TY - JOUR
T1 - Galaxy and mass assembly (GAMA)
T2 - Merging galaxies and their properties
AU - De Propris, Roberto
AU - Baldry, Ivan K.
AU - Bland-Hawthorn, Joss
AU - Brough, Sarah
AU - Driver, Simon P.
AU - Hopkins, Andrew M.
AU - Kelvin, Lee
AU - Loveday, Jon
AU - Phillipps, Steve
AU - Robotham, Aaron S G
PY - 2014
Y1 - 2014
N2 - We derive the close pair fractions and volume merger rates for galaxies in the Galaxy and Mass Assembly (GAMA) survey with -23 < Mr < -17 (ΩM = 0.27, ΩΔ = 0.73, H0 = 100 km s-1 Mpc-1) at 0.01 < z<0.22 (look-back time of <2 Gyr). The merger fraction is approximately 1.5 per cent Gyr-1 at all luminosities (assuming 50 per cent of pairs merge) and the volume merger rate is ≈3.5 × 10-4 Mpc-3 Gyr-1. We examine how the merger rate varies by luminosity and morphology. Dry mergers (between red/spheroidal galaxies) are found to be uncommon and to decrease with decreasing luminosity. Fainter mergers are wet, between blue/discy galaxies. Damp mergers (one of each type) follow the average of dry and wetmergers. In the brighter luminosity bin (-23<Mr <-20), the merger rate evolution is flat, irrespective of colour or morphology, out to z ~ 0.2. The makeup of the merging population does not appear to change over this redshift range. Galaxy growth by major mergers appears comparatively unimportant and dry mergers are unlikely to be significant in the buildup of the red sequence over the past 2 Gyr. We compare the colour, morphology, environmental density and degree of activity (BPT class, Baldwin, Phillips & Terlevich) of galaxies in pairs to those of more isolated objects in the same volume. Galaxies in close pairs tend to be both redder and slightly more spheroid dominated than the comparison sample. We suggest that this may be due to 'harassment' in multiple previous passes prior to the current close interaction. Galaxy pairs do not appear to prefer significantly denser environments. There is no evidence of an enhancement in the AGN fraction in pairs, compared to other galaxies in the same volume.
AB - We derive the close pair fractions and volume merger rates for galaxies in the Galaxy and Mass Assembly (GAMA) survey with -23 < Mr < -17 (ΩM = 0.27, ΩΔ = 0.73, H0 = 100 km s-1 Mpc-1) at 0.01 < z<0.22 (look-back time of <2 Gyr). The merger fraction is approximately 1.5 per cent Gyr-1 at all luminosities (assuming 50 per cent of pairs merge) and the volume merger rate is ≈3.5 × 10-4 Mpc-3 Gyr-1. We examine how the merger rate varies by luminosity and morphology. Dry mergers (between red/spheroidal galaxies) are found to be uncommon and to decrease with decreasing luminosity. Fainter mergers are wet, between blue/discy galaxies. Damp mergers (one of each type) follow the average of dry and wetmergers. In the brighter luminosity bin (-23<Mr <-20), the merger rate evolution is flat, irrespective of colour or morphology, out to z ~ 0.2. The makeup of the merging population does not appear to change over this redshift range. Galaxy growth by major mergers appears comparatively unimportant and dry mergers are unlikely to be significant in the buildup of the red sequence over the past 2 Gyr. We compare the colour, morphology, environmental density and degree of activity (BPT class, Baldwin, Phillips & Terlevich) of galaxies in pairs to those of more isolated objects in the same volume. Galaxies in close pairs tend to be both redder and slightly more spheroid dominated than the comparison sample. We suggest that this may be due to 'harassment' in multiple previous passes prior to the current close interaction. Galaxy pairs do not appear to prefer significantly denser environments. There is no evidence of an enhancement in the AGN fraction in pairs, compared to other galaxies in the same volume.
KW - Galaxies: Formation
KW - Galaxies: Interactions
UR - http://www.scopus.com/inward/record.url?scp=84908420634&partnerID=8YFLogxK
U2 - 10.1093/mnras/stu1452
DO - 10.1093/mnras/stu1452
M3 - Article
AN - SCOPUS:84908420634
SN - 0035-8711
VL - 444
SP - 2200
EP - 2211
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -