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Galaxy Zoo: The properties of merging galaxies in the nearby Universe - local environments, colours, masses, star-formation rates and AGN activity

Abstract:
Following the study of Darg et al. (2009; hereafter D09a) we explore the environments, optical colours, stellar masses, star formation and AGN activity in a sample of 3003 pairs of merging galaxies drawn from the SDSS using visual classifications from the Galaxy Zoo project. While D09a found that the spiral-to-elliptical ratio in (major) mergers appeared higher than that of the global galaxy population, no significant differences are found between the environmental distributions of mergers and a randomly selected control sample. This makes the high occurrence of spirals in mergers unlikely to be an environmental effect and must, therefore, arise from differing time-scales of detectability for spirals and ellipticals. We find that merging galaxies have a wider spread in colour than the global galaxy population, with a significant blue tail resulting from intense star formation in spiral mergers. Galaxies classed as star-forming using their emission-line properties have average star-formation rates approximately doubled by the merger process though star formation is negligibly enhanced in merging elliptical galaxies. We conclude that the internal properties of galaxies significantly affect the time-scales over which merging systems can be detected (as suggested by recent theoretical studies) which leads to spirals being `over-observed' in mergers. We also suggest that the transition mass $3\times10^{10}{M}_{\astrosun}$, noted by \citet{kauffmann1}, below which ellipticals are rare could be linked to disc survival/destruction in mergers.
Publication status:
Published

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Publisher copy:
10.1111/j.1365-2966.2009.15786.x

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Journal:
Monthly Notices of the Royal Astronomical Society More from this journal
Volume:
401
Issue:
3
Pages:
1552-1563
Publication date:
2009-03-29
DOI:
EISSN:
1365-2966
ISSN:
0035-8711


Keywords:
Pubs id:
pubs:46186
UUID:
uuid:9a5940ff-0237-49a5-b489-053b464c9a05
Local pid:
pubs:46186
Source identifiers:
46186
Deposit date:
2012-12-19

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