Mon. Not. R. Astron. Soc., 466, 1491-1512 (2017/April-1)
Diverse stellar haloes in nearby Milky Way mass disc galaxies.
HARMSEN B., MONACHESI A., BELL E.F., DE JONG R.S., BAILIN J., RADBURN-SMITH D.J. and HOLWERDA B.W.
Abstract (from CDS):
We have examined the resolved stellar populations at large galactocentric distances along the minor axis (from 10 kpc up to between 40 and 75 kpc), with limited major axis coverage, of six nearby highly inclined Milky Way (MW) mass disc galaxies using Hubble Space Telescope data from the Galaxy haloes, Outer discs, Substructure, Thick discs, and Star clusters (GHOSTS) survey. We select red giant branch stars to derive stellar halo density profiles. The projected minor axis density profiles can be approximated by power laws with projected slopes of -2 to -3.7 and a diversity of stellar halo masses of 1-6 x 109 M☉, or 2-14 per cent of the total galaxy stellar masses. The typical intrinsic scatter around a smooth power-law fit is 0.05-0.1 dex owing to substructure. By comparing the minor and major axis profiles, we infer projected axis ratios c/a at ∼25 kpc between 0.4and0.75. The GHOSTS stellar haloes are diverse, lying between the extremes charted out by the (rather atypical) haloes of the MW and M31. We find a strong correlation between the stellar halo metallicities and the stellar halo masses. We compare our results with cosmological models, finding good agreement between our observations and accretion-only models where the stellar haloes are formed by the disruption of dwarf satellites. In particular, the strong observed correlation between stellar halo metallicity and mass is naturally reproduced. Low-resolution hydrodynamical models have unrealistically high stellar halo masses. Current high-resolution hydrodynamical models appear to predict stellar halo masses somewhat higher than observed but with reasonable metallicities, metallicity gradients, and density profiles.
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
galaxies: evolution - galaxies: general - galaxies: haloes - galaxies: individual: (NGC 253, NGC 891, NGC 3031, NGC 4565, NGC 4945, NGC 7814) - galaxies: stellar content - galaxies: stellar content
View the reference in ADS
To bookmark this query, right click on this link: simbad:2017MNRAS.466.1491H and select 'bookmark this link' or equivalent in the popup menu