Our CMB Motion: The Local Void influence Voids Devoid of Dwarfs: Cosmology or Gastrophysics

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Our CMB Motion The Local Void influenceVoids
Devoid of Dwarfs Cosmology or Gastrophysics?
Brent Tully Institute for Astronomy University
of Hawaii
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Fact 1 Gastrophysics must be importantbecause
the faint end of the luminosity function of
galaxies depends on environment
More dynamically evolved regions have steeper
faint-end luminosity functions
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Fact 2 The Dwarfs in Dynamically Evolved Regions
are Overwhelmingly dE
N5353/4 Group
Local Group
velocity
radius
N5846 Group
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Fact 2 The Dwarfs in Dynamically Evolved Regions
are Overwhelmingly dE
N5353/4 Group
Local Group
velocity
radius
N5846 Group
Show me a concentration of dE galaxies and Ill
show you a place with large M/L
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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

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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
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hundreds of 5 distances within 6 Mpc
good at 3 Mpc
marginal at 5 Mpc
OK at 8 Mpc
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Fact 5 we are traveling with the Local Filament
as a unit
green/yellow Vpec0 red Vpec gt 100 blue Vpec lt
-100

• co-moving motion of the
• Local Group w.r.t. 159 galaxies
• at 1.1 lt d lt 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!!

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Where is the Local Filament going?
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vector decompositions 1
Assume component toward Virgo Cluster 200
km/s gt l 282.9 sgl 102.7
b 74.5 sgb -2.3 Subtract from
Local Supercluster vector 211 km/s gt l
213 sgl 12 b
-3 sgb -75 attributed primarily to
evacuation of Local Void
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what does nothing look like?
SGZ
SGX
SGY
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A galaxy in the void
The lonely dwarf galaxy ESO461-36 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 ESO461-36 KK246 is at least 500
km/s with respect to the Local Supercluster
MB-14
TRGB
HI
KK246
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Bulk Peculiar Velocities
Virgo
Leo Spur
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local velocity anomaly
Local Void
milky way
local filament
36o
8.9 Mpc
45o
211 km/s
56o
6 Mpc
9.5 Mpc
7.8 Mpc
-285 km/s
-260 km/s
-260 km/s
NGC 2903
-400 km/s
-510 km/s
Leo spur
UGC 3974
-540 km/s
D634-03
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vector decompositions 2

• CMB motion
• Local Group frame 619 km/s
• l 275.2 b 28.7
• sgl 140.2 sgb -32.2
• 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 gt 3,000 km/s

Assume component toward Virgo Cluster 200
km/s gt l 282.9 sgl 102.7
b 74.5 sgb -2.3 Subtract from
Local Supercluster vector 211 km/s gt l
213 sgl 12 b
-3 sgb -75 attributed primarily to
evacuation of Local Void
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(again)Where is the Local Filament going?
200 km/s
446 km/s
attractors on large scales
211 km/s
Kocevski Ebeling 2006, ApJ, 645, 1043
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Conclusions

• 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.
• 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.

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Conclusions

• 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.
• 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.
• 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.
• 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).
• The lonely dwarf galaxy ESO 461-36 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.