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Metal Mixing in Blue LSB Galaxies: Age Measurement Techniques

Discover how to measure the ages of blue LSB galaxies through metal mixing studies. Learn about relevant research and conclusions from leading astronomers in the field, including galaxy formation, chemical inhomogeneity, and dynamic modeling. Explore the impact of shock frequency, star formation scenarios, and oxygen abundance distribution on age determination in LSB galaxies.

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Metal Mixing in Blue LSB Galaxies: Age Measurement Techniques

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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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