Feedback and Recycled Wind Accretion: Assembling the z=0 Galaxy Mass Function - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




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Abstract: We analyse cosmological hydrodynamic simulations that includeobservationally-constrained prescriptions for galactic outflows. If thesesimulated winds accurately represent winds in the real Universe, then materialpreviously ejected in winds provides the dominant source of gas infall for newstar formation at redshifts z<1. This recycled wind accretion, or wind mode,provides a third physically distinct accretion channel in addition to the -hot-and -cold- modes emphasised in recent theoretical studies. Because of theinteraction between outflows and gas in and around halos, the recyclingtimescale of wind material t rec is shorter in higher-mass systems, whichreside in denser gaseous environments. In these simulations, this differentialrecycling plays a central role in shaping the present-day galaxy stellar massfunction GSMF. If we remove all particles that were ever ejected in a wind,then the predicted GSMFs are much steeper than observed; galaxy masses aresuppressed both by the direct removal of gas and by the hydrodynamic heating oftheir surroundings, which reduces subsequent infall. With wind recyclingincluded, the simulation that incorporates our favoured momentum-driven windscalings reproduces the observed GSMF for stellar masses 10^9 < M < 5x10^10Msolar. At higher masses, wind recycling leads to excessive galaxy masses andexcessive star formation rates relative to observations. In these massivesystems, some quenching mechanism must suppress the re-accretion of gas ejectedfrom star-forming galaxies. In short, as has long been anticipated, the form ofthe GSMF is governed by outflows; the unexpected twist here for our simulatedwinds is that it is not primarily the ejection of material but how the ejectedmaterial is re-accreted that governs the GSMF.



Author: Benjamin D. Oppenheimer, Romeel Davé, Dušan Kereš, Mark Fardal, Neal Katz, Juna A. Kollmeier, David H. Weinberg

Source: https://arxiv.org/







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