Volume 596, December 2016
|Number of page(s)||23|
|Published online||23 November 2016|
Influence of galaxy stellar mass and observed wavelength on disc breaks in S4G, NIRS0S, and SDSS data⋆
Astronomy Research Unit, 90014 University of Oulu, PO Box 3000, Oulu, Finland
Received: 26 February 2016
Accepted: 22 August 2016
Context. Breaks in the surface brightness profiles in the outer regions of galactic discs are thought to have formed by various internal (e.g. bar resonances) and external (e.g. galaxy merging) processes. By studying the disc breaks we aim to better understand what processes are responsible for the evolution of the outer discs of galaxies, and galaxies in general.
Aims. We use a large well-defined sample to study how common the disc breaks are, and whether their properties depend on galaxy mass. By using both optical and infrared data we study whether the observed wavelength affects the break features as a function of galaxy mass and Hubble type.
Methods. We studied the properties of galaxy discs using radial surface brightness profiles of 753 galaxies, obtained from the 3.6 μm images of the Spitzer Survey of Stellar Structure in Galaxies (S4G), and the Ks-band data from the Near InfraRed S0-Sa galaxy Survey (NIRS0S), covering a wide range of galaxy morphologies (−2 ≤ T ≤ 9) and stellar masses (8.5 ≲ log 10(M∗/M⊙) ≲ 11). In addition, optical Sloan Digital Sky Survey (SDSS) or Liverpool telescope data was used for 480 of these galaxies.
Results. We find that in low-mass galaxies the single exponential profiles (Type I) are most common, and that their fraction decreases with increasing galaxy stellar mass. The fraction of down-bending (Type II) profiles increases with stellar mass, possibly due to more common occurrence of bar resonance structures. The up-bending (Type III) profiles are also more common in massive galaxies. The observed wavelength affects the scalelength of the disc of every profile type. Especially the scalelength of the inner disc (hi) of Type II profiles increases from infrared to u-band on average by a factor of ~2.2. Consistent with the previous studies, but with a higher statistical significance, we find that Type II outer disc scalelengths (ho) in late-type and low mass galaxies (T > 4, log 10(M∗/M⊙) ≲ 10.5) are shorter in bluer wavelengths, possibly due to stellar radial migration populating the outer discs with older stars. In Type III profiles ho are larger in the u-band, hinting to the presence of young stellar population in the outer disc. While the observed wavelength affects the disc parameters, it does not significantly affect the profile type classification in our sample. Our results indicate that the observed wavelength is a significant factor when determining the profile types in very low mass dwarf galaxies, for which more Type II profiles have been previously found using optical data.
Key words: galaxies: evolution / galaxies: structure / galaxies: statistics
Full Tables 1 and 3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A25
© ESO, 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.