A New Empirical Method to Infer the Starburst History of the Universe from Local Galaxy Properties - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: The centers of bulges are formed dissipationally via gas inflows over shorttimescales: the -starburst- mode of star formation SF. Recent work has shownthat detailed observations can be used to separate the stellar mass profile ofthese -burst relic- components in local systems. Together with the assumptionthat some Kennicutt-Schmidt law holds, and that the burst was indeed adissipational gas-rich event, we show that the observed profiles can beinverted to obtain the time and space-dependent SF history of each burst.Performing this with a large sample of well-studied spheroids, we show that theimplied bursts scale in magnitude, mass, peak SFR, and spatial extent withgalaxy mass in simple manner, and provide fits to these correlations. Burstmasses are ~10% the total spheroid mass; timescales a mass-independent ~10^8yr; peak SFR ~M burst-t burst; and they decay in power-law fashion ~t^-2.4.Sizes are ~0.1 R espheroid, but grow with time. Combined with measurements ofthe nuclear stellar population ages of these systems i.e. burst times, it ispossible to re-construct the burst contribution to the distribution of SFRs andIR luminosity functions at all redshifts. The burst LF agrees well withobserved IR LFs at the brightest luminosities, at z=0-2. At low-L, bursts arealways unimportant; the transition to their importance increases from ULIRGluminosities at z~0 to HyLIRG luminosities at z~2. At all redshifts, bursts area small fraction ~5-10% of the total SFR density. We discuss possibleimplications of tension between maximum relic stellar mass densities in massivesystems, and estimated number counts of brightest sub-millimeter galaxies.



Autor: Philip F. Hopkins Berkeley, Lars Hernquist CfA

Fuente: https://arxiv.org/







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