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
hundreds of 5% distances within
6 Mpc
marginal at 5 Mpc
OK at 8 Mpc
good at 3 Mpc
good distances 2
a group of dwarf galaxies at 3 Mpc
good distances 3
a group at almost 8 Mpc with a large peculiar velocity
VLG = 180 km/sVpec= -380 km/s
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!
galaxies gather in groups; few are isolated
galaxies gather in groups
2-point correlation
signal dominated by groups like Local Group
only dwarf groups
the local group
MWM31
31
quasi-virialized infall
galaxies at 1.1 - 3.2 Mpc |b|>30o [66 Mpc3]
beyond Local Group Mpc kpc14+12 N3109 1.33 -15.5 310 Sex B 1.39 -14.0 450 Sex A 1.40 -13.8 210 Antlia 1.25 -9.3 350 KKH60 ? -7.8 ?
2x1011 M in 0.4 Mpc3
14+13 N 55 2.19 -17.9 190 N 300 1.87 -17.5 320 E407-18 2.14 -12.9 400 E410-05 1.92 -11.6 200 E294-10 2.00 -11.0 200 ----------------------- IC5152 2.07 -15.6 820
9x1011 M in 0.3 Mpc3
14+7 N4214 2.83 -17.1 U7577 2.55 -14.2 N4163 2.96 -13.8 U6817 2.56 -13.5 N3741 3.13 -13.2 U8508 2.59 -13.0 UA276 2.84 -11.7
14+8 U9240 2.79 -14.2 460 U8760 3.24 -13.2 210 U8651 3.02 -12.9 180 U8833 3.20 -12.4 260
dregs U9128 2.24 -12.5 300 U8091 2.10 -12.0 490 KKH86 2.52 -10.3 670 KK230 1.90 -8.6 700 KKR25 1.85
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
small dispersion in velocities on ~5 Mpc scales
dynamically evolved environments with large Vpec
V=1779 km/s
V= 558 km/s
significant streaming - the local velocity anomaly
Milky Way
14+19 groupVLG=182 km/s
-380 km/s
-460 km/s
plane of local filament
Numerical Action Models
Best models:
• only ~1/3 of mass distributed like galaxies
• considerable mass smoothly distributed on 5-10 Mpc scale
conclusion:
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]
Suggests the existence of considerable mass associated with filaments but outside of groups