The cosmic evolution of the IMF under the Jeans conjecture with implications for massive galaxies
MetadataShow full item record
We examine the cosmic evolution of a stellar initial mass function (IMF) in galaxies that varies with the Jeans mass in the interstellar medium, paying particular attention to the K-band stellar mass-to-light ratio (M/LK) of present-epoch massive galaxies. We calculate the typical Jeans mass using high-resolution hydrodynamic simulations coupled with a fully radiative model for the interstellar medium (ISM), which yields a parametrization of the IMF characteristic mass as a function of galaxy star formation rate (SFR).We then calculate the star formation histories of galaxies utilizing an equilibrium galaxy growth model coupled with constraints on the star formation histories set by abundance matching models. We find that at early times, energetic coupling between dust and gas drives warm conditions in the ISM, yielding bottom-light/topheavy IMFs associated with large ISM Jeans masses for massive star-forming galaxies. Owing to the remnants of massive stars that formed during the top-heavy phases at early times, the resultant M/LK(σ) in massive galaxies at the present epoch is increased relative to the nonvarying IMF case. At late times, lower cosmic ray fluxes allow for cooler ISM temperatures in massive galaxies, and hence newly formed clusters will exhibit bottom-heavy IMFs, further increasing M/LK(σ). Our central result is hence that a given massive galaxy may go through both top-heavy and bottom-heavy IMF phases during its lifetime, though the bulk of the stars form during a top-heavy phase. Qualitatively, the variations in M/LK(σ) with galaxy mass are in agreement with observations; however, our model may not be able to account for bottom-heavy mass functions as indicated by stellar absorption features.
Showing items related by title, author, creator and subject.
Wylezalek, D.; Vernet, J.; De Breuck, C.; Stern, D.; Galametz, A.; Seymour, N.; Jarvis, Matt; Barthel, P.; Drouart, G.; Rottgering, H.J.A.; Greve, T.R.; Haas, M.; Hatch, N.; Ivison, R.J.; Lehnert, M.; Meisenheimer, K.; Miley, G.; Nesvadba, N.; Stevens, J.A. (Oxford University Press, 2013)We present Herschel observations at 70, 160, 250, 350 and 500 μm of the environment of the radio galaxy 4C+41.17 at z = 3.792. About 65 per cent of the extracted sources are securely identified with mid-infrared sources ...
Dave, Romeel; Katz, Neal; Oppernheimer, Benjamin D.; Kollmeier, Juna A.; Weinberg, David H. (Oxford University Press, 2013)We examine the global HI properties of galaxies in quarter billion particle cosmological simulations using GADGET-2, focusing on howgalactic outflows impactHI content.We consider four outflow models, including a new one ...
Finlator, Kristian; Muñoz, Joseph A.; Dave, Romeel; Oppenheimer, B. D.; Peng Oh, S.; Özel, Feryal (Oxford University Press, 2013)We use a radiation hydrodynamic simulation of the hydrogen reionization epoch to study OI absorbers at z ∼ 6. The intergalactic medium (IGM) is reionized before it is enriched; hence, OI absorption originates within dark ...