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Our CMB Motion: The Local Void influence Voids Devoid of Dwarfs: Cosmology or Gastrophysics? Brent Tully Institute for Astronomy University of Hawaii.

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Presentation on theme: "Our CMB Motion: The Local Void influence Voids Devoid of Dwarfs: Cosmology or Gastrophysics? Brent Tully Institute for Astronomy University of Hawaii."— Presentation transcript:

1 Our CMB Motion: The Local Void influence Voids Devoid of Dwarfs: Cosmology or Gastrophysics? Brent Tully Institute for Astronomy University of Hawaii

2 Fact 1: Gastrophysics must be important because the faint end of the luminosity function of galaxies depends on environment More dynamically evolved regions have steeper faint-end luminosity functions

3 Fact 2: The Dwarfs in Dynamically Evolved Regions are Overwhelmingly dE N5353/4 Group N5846 Group Local Group radius velocity

4 Fact 2: The Dwarfs in Dynamically Evolved Regions are Overwhelmingly dE Show me a concentration of dE galaxies and I’ll show you a place with large M/L N5353/4 Group N5846 Group Local Group radius velocity

5 Fact 3: Groups of Dwarfs - Evidence for Dark Halos All-sky census of dwarf galaxies and follow up observations with HST/ACS:  most dwarfs are in groups  most of the mass in small groups is invisible  gastrophysics inhibits the collection of gas and star formation in low mass halos or low density regions

6 Fact 4: The Local Void - a void extending 60 Mpc begins at the edge of the Local Group HI Parkes All Sky Survey Time Allocation Committees could have inferred the existence of the Local Void

7 hundreds of 5% distances within 6 Mpc marginal at 5 Mpc OK at 8 Mpc good at 3 Mpc

8 Fact 5: we are traveling with the Local Filament as a unit co-moving motion of the Local Group w.r.t. 159 galaxies at 1.1 < d < 7 Mpc is 9 km/s negligible!! velocity dispersion about the local expansion of groups and galaxies outside of groups is ~40 km/s within the Local Filament (Karachentsev et al. 2003, AA, 398, 479) cold flow!! green/yellow V pec ~0 red V pec > +100 blue V pec < -100

9 Where is the Local Filament going?

10 vector decompositions 1 Assume component toward Virgo Cluster: ~200 km/s => l = sgl = b = 74.5 sgb = -2.3 Subtract from Local Supercluster vector: ~211 km/s => l = 213 sgl = 12 b = -3 sgb = -75 attributed primarily to evacuation of Local Void

11 what does nothing look like? SGXSGY SGZ

12 A galaxy in the void The lonely dwarf galaxy ESO = KK246 at 9 Mpc within the Local Void has a peculiar velocity toward us of -216 km/s Our peculiar motion in the Local Supercluster of 298 km/s is almost in the same direction, so the peculiar motion out of the void of ESO = KK246 is at least 500 km/s with respect to the Local Supercluster TRGB HI KK246 M B =-14

13 Bulk Peculiar Velocities Virgo Leo Spur

14 local velocity anomaly 56 o 45 o 36 o 7.8 Mpc 8.9 Mpc 9.5 Mpc -400 km/s -540 km/s -285 km/s -260 km/s -510 km/s -260 km/s local filament Leo spur ~6 Mpc Local Void UGC 3974 D NGC 2903 milky way 211 km/s

15 vector decompositions 2 Assume component toward Virgo Cluster: ~200 km/s => l = sgl = b = 74.5 sgb = -2.3 Subtract from Local Supercluster vector: ~211 km/s => l = 213 sgl = 12 b = -3 sgb = -75 attributed primarily to evacuation of Local Void CMB motion Local Group frame: 619 km/s  l = b = 28.7  sgl = sgb= Subtract Local Supercluster vector leaves large-scale structure component: ~446 km/s  l = 300 b = 15  sgl = 163 sgb = -15 Attributed to structure on scales > 3,000 km/s

16 (again) Where is the Local Filament going? ~200 km/s ~211 km/s ~446 km/s attractors on large scales Kocevski & Ebeling 2006, ApJ, 645, 1043

17 Conclusio ns: 1.The ratio of dwarf to giant galaxies is highest in high density, dynamically evolved environments. In the standard hierarchical clustering paradigm, the ratio of low to high halo mass is higher in low density, dynamically unevolved regions. Either the paradigm is wrong or gas & stars are preferentially excluded from low mass halos in low density regions. 2.The evident existence of groups of dwarfs with extreme M/L suggest that gas & stars are excluded in these locals. It must be considered likely that the paucity of dwarfs in voids is due to the inability of halos to collect or retain gas in those environments.

18 Conclusio ns: 1.The ratio of dwarf to giant galaxies is highest in high density, dynamically evolved environments. In the standard hierarchical clustering paradigm, the ratio of low to high halo mass is higher in low density, dynamically unevolved regions. Either the paradigm is wrong or gas & stars are preferentially excluded from low mass halos in low density regions. 2.The evident existence of groups of dwarfs with extreme M/L suggest that gas & stars are excluded in these locals. It must be considered likely that the paucity of dwarfs in voids is due to the inability of halos to collect or retain gas in those environments. 3.The Local Filament within 7 Mpc is moving as a unit with low internal dispersion. The bulk motion of the filament is decomposed cleanly into 3 quasi-orthogonal components: a motion of ~200 km/s away from the Local Void, a motion of ~200 km/s toward the Virgo Cluster, and a motion of ~450 km/s toward clustering on large scales in the direction of Centaurus. 4.While we are moving toward -SGZ, the adjacent filament south of the supergalactic equator called Leo Spur has a bulk peculiar motion toward +SGZ and consequently is converging with our filament (in co-moving coordinates). 5.The lonely dwarf galaxy ESO lies 9 Mpc away, 8 Mpc deep into the Local Void. The galaxy appears to be a normal dIrr, with HI and leisurely ongoing star formation. The galaxy has a LARGE peculiar velocity toward the boundary of the void of over 500 km/s.


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