CONSTRAINING GALACTIC INFALL WITH DEUTERIUM OBSERVATIONS

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Tijana Prodanovi, University of Novi Sad Brian D. Fields, University of Illinois at Urbana Champaign. CONSTRAINING GALACTIC INFALL WITH DEUTERIUM OBSERVATIONS. Only created in Big Bang (Epstein et al. 1976, Prodanovi & Fields 2003 ) All other processes destroy it - PowerPoint PPT Presentation

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  • Tijana Prodanovi, University of Novi SadBrian D. Fields, University of Illinois at Urbana ChampaignTijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Only created in Big Bang (Epstein et al. 1976, Prodanovi & Fields 2003)All other processes destroy itMonotonic decline from high to low zDeuterium a powerful tool in cosmology!Cosmic baryometer! BBN success storyMeasure of how much gas was processed in stars!

    Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Large (factor of 3!) variations of D abundance in local ISM over different lines of sight!Both high and low D abundances foundResolution to the problem? (Linsky at al. 2006)Deuterium severely depleted onto dust!Measure lower bound on the true DTrue ISM D abundance

    True ISM D = 85% of PRIMORDIAL!?Almost NO GASS was PROCESSED in stars!? recall: stars completely destroy D!

    Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Deuterium must be replenished somehowINFALL/ACCRETION OF PRISTINE GAS!Eg. High-velocity cloudsfalling on our Galaxysome with metallicity ~10% Solarlittle or no dustTijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Increases ISM D abundanceIncreases gas content of the GalaxyDilutes metal content of the Galaxy

    Turns out:Deuterium and Galactic gas fraction observations powerful constraint of the infall rateTijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Build a keep it simple modelInfall and NO outflowInfall rate proportional to star-formation rate

    Define gas mass fraction

    Specify return fraction R fraction of initiall stellar mass that is returned to ISM (follows from Initiall mass function); eg. from Salpeter IMF

    Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • D vs. gas fractionShaded = observationsSolution must satisfy both

    Allowed infall rate

    Almost balances out star-formation!

    Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • At late times D and gas fraction approach minimum valuesLimiting curves above which no solutions for range of return fractionsAllowed onlyModern IMFs demand Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Local ISM D severely depleted onto dustLocal ISM D abundance could be close to primordialThen Local D and gas fraction observations demand large infall rate , close to star-formation rateConsistent with hierarchical assembly of galaxies by accretionModern IMFs demand return fraction R~0.4 , but only marginally consistent with our resultsTijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*Prodanovic & Fields, Journal of Cosmology and Astroparticle Physics, Issue 09, pp. 003(2008)

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*Where D is the deuterium mass fraction defined as:Taking we get:which we can express in terms of the present gas mass fraction by using:

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*Approximate:Then, define return fraction for each progenitor mass as:To find a global return fraction must specify the IMF:For mass rangesand Salpeter IMFwe find return fractionModern IMFs are flatter in the high-mass regime more high-mass stars more ejecta larger return fractions

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*For large infall where For small infall where

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*Freshly synthesized metalsSN metal yieldPresent reasonable estimatesconsistent with large or no infallsince all curves converge.

    XV National Conference of Astronomers of Serbia, October 4th 2008

  • Tijana ProdanoviXV National Conference of Astronomers of Serbia, October 4th 2008*Cyburt et al. (2004)

    XV National Conference of Astronomers of Serbia, October 4th 2008

    kflajsfljThis is a false-color image of the star AE Aurigae (bright source of light slightly off center of image) embedded in a region of space containing smoke-like filaments of carbon-rich dust grains, a common phenomenon. Such dust might be hiding deuterium, an isotope of hydrogen, and stymieing astronomers' efforts to study star and galaxy formation. The FUSE satellite has surveyed the local deuterium concentration in the galaxy and found far more than expected. Because deuterium is a tracer of star and galaxy evolution, this discovery could radically alter theories about how stars and galaxy form.kflajsflj**kflajsfljReasonable stellar processing: ISM D = 55% of primordial

    kflajsflj**kflajsfljM51: Cosmic Whirlpool Credit: S. Beckwith (STScI) Hubble Heritage Team, (STScI/AURA), ESA, NASA Explanation: Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you might find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (right), NGC 5195. The pair are about 31 million light-years distant and officially lie within the boundaries of the small constellation Canes Venatici. Though M51 looks faint and fuzzy in small, earthbound telescopes, this sharpest ever picture of M51 was made in January 2005 with the Advanced Camera for Surveys on board the Hubble Space Telescope.

    kflajsflj**kflajsfljAt late times: for a large infall deuterium spending through stellar processing and deuterium replenishing through infall will reach some equilibrium constant value that will depend on alpha and R only, but same will be for a small infall since the all the gas will eventually be exhausted except for some small fraction continuously infalling; similarly for gas mass fraction for large infall reaches some equilibrium, while for small infall there is no minimum value since gas fraction will go to zero. kflajsflj**kflajsflj*kflajsflj*kflajsflj*kflajsflj*

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