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What’s New with Peculiar Velocities?

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Presentation on theme: "What’s New with Peculiar Velocities?"— Presentation transcript:

1 What’s New with Peculiar Velocities?
hundreds of 5% distances within 6 Mpc galaxies gather in groups; few are isolated modest group masses; don’t account for much of mean matter density small dispersion in velocities on ~5 Mpc scales dynamically evolved clusters with large M/L significant streaming - local velocity anomaly suggests the existence of considerable mass associated with filaments but outside of groups

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

3 good distances 2 a group of dwarf galaxies at 3 Mpc

4 good distances 3 a group at almost 8 Mpc with a large peculiar velocity VLG = 180 km/s Vpec= -380 km/s

5 good distances 4 all-sky inventory off POSS for dwarfs by
Karachentseva and Karachentsev ; HI follow-up provides velocities about 200 of ~400 suspected to lie within ~7 Mpc now have good distances if you are ever on the HST TAC, give us time to do more!

6 galaxies gather in groups; few are isolated

7 galaxies gather in groups
2-point correlation signal dominated by groups like Local Group only dwarf groups

8 the local group quasi-virialized infall MW M31 31

9 galaxies at 1.1 - 3.2 Mpc |b|>30o [66 Mpc3]
beyond Local Group 14+7 N U N U N U UA 14+8 U U U U dregs U U KKH KK KKR Mpc kpc 14+12 N Sex B Sex A Antlia KKH60 ? ? 2x1011 M in 0.4 Mpc3 14+13 N N E E E IC 9x1011 M in 0.3 Mpc3 

10 modest group masses Omegam ~0.27
The mass in nearby groups of spirals is well below the level needed to explain the cosmic mean density

11 small dispersion in velocities on ~5 Mpc scales

12 dynamically evolved environments with large Vpec
V=1779 km/s V= 558 km/s

13 significant streaming - the local velocity anomaly
Milky Way plane of local filament -460 km/s -380 km/s 14+19 group VLG=182 km/s

14 Numerical Action Models
Best models: only ~1/3 of mass distributed like galaxies considerable mass smoothly distributed on 5-10 Mpc scale

15 low velocity dispersion locally [~30 km/s]
modest M/L in groups of spiral galaxies [< 100] large streaming motions between filaments [several x 100 km/s] global M/L assignments in NAM models in reasonable agreement with concordance model [~200] conclusion: Suggests the existence of considerable mass associated with filaments but outside of groups


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