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
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 - PowerPoint PPT Presentation
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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 ?
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