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Missing Baryons in the Local Group

Missing Baryons in the Local Group. Matthias Steinmetz Astrophysical Institute Potsdam. Overview. Simulating Disk Galaxies Spectroscopic Surveys of the MW Geneva-Copenhagen, SDSS, RAVE Mass estimates Using cosmological simulations for data interpretation

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Missing Baryons in the Local Group

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  1. Missing Baryons in the Local Group Matthias Steinmetz Astrophysical Institute Potsdam

  2. Overview • Simulating Disk Galaxies • Spectroscopic Surveys of the MW • Geneva-Copenhagen, SDSS, RAVE • Mass estimates • Using cosmological simulations for data interpretation • Do we have consistency between different mass estimates? Missing Baryons, Accretion and Feedback in Galaxies

  3. Morphologies: Stellar mass density 4 galaxies with no/little disk 4 galaxies with disks Missing Baryons, Accretion and Feedback in Galaxies Scannapieco et al 2009

  4. Kinematic disk/spheroid decomposition Disks (4) No Disk (1) The highest disk-to-total ratios we obtain with the kinematic decomposition areD/T ~ 0.2 Simulation of a scaled-down version of our galaxy Missing Baryons, Accretion and Feedback in Galaxies Small Disks (3) Rotating bulge (1)

  5. Disk evolution and disk survival Galaxies with no disks at z=0 Galaxies with disk at z=0 Simulation of a scaled-down version of our galaxy DISK-TO-TOTAL Missing Baryons, Accretion and Feedback in Galaxies redshift redshift Most galaxies have disks at higher redshift Scannapieco et al 2009

  6. Disk survival and Mergers Galaxies with no disks at z=0 Galaxies with disk at z=0 DISK-TO-TOTAL Missing Baryons, Accretion and Feedback in Galaxies redshift redshift Only one major merger: destroys the diskSmaller mergers: can destroy disks but not necessarily do so Scannapieco et al 2009

  7. Disk survival and Misalignment Galaxies with no disks at z=0 Galaxies with disk at z=0 DISK-TO-TOTAL Missing Baryons, Accretion and Feedback in Galaxies redshift redshift Disks are shrinked/destroyed when infalling COLD GAS is misaligned with pre-existing STELLAR DISK Scannapieco et al 2009

  8. Mass-weighted Luminosity-weighted Kinematic vs photometric decomposition The photometric decomposition predicts higher D/T than the kinematic one Missing Baryons, Accretion and Feedback in Galaxies Scannapieco et al 2009

  9. Compare SDSS stellar mass function with DM halo mass function M⊙ Missing Baryons, Accretion and Feedback in Galaxies Forero et al 2009 Guo et al 2009

  10. Dark Matter in the Milky Way Dark Mass within the Solar Circle Missing Baryons, Accretion and Feedback in Galaxies Dark mass constraint from Oort limit Constraint from universal baryon fraction Eke, Navarro & Steinmetz 2001 Halo Mass (Circular Velocity)

  11. Missing Baryons, Accretion and Feedback in Galaxies

  12. Missing Baryons, Accretion and Feedback in Galaxies

  13. The Escape Velocity of the Milky-Way 498 < vesc< 608 km/s For an adiabatically contracted NFW dark halo: M⊙ Missing Baryons, Accretion and Feedback in Galaxies Non contracted NFW dark halo: M⊙ Smith et al 2007

  14. Vcirc and Vesc from SDSS M⊙ M⊙ RAVE Missing Baryons, Accretion and Feedback in Galaxies Xue et al 2008

  15. v200≈0.5 vDisk Pro • Tully Fisher • DM in disks Con • Abundance of disk galaxies Missing Baryons, Accretion and Feedback in Galaxies Abadi et al 2005

  16. Estimating vvir via satellites Missing Baryons, Accretion and Feedback in Galaxies MW M31

  17. Mass of the MW dark matter halo Missing Baryons, Accretion and Feedback in Galaxies Abadi et al 2009

  18. Compare SDSS stellar mass function with DM halo mass function M⊙ Missing Baryons, Accretion and Feedback in Galaxies Forero et al 2009 Guo et al 2009

  19. Fraction of collapsed baryons Missing Baryons, Accretion and Feedback in Galaxies Guo et al 2009

  20. What does that mean for the MW as a typical LCDM galaxy? • Is there an inconsistency between stellar dynamics, timing arguments and statistics? • We need better galaxy formation models • M ≈ 2.5×1012 M⊙ • Only ~20% of halos suitable hosts • >75% of the baryons in the MW are unaccounted for • Disk size: access to the full angular momentum reservoir • M ≈ 1012 M⊙ • MW would rather untypical or over abundant • Local group timing argument Missing Baryons, Accretion and Feedback in Galaxies

  21. The local universe is not a representative part of the universe. The MW is situated in a region of relatively low density and with large nearby mass concentrations like Virgo, the local supercluster, Perseus Pisces and Coma Missing Baryons, Accretion and Feedback in Galaxies

  22. Missing Baryons, Accretion and Feedback in Galaxies

  23. Local Group alikes are pretty rare! • analysis of 90 Mpc box, constrained simulation • WMAP5 normalization • one excellent candidate • Virgo: • Mass: 1.2×1014 M⊙(more massive) • distance: 14.9 Mpc (19.0 Mpc ← NED) • Fornax: • mass: 4.2 ×1013 M⊙(7.0×1013 M⊙← ApJ 548, L139) • distance: 19.2 Mpc (17.6 Mpc ← NED) • Local group • mass: 3.0×1013M⊙(lower mass end) • MW/Andromeda distance: 690kpc (700kpc) Missing Baryons, Accretion and Feedback in Galaxies

  24. Missing Baryons, Accretion and Feedback in Galaxies

  25. CLUES Missing Baryons, Accretion and Feedback in Galaxies

  26. Missing Baryons, Accretion and Feedback in Galaxies

  27. What does that mean for the MW as a typical LCDM galaxy? • Is there an inconsistency between stellar dynamics, timing arguments and statistics? • We need better galaxy formation models • M ≈ 2.5×1012M⊙ • Only ~20% of halos suitable hosts • >75% of the baryons in the MW are unaccounted for • Disk size: access to the full angular momentum reservoir • M ≈ 1012M⊙ • MW would rather untypical or over abundant • Local group timing argument Missing Baryons, Accretion and Feedback in Galaxies

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