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Title: THE RADIAL METALLICITY GRADIENTS IN THE MILKY WAY THICK DISK AS FOSSIL SIGNATURES OF A PRIMORDIAL CHEMICAL DISTRIBUTION

In this Letter we examine the evolution of the radial metallicity gradient induced by secular processes, in the disk of an N-body Milky Way-like galaxy. We assign a [Fe/H] value to each particle of the simulation according to an initial, cosmologically motivated, radial chemical distribution and let the disk dynamically evolve for ∼6 Gyr. This direct approach allows us to take into account only the effects of dynamical evolution and to gauge how and to what extent they affect the initial chemical conditions. The initial [Fe/H] distribution increases with R in the inner disk up to R ≈ 10 kpc and decreases for larger R. We find that the initial chemical profile does not undergo major transformations after ∼6 Gyr of dynamical evolution. The final radial chemical gradients predicted by the model in the solar neighborhood are positive and of the same order as those recently observed in the Milky Way thick disk. We conclude that (1) the spatial chemical imprint at the time of disk formation is not washed out by secular dynamical processes and (2) the observed radial gradient may be the dynamical relic of a thick disk originated from a stellar population showing a positive chemical radial gradientmore » in the inner regions.« less
Authors:
; ; ; ;  [1] ;  [2]
  1. INAF-Osservatorio Astrofisico di Torino (Italy)
  2. Dipartimento di Fisica, Università di Torino, Torino (Italy)
Publication Date:
OSTI Identifier:
22365936
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 784; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; ELEMENT ABUNDANCE; GALACTIC EVOLUTION; METALLICITY; MILKY WAY; TRANSFORMATIONS