Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott...
-
Upload
rosanna-powers -
Category
Documents
-
view
218 -
download
0
description
Transcript of Alan McConnachie Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott...
Alan McConnachie
Mike Irwin, Annette Ferguson, Nial Tanvir, Rodrigo Ibata, Geraint Lewis, Scott Chapman, Avon Huxor
A Bird’s Eye View of M31 and its
Satellite Galaxies
IDM2004
The INT WFS of M31:
Ibata et al. 2001Ferguson et al. 2002
Irwin et al. 2004
Status as of July 2001(58 pointings)
Currently 165 pointings+ M33 (21 pointings) + total of 15 other dwarf galaxies
Blue RGB Red RGB12
5 kp
c
95 kpcFaintest features:
Faintest features have
Extent of the Stream:CFH12K Mosaic
McConnachie et al. 2003
Progress so far...
Ibata et al. 2004
radial velocities for ~15 000 stars in 34 distinct fields
concentrated on known substructure, general halo, and outer disk fields
RVs accurate to ~5km/s
McConnachie et al. 2004aKeck/DEIMOS radial velocity survey of M31
And VIIIIbata et al. 2004
First DIRECT measurement of the gravitational potential of a giant galaxy out to ~125 kpc:
Best fitting orbits:
Ibata et al. 2004
The Satellite Galaxies of Andromeda:
McConnachie et al. 2004b,c
Andromeda I & II
TRGB = 20.40 TRGB = 20.13
An M31 All-Sky View:(Aitoff equal-area projection)
An M31 All-Sky View:(Aitoff equal-area projection)
An M31 All-Sky View:
Preference for satellites to lie on near side of M31
The Line-of-Sight Probability Distribution Function
Why are the satellites lop-sided?
Why do they know about the Milky Way?
Are they tracing the underlying potential?
•Copious amounts of substructure: clue to formation history?
•First direct measure of dynamical mass of a galaxy over such a large distance range:
•Satellite distribution shows a strong anisotropy; tracers of underlying dark matter potential?
Summary: