The interstellar medium and star formation in local galaxies: variations of the star formation law in simulations
Author
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Becerra Saavedra, Fernando Felipe
es_CL
Author
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Escala Astorquiza, Andrés
Admission date
dc.date.accessioned
2015-01-06T19:07:31Z
Available date
dc.date.available
2015-01-06T19:07:31Z
Publication date
dc.date.issued
2014
Cita de ítem
dc.identifier.citation
The Astrophysical Journal, 786:56 (13 pp), 2014 May 1
en_US
Identifier
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doi:10.1088/0004-637X/786/1/56
Identifier
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https://repositorio.uchile.cl/handle/2250/126936
General note
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Artículo de publicación ISI
en_US
Abstract
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We use the adaptive mesh refinement code Enzo to model the interstellar medium (ISM) in isolated local disk
galaxies. The simulation includes a treatment for star formation and stellar feedback. We get a highly supersonic
turbulent disk, which is fragmented at multiple scales and characterized by a multi-phase ISM. We show that a
Kennicutt–Schmidt relation only holds when averaging over large scales. However, values of star formation rates
and gas surface densities lie close in the plot for any averaging size. This suggests an intrinsic relation between
stars and gas at cell-size scales, which dominates over the global dynamical evolution. To investigate this effect, we
develop a method to simulate the creation of stars based on the density field from the snapshots, without running the
code again.We also investigate how the star formation law is affected by the characteristic star formation timescale,
the density threshold, and the efficiency considered in the recipe.We find that the slope of the law varies from ∼1.4
for a free-fall timescale, to ∼1.0 for a constant depletion timescale. We further demonstrate that a power law is
recovered just by assuming that the mass of the new stars is a fraction of the mass of the cell m = ρgasΔx3, with
no other physical criteria required. We show that both efficiency and density threshold do not affect the slope, but
the right combination of them can adjust the normalization of the relation, which in turn could explain a possible
bi-modality in the law.
en_US
Patrocinador
dc.description.sponsorship
F.B. acknowledges support
from Programa Nacional de Becas de Postgrado (grant D-
22100632). A.E. acknowledges partial support from the Center
for Astrophysics and Associated Technologies CATA (PFB
06), Anillo de Ciencia y Tecnolog´ıa (Project ACT1101), and
Proyecto Regular Fondecyt (grant 1130458).