TY - JOUR
T1 - Origin of the joint distribution of structural parameters in disc galaxies
AU - Dutton, Aaron A.
AU - Van Den Bosch, Frank C.
AU - Courteau, Stéphane
AU - Dekel, Avishai
N1 - Publisher Copyright:
© 2004 Sissa Medialab Srl. All rights reserved.
PY - 2004
Y1 - 2004
N2 - We use a simple model of disc-galaxy formation in the ΔCDM cosmology to simultaneously reproduce the slopes, zero-points, scatter and uncorrelated residuals in the observed velocityluminosity (VL) and radius-luminosity (RL) relations. Observed I-band luminosities are converted to stellar masses using the IMF-dependent relation between stellar mass-To-light ratio, ϒ, and color. The model treats halo concentration, spin parameter, and disc mass fraction as independent log-normal random variables. Our main conclusion is that the VL and RL zero-points and the uncorrelated residuals can only be reproduced simultaneously if adiabatic contraction is avoided. One or the other could be fixed by appealing to unrealistic values for ϒ, halo concentration c, and spin parameter λ, but not all together. The small VL scatter is naturally determined by the predicted scatter in c and in ϒ, quite independent of the large scatter in λ. However, the RL scatter, driven by the scatter in λ, can be as low as observed only if σlnλ ≃0. 25, about half the value predicted for CDM haloes. This may indicate that discs form in a special subset of haloes. The VL slope is reproduced once star formation occurs only above a threshold surface density, and the RL slope implies that the disc mass fraction is increasing with halo mass, consistent with feedback effects. A model that incorporates the above ingredients provides a simultaneous fit to all the observed features. In particular, the elimination of adiabatic contraction allows 80% disc contribution to the observed rotation velocity of bright discs at 2.2 disc scale lengths. The lack of halo contraction may indicate that disc formation is not as smooth as typically envisioned, but instead may involve clumpy, cold streams.
AB - We use a simple model of disc-galaxy formation in the ΔCDM cosmology to simultaneously reproduce the slopes, zero-points, scatter and uncorrelated residuals in the observed velocityluminosity (VL) and radius-luminosity (RL) relations. Observed I-band luminosities are converted to stellar masses using the IMF-dependent relation between stellar mass-To-light ratio, ϒ, and color. The model treats halo concentration, spin parameter, and disc mass fraction as independent log-normal random variables. Our main conclusion is that the VL and RL zero-points and the uncorrelated residuals can only be reproduced simultaneously if adiabatic contraction is avoided. One or the other could be fixed by appealing to unrealistic values for ϒ, halo concentration c, and spin parameter λ, but not all together. The small VL scatter is naturally determined by the predicted scatter in c and in ϒ, quite independent of the large scatter in λ. However, the RL scatter, driven by the scatter in λ, can be as low as observed only if σlnλ ≃0. 25, about half the value predicted for CDM haloes. This may indicate that discs form in a special subset of haloes. The VL slope is reproduced once star formation occurs only above a threshold surface density, and the RL slope implies that the disc mass fraction is increasing with halo mass, consistent with feedback effects. A model that incorporates the above ingredients provides a simultaneous fit to all the observed features. In particular, the elimination of adiabatic contraction allows 80% disc contribution to the observed rotation velocity of bright discs at 2.2 disc scale lengths. The lack of halo contraction may indicate that disc formation is not as smooth as typically envisioned, but instead may involve clumpy, cold streams.
UR - http://www.scopus.com/inward/record.url?scp=85049676420&partnerID=8YFLogxK
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AN - SCOPUS:85049676420
SN - 1824-8039
VL - 2004-October
JO - Proceedings of Science
JF - Proceedings of Science
M1 - 036
T2 - 2004 Baryons in Dark Matter Halos, BDMH 2004
Y2 - 5 October 2004 through 9 October 2004
ER -