Research

I am interested in using the satellite galalxies of the Milky Way to place constraints on properties of the Milky Way dark halo, and to understand the process of mass build-up in the Milky Way. In order to understand the present structure of the Galaxy and to map out its formation process, we need velocities. Currently, I am working on a project studying the systemic and internal motions of the Magellanic Clouds using high resolution data taken with the ACS, a new instrument on the Hubble Space Telescope. These motions are of fundamental importance since they probe the gravitational potential of the dark halo. The main stumbling block in the measurement of the proper motion of the Clouds so far has been the lack of a good background inertial reference frame. But we can now overcome this problem with a set of 54 quasars that were identified from their variability characteristics in the MACHO database (Geha et al. 2003).

The project described here will determine the systemic motions of the Magellanic Clouds with a precision that can be used to constrain theoretical models of the dark halo of the Milky Way.

Image from http://antwrp.gsfc.nasa.gov/

First epoch observations of 28 of the 54 quasars have already been taken. Go to this visit information site for a quick synopsis of the observations, or download the data at your leisure from the table below. For an explanation of all the file extensions go to this HST FAQ page.

Visit No.	Field/Priority	RA/DEC	Data
1	LMC/HIGH	054750-672802	Data
2	LMC/HIGH	044611-720509	Data
3	LMC/HIGH	051628-683702	Data
4	LMC/HIGH	051636-663436	Data
5	LMC/HIGH	051536-705401	Data
6	LMC/HIGH	060234-683041	Data
7	LMC/HIGH	051626-694819	Data
8	LMC/HIGH	053009-660701	Data
9	LMC/HIGH	050054-664401	Data
10	LMC/HIGH	051522-705806	Data
11	LMC/HIGH	045356-694035	Data
12	LMC/HIGH	054941-694415	Data
14	SMC/HIGH	005116-721651	Data
15	SMC/HIGH	005534-722834	Data
16	SMC/HIGH	010214-731626	Data
17	SMC/HIGH	003639-722742	Data
18	SMC/HIGH	011141-724947	Data
21	LMC/MEDIUM	052056-702452	Data
22	LMC/MEDIUM	052402-701108	Data
26	LMC/MEDIUM	050436-662417	Data
28	LMC/MEDIUM	050017-693216	Data
29	LMC/MEDIUM	053026-664855	Data
31	LMC/HIGH	053131-712947	Data
33	LMC/MEDIUM	045614-673910	Data
35	LMC/MEDIUM	053600-704128	Data
36	SMC/MEDIUM	010234-725422	Data
37	LMC/LOW	061509-661740	Data
38	LMC/LOW	055847-670744	Data