Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Early assembly of the most massive galaxies
AU - Collins, Chris A.
AU - Stott, John P.
AU - Hilton, Matt
AU - Kay, Scott T.
AU - Stanford, S. Adam
AU - Davidson, Michael
AU - Hosmer, Mark
AU - Hoyle, Ben
AU - Liddle, Andrew
AU - Lloyd-Davies, Ed
AU - Mann, Robert G.
AU - Mehrtens, Nicola
AU - Miller, Christopher J.
AU - Nichol, Robert C.
AU - Romer, A. Kathy
AU - Sahlén, Martin
AU - Viana, Pedro T P
AU - West, Michael J.
PY - 2009/4/2
Y1 - 2009/4/2
N2 - The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging. Stars begin to form relatively quickly in sub-galactic-sized building blocks called haloes which are subsequently assembled into galaxies. However, exactly when this assembly takes place is a matter of some debate. Here we report that the stellar masses of brightest cluster galaxies, which are the most luminous objects emitting stellar light, some 9 billion years ago are not significantly different from their stellar masses today. Brightest cluster galaxies are almost fully assembled 4-5 billion years after the Big Bang, having grown to more than 90 per cent of their final stellar mass by this time. Our data conflict with the most recent galaxy formation models based on the largest simulations of dark-matter halo development. These models predict protracted formation of brightest cluster galaxies over a Hubble time, with only 22 per cent of the stellar mass assembled at the epoch probed by our sample. Our findings suggest a new picture in which brightest cluster galaxies experience an early period of rapid growth rather than prolonged hierarchical assembly.
AB - The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging. Stars begin to form relatively quickly in sub-galactic-sized building blocks called haloes which are subsequently assembled into galaxies. However, exactly when this assembly takes place is a matter of some debate. Here we report that the stellar masses of brightest cluster galaxies, which are the most luminous objects emitting stellar light, some 9 billion years ago are not significantly different from their stellar masses today. Brightest cluster galaxies are almost fully assembled 4-5 billion years after the Big Bang, having grown to more than 90 per cent of their final stellar mass by this time. Our data conflict with the most recent galaxy formation models based on the largest simulations of dark-matter halo development. These models predict protracted formation of brightest cluster galaxies over a Hubble time, with only 22 per cent of the stellar mass assembled at the epoch probed by our sample. Our findings suggest a new picture in which brightest cluster galaxies experience an early period of rapid growth rather than prolonged hierarchical assembly.
U2 - 10.1038/nature07865
DO - 10.1038/nature07865
M3 - Journal article
AN - SCOPUS:63849322268
VL - 458
SP - 603
EP - 606
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7238
ER -