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Title: Galaxy and mass assembly (GAMA): refining the local galaxy merger rate using morphological information
Author: Casteels, Kevin R. V
Conselice, Christopher J.
Bamford, Steven P.
Salvador Solé, Eduard
Norberg, Peder R.
Agius, Nicola K.
Baldry, Ivan
Brough, Sarah
Brown, Michael J. I.
Drinkwater, Michael J.
Driver, Simon P
Graham, Alister W.
Bland Hawthorn, Joss
Hopkins, Andrew M.
Kelvin, Lee S.
López Sánchez, Angel R.
Loveday, Jon
Robotham, Aaron S. G.
Vázquez Mata, José A.
Keywords: Evolució de les galàxies
Galaxies evolution
Issue Date: Dec-2014
Publisher: Royal Astronomical Society
Abstract: We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass dependent merger fraction and merger rate using galaxy pairs and the CAS structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies, and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to $M_{*} = 10^{8}M_{\odot}$ with mass ratios of $<$100:1 and line of sight velocity differences of $\Delta V<500$ km s$^{-1}$. We find a significant increase in mean asymmetries for projected separations less than the sum of the individual galaxy's Petrosian 90 radii. For systems in major merger pairs with mass ratios of $<$4:1 both galaxies in the pair show a strong increase in asymmetry, while in minor merger systems (with mass ratios of $>$4:1) the lower mass companion becomes highly asymmetric, while the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass dependent major merger fraction is fairly constant at $\sim1.3-2\%$ between $10^{9.5}<M_{*}<10^{11.5} M_{\odot}$, and increases to $\sim4\%$ at lower masses. When the observability time scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total co-moving volume major merger rate over the range $10^{8.0}<M_{*}<10^{11.5} M_{\odot}$ is $(1.2 \pm 0.5) \times 10^{-3}$ $h^{3}_{70}$ Mpc$^{-3}$ Gyr$^{-1}$.
Note: Reproducció del document publicat a:
It is part of: Monthly Notices of the Royal Astronomical Society, 2014, vol. 445, num. 2, p. 1157-1169
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ISSN: 0035-8711
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)
Publicacions de projectes de recerca finançats per la UE

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