A new method for classifying galaxy SEDs from multiwavelength photometry

Michele Cirasuolo, Ross McLure, Rebecca Bowler, Joao Ferreira, James Dunlop

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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 greater than or similar to 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 log M*/M-circle dot > 11, declining steadily to 13 per cent at log M*/M-circle dot = 10. The properties and mass function of the post-starburst 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.

Original languageEnglish
Pages (from-to)1880-1898
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume440
Issue number2
DOIs
Publication statusPublished - May 2014

Keywords / Materials (for Non-textual outputs)

  • methods: statistical
  • galaxies: fundamental parameters
  • galaxies: luminosity function
  • mass function
  • galaxies: photometry
  • galaxies: statistics
  • galaxies: stellar content
  • DIGITAL-SKY-SURVEY
  • POST-STARBURST GALAXIES
  • STAR-FORMING GALAXIES
  • ULTRA-DEEP SURVEY
  • INDEPENDENT COMPONENT ANALYSIS
  • SPECTRAL ENERGY-DISTRIBUTIONS
  • ACTIVE GALACTIC NUCLEI
  • HIGH-REDSHIFT GALAXIES
  • MEDIUM-BAND SURVEY
  • WIDE-FIELD CAMERA

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