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Mixing of metals in blue LSB galaxies ( or How one can measure their ages )

Mixing of metals in blue LSB galaxies ( or How one can measure their ages ). Yuri Shchekinov (Southern Federal U) Eduard Vorobyov (St. Marry U, S Fed U) Domink Bomans (AI RUB) Ralf-Jurgen Dettmar (AI RUB) Dmitry Bizyaev (New Mexico State U, Sternberg AI).

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Mixing of metals in blue LSB galaxies ( or How one can measure their ages )

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  1. Mixing of metals in blue LSB galaxies (or How one can measure their ages) Yuri Shchekinov(Southern Federal U) Eduard Vorobyov(St. Marry U, S Fed U) Domink Bomans(AI RUB) Ralf-Jurgen Dettmar(AI RUB) Dmitry Bizyaev(New Mexico State U, Sternberg AI) Nearby Dwarf Galaxies, SAO Nizhny Arkhyz, 14-19 September 2009

  2. LSBs vs hierarchical structure formation • colors • gas mass • metallicities LSBs may have formed recently!

  3. Aging Schombert etal 2001: HI content, V-I photometry  LSB dwarfs t≤5 Gyr Haberzettl etal 2005: Spectral energy distribution  t=2-5 Gyr Padoan etal 1997, Jimenez etal 1998: U-B, B-V, B-R, V-I photometry  t≥7-9 Gyr Zackrisson etal 2005: optical/NIR photometry + H-alpha EW  t=1-2 Gyr (though 10-14 Gyr equally well reproduce the data) Vorobyov , YuS, Bomans, Dettmar & Bizyaev 2009: aging through chemical inhomogeneity

  4. 2D hydrodynamic simulations: ∫ .. dz + chemistry (instantaneous recycling) + photometry + sporadic SF

  5. Mixing in the MW • Shock frequency Draine & Salpeter 1979

  6. Mixing in the MW • Numerical examplesAvillez & MacLow 2002 t=50 Myr t=126.6 Myr t=0

  7. Mixing in LSBs • Shock frequency with a 0.1 SFR Boissier etal 2008 t=126.6 Myr in the MW t=1.266 Gyr in LSB 

  8. SF in LSBs = 0.1 SF in MW • SNR filling factor assume linear proportionality

  9. Mixing in LSBs no mixing! unless differential rotation & spiral waves help

  10. Dynamical model of a LSB

  11. Dynamical model of a LSB de Blok 05 • V(R)

  12. Dynamical model of a LSB • Equations: 2D hydro+instantaneous recycling

  13. 4 if T < T = 10 K cr Δ t = 20 Myr SF Dynamical model of a LSB • SF scenario: sporadic SF Schmidt law SF sites randomly distributed through the disk

  14. cooling rate (erg cm3/s) T 2 4 10 10 Radiative gas

  15. cooling rate (erg cm3/s) T 2 4 10 10 Radiative gas

  16. Dynamical model of a LSB • SF scenario: sporadic SF

  17. H-alpha emission:sporadic SF ESO-LV 0280140 model Auld et al 2006

  18. H-alpha emission:sporadic SF ESO-LV 1040220 model Auld et al 2006

  19. H-alpha emission:sporadic SF ESO-LV 1450250 model Auld et al 2006

  20. Dynamical model of a LSB Metal mixing

  21. Dynamical model of a LSB Metal mixing

  22. Dynamical model of a LSB Metal mixing

  23. Radial distribution of oxygen no grad in Z  no SF threshold

  24. Radial distribution of oxygen ! Observations by de Block & van der Hulst 1998

  25. Oxygen abundance

  26. H-alpha EW

  27. Oxygen & H-alpha EW K S

  28. Conclusions Patchy distribution of metals (1-2 kpc) remains distinguishable (0.5-1.0 dex) on 1-2 Gyr The abundance fluctuation spectrum is age-dependent, though hardly resolved [O/H] vs Hα EW seems good for constraining the age provided a preliminary information of the IMF is available Combined [O/H] and Hα EW data constrain LSB ages between 7 and 13 Gyr

  29. Спасибо !

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