The frequency of anomalously red galaxies in SDSS clusters

Shearman, O.; Pimbblet, K. A.

Abstract

We present a systematic photometric search for spectroscopically confirmed anomalously red galaxies members of 748 low redshift clusters between 0.03 < z < 0.17 from the SDSS-C4 cluster catalogue (Miller et al. 2005). For each cluster we spectroscopically determine cluster membership, construct a colour-magnitude diagram and fit the red sequence using a robust bi-weight fit.We define an “anomalously red galaxy” as having a (g− r) colour of greater than 3σ redward of the fitted cluster colour-magnitude relation.We find that of 7485 galaxies at r ≤ 17.77 in (g− r), 7 galaxies are anomalously red – 0.0935 per cent of all galaxies in our sample. We show that two of the red outliers are caused by red contamination from nearby sources and are therefore not intrinsically anomalous red. However, 5 have no underlying cause to be so red and we speculate that they may have a high internal dust content. These intrinsically red galaxies are rare – comprising no more than 0.0668 per cent of all cluster galaxies. Most are morphologically early type galaxies, with a few probable late type galaxies that are viewed edge-on and one low surface brightness late type. One of our anomalously red galaxies appears to be a dust-shrouded starburst and we speculate that this may be a unique galaxy amoungst this galaxy set.

Citation

Shearman, O., & Pimbblet, K. A. (2014). The frequency of anomalously red galaxies in SDSS clusters. Publications / Astronomical Society of Australia, 31, Article ARTN e038. https://doi.org/10.1017/pasa.2014.34

• Journal Article Type: Article
• Acceptance Date: Aug 30, 2014
• Online Publication Date: Sep 30, 2014
• Publication Date: Sep 30, 2014
• Deposit Date: Aug 28, 2015
• Journal: Publications of the Astronomical Society of Australia
• Print ISSN: 1323-3580
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 31
• Article Number: ARTN e038
• DOI: https://doi.org/10.1017/pasa.2014.34
• Keywords: Galaxies -- clusters -- general, Galaxies -- elliptical and lenticular, cD, Galaxies -- photometry, Galaxies -- stellar content, Hertzsprung-Russell and C-M diagrams
• Public URL: https://hull-repository.worktribe.com/output/378175
• Publisher URL: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9363076&fulltextType=RA&fileId=S1323358014000344
• Additional Information: This is a description of an article which has been published in: Publications of the Astronomical Society of Australia, 2014, v.31.
• Contract Date: Aug 28, 2015