Publication Date:
2013-04-13
Description:
Taking advantage of the ultradeep near-infrared imaging obtained with the Hubble Space Telescope on the Hubble Ultra Deep Field , we detect and explore for the first time the properties of the stellar haloes of two Milky Way-like galaxies at z ~ 1. We find that the structural properties of those haloes (size and shape) are similar to the ones found in the local Universe. However, these high- z stellar haloes are approximately three magnitudes brighter and exhibit bluer colours (( g – r ) 0.3 mag) than their local counterparts. The stellar populations of z ~ 1 stellar haloes are compatible with having ages 1 Gyr. This implies that the stars in those haloes were formed basically at 1 〈 z 〈 2. This result matches very well the theoretical predictions that locate most of the formation of the stellar haloes at those early epochs. A pure passive evolutionary scenario, where the stellar populations of our high- z haloes simply fade to match the stellar halo properties found in the local universe, is consistent with our data.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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