Abstract.
We model in simple terms the angular momentum (J) problem of galaxy formation in CDM, and identify the key elements of a scenario that can solve it. The buildup of J is modeled via dynamical friction and tidal stripping in mergers. This reveals how over-cooling in incoming halos leads to transfer of J from baryons to dark matter (DM), in conflict with observations. By incorporating a simple recipe of supernova feedback, we match the observed J distribution in disks. Gas removal from small incoming halos, which make the low-J component of the product, eliminates the low-J baryons. Partial heating and puffing-up of the gas in larger incoming halos, combined with tidal stripping, reduces the J loss of baryons. This implies a higher baryonic spin for lower mass halos. The observed low baryonic fraction in dwarf galaxies is used to calibrate the characteristic velocity associated with supernova feedback, yielding \(V_{\rm fb} \sim 100\) km s-1, within the range of theoretical expectations. The model then reproduces the observed distribution of spin parameter among dwarf and bright galaxies, as well as the J distribution inside these galaxies. This suggests that the model captures the main features of a full scenario for resolving the spin crisis.
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Dekel, A., Maller, A.H. Resolving the Spin Crisis: Mergers and Feedback. In: Bender, R., Renzini, A. (eds) The Mass of Galaxies at Low and High Redshift. ESO ASTROPHYSICS SYMPOSIA. Springer, Berlin, Heidelberg. https://doi.org/10.1007/10899892_41
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DOI: https://doi.org/10.1007/10899892_41
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-00205-5
Online ISBN: 978-3-540-36191-6
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