A new method for classifying galaxy SEDs from multiwavelength photometry

Wild, Vivienne; Almaini, Omar; Cirasuolo, Michele; Dunlop, Jim; McLure, Ross; Bowler, Rebecca; Ferreira, Joao; Bradshaw, Emma; Chuter, Robert; Hartley, Will

Abstract

We present a new method to classify the broad-band optical–near-infrared spectral energy distributions (SEDs) of galaxies using three shape parameters (super-colours) based on a principal component analysis of model SEDs. As well as providing a compact representation of the wide variety of SED shapes, the method allows for easy visualization of information loss and biases caused by the incomplete sampling of the rest-frame SED as a function of redshift. We apply the method to galaxies in the United Kingdom Infrared Telescope Infrared Deep Sky Survey Ultra Deep Survey with 0.9 < z < 1.2, and confirm our classifications by stacking rest-frame optical spectra for a fraction of objects in each class. As well as cleanly separating a tight red sequence from star-forming galaxies, three unusual populations are identifiable by their unique colours: very dusty star-forming galaxies with high metallicity and old mean stellar age; post-starburst galaxies which have formed _10 per cent of their mass in a recent unsustained starburst event; and metal-poor quiescent dwarf galaxies.We find that quiescent galaxies account for 45 per cent of galaxies with logM∗/M_ > 11, declining steadily to 13 per cent at logM∗/M_ = 10. The properties and mass function of the poststarburst galaxies are consistent with a scenario in which gas-rich mergers contribute to the growth of the low- and intermediate-mass range of the red sequence.

Citation

Wild, V., Almaini, O., Cirasuolo, M., Dunlop, J., McLure, R., Bowler, R., …Hartley, W. (in press). A new method for classifying galaxy SEDs from multiwavelength photometry. Monthly Notices of the Royal Astronomical Society, 440(2), https://doi.org/10.1093/mnras/stu212

• Journal Article Type: Article
• Acceptance Date: Jan 29, 2014
• Online Publication Date: Mar 28, 2014
• Deposit Date: Oct 6, 2017
• Publicly Available Date: Oct 6, 2017
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 440
• Issue: 2
• DOI: https://doi.org/10.1093/mnras/stu212
• Public URL: https://nottingham-repository.worktribe.com/output/724159
• Publisher URL: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stu212
• Contract Date: Oct 6, 2017