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Flat metallicity profiles in rotating dwarf galaxies

Joeri Schroyen (UGent) , Sven De Rijcke (UGent) and Sander Valcke (UGent)
(2011) EAS Publications Series. 48. p.407-409
Author
Organization
Abstract
Dwarf irregulars (dlrr) and flat, rotating dwarf ellipticals (dE) generally possess flat metallicity profiles while round dEs show strong metallicity gradients (Koleva et al. 2009). Unlike dEs, dlrrs also exhibit ongoing star formation (SF) (Dolphin et al. 2005), in most cases compatible with a continuous star formation history (SFH). We show results based on a large suite of Nbody-SPH simulations of flat dwarf galaxies, both rotating and non-rotating, performed with a modified version of GADGET2. They have a range of masses, flattenings and rotations speeds and are based on the spherical models of (Valcke et al. 2008). Specifically, we want to see if it is possible to reproduce these characteristics in isolated DG models. These simulations show that using rotation to flatten a dwarf galaxy is particularly efficient in turning a so-called "breathing" SFH (Valcke et al. 2008) into a more continuous SFH, and in producing flat metallicity profiles. Non-rotating dEs in a flattened dark-matter halo are not able to reproduce these characteristics. Thus, it appears that rotation is key to reproducing the observed characteristics. Rotation causes a "centrifugal barrier" which slows down the infall of gas, so that the low-level star formation is not centrally concentrated but occurs galaxy-wide, and in this way also prevents large-scale oscillations in the SFR. This mechanism of smearing out the star formation in time and space proves to be the principal reason for the flat metallicity profiles, instead of the often referred to "fountain mechanism" (De Young & Heckman 1994; Barazza & Binggeli 2002; Mac Low & Ferrara 1999; Ferrara & Tolstoy 2000). We therefore propose a "centrifugal barrier mechanism" which is able to explain the observations.
Keywords
dark matter, star formation, galaxies, ELLIPTIC GALAXIES, EVOLUTION

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MLA
Schroyen, Joeri, Sven De Rijcke, and Sander Valcke. “Flat Metallicity Profiles in Rotating Dwarf Galaxies.” EAS Publications Series. Ed. M Koleva, P Prugniel, & I Vauglin. Vol. 48. Les Ulis, France: EDP Sciences, 2011. 407–409. Print.
APA
Schroyen, J., De Rijcke, S., & Valcke, S. (2011). Flat metallicity profiles in rotating dwarf galaxies. In M Koleva, P. Prugniel, & I. Vauglin (Eds.), EAS Publications Series (Vol. 48, pp. 407–409). Presented at the Conference on a Universe of Dwarf Galaxies (CRAL 2010), Les Ulis, France: EDP Sciences.
Chicago author-date
Schroyen, Joeri, Sven De Rijcke, and Sander Valcke. 2011. “Flat Metallicity Profiles in Rotating Dwarf Galaxies.” In EAS Publications Series, ed. M Koleva, P Prugniel, and I Vauglin, 48:407–409. Les Ulis, France: EDP Sciences.
Chicago author-date (all authors)
Schroyen, Joeri, Sven De Rijcke, and Sander Valcke. 2011. “Flat Metallicity Profiles in Rotating Dwarf Galaxies.” In EAS Publications Series, ed. M Koleva, P Prugniel, and I Vauglin, 48:407–409. Les Ulis, France: EDP Sciences.
Vancouver
1.
Schroyen J, De Rijcke S, Valcke S. Flat metallicity profiles in rotating dwarf galaxies. In: Koleva M, Prugniel P, Vauglin I, editors. EAS Publications Series. Les Ulis, France: EDP Sciences; 2011. p. 407–9.
IEEE
[1]
J. Schroyen, S. De Rijcke, and S. Valcke, “Flat metallicity profiles in rotating dwarf galaxies,” in EAS Publications Series, Lyon, France, 2011, vol. 48, pp. 407–409.
@inproceedings{2944794,
  abstract     = {Dwarf irregulars (dlrr) and flat, rotating dwarf ellipticals (dE) generally possess flat metallicity profiles while round dEs show strong metallicity gradients (Koleva et al. 2009). Unlike dEs, dlrrs also exhibit ongoing star formation (SF) (Dolphin et al. 2005), in most cases compatible with a continuous star formation history (SFH). We show results based on a large suite of Nbody-SPH simulations of flat dwarf galaxies, both rotating and non-rotating, performed with a modified version of GADGET2. They have a range of masses, flattenings and rotations speeds and are based on the spherical models of (Valcke et al. 2008). Specifically, we want to see if it is possible to reproduce these characteristics in isolated DG models. These simulations show that using rotation to flatten a dwarf galaxy is particularly efficient in turning a so-called "breathing" SFH (Valcke et al. 2008) into a more continuous SFH, and in producing flat metallicity profiles. Non-rotating dEs in a flattened dark-matter halo are not able to reproduce these characteristics. Thus, it appears that rotation is key to reproducing the observed characteristics. Rotation causes a "centrifugal barrier" which slows down the infall of gas, so that the low-level star formation is not centrally concentrated but occurs galaxy-wide, and in this way also prevents large-scale oscillations in the SFR. This mechanism of smearing out the star formation in time and space proves to be the principal reason for the flat metallicity profiles, instead of the often referred to "fountain mechanism" (De Young & Heckman 1994; Barazza & Binggeli 2002; Mac Low & Ferrara 1999; Ferrara & Tolstoy 2000). We therefore propose a "centrifugal barrier mechanism" which is able to explain the observations.},
  author       = {Schroyen, Joeri and De Rijcke, Sven and Valcke, Sander},
  booktitle    = {EAS Publications Series},
  editor       = {Koleva, M and Prugniel, P and Vauglin, I},
  isbn         = {9782759806621},
  issn         = {1633-4760},
  keywords     = {dark matter,star formation,galaxies,ELLIPTIC GALAXIES,EVOLUTION},
  language     = {eng},
  location     = {Lyon, France},
  pages        = {407--409},
  publisher    = {EDP Sciences},
  title        = {Flat metallicity profiles in rotating dwarf galaxies},
  url          = {http://dx.doi.org/10.1051/eas/1148089},
  volume       = {48},
  year         = {2011},
}

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