NGC 4244
\ncan be explained by a combination of the galaxy not being perfectly edge-on and a certain degree of opacity of
\nthe thin disk. We argue that the subtlety of the thick disk is a consequence of either a limited secular evolution in
\nNGC 4244, a small fraction of stellar material in the fragments which built the galaxy, or a high amount of gaseous
\naccretion after the formation of the galaxy.