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Dwarf Galaxies in Group Environments Marla Geha Carnegie Observatories (OCIW)

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Presentation on theme: "Dwarf Galaxies in Group Environments Marla Geha Carnegie Observatories (OCIW)"— Presentation transcript:

1 Dwarf Galaxies in Group Environments Marla Geha Carnegie Observatories (OCIW)

2 Dwarf Galaxies in Group Environments. Mr > -18 dE, dIrr, dSph Bullock et al. (2000) Few studies of dwarf population in groups similar to Local Group.

3 SDSS Group Catalog Group catalog by A. Berlind. Galaxy members down to M r <

4 SDSS Group Catalog Group catalog by A. Berlind. Galaxy members down to M r < mr =19.5

5 Spatial Distribution of Nearby SDSS Groups Groups with 4 to 10 members Mr < between 0.01< z < 0.03.

6 The Sloan and Las Campanas Kinematics and Environment Redshift Survey Goal: Establish group membership for galaxies down to Mr < -15 in large sample of low density groups. M. Blanton, A. Berlind (NYU) SDSS r-band image: ~45’ = 5000km/s

7 The Sloan and Las Campanas Kinematics and Environment Redshift Survey Goal: Establish group membership for galaxies down to Mr < -15 in large sample of low density groups. M. Blanton, A. Berlind (NYU) SDSS r-band image: ~45’ = 5000km/s

8 Local Group Expect 7 additional dwarfs in ~1 sq deg for 5000 km/s 5 galaxies 12 galaxies Groups with 4 to 10 members Mr < between 0.01< z < 0.03.

9 Preliminary Results (g - r) Multislit spectroscopy Las Campanas 100inch WFCCD (FOV = 25’x18’) Target selection mr = 19.5 (g-r) < 1.0 February groups observed 56 dwarf members found ~10% observing efficiency Color distribution Mr

10 Stay tuned for more results from SLaCKERS...

11 A Dwarf Galaxy in the Local Group: NGC 205 NGC 205 is a dE satellite of M31. Provides detailed view of a disrupting satellite. Does the accretion of dwarf galaxies contribute significantly to the build-up of galactic halos? Constrain interaction via kinematics of individual stars.

12 Evidence for Interactions McConnachie et al. (2004) Ferguson et al. (2002)

13 Evidence for Interactions McConnachie et al. (2004) Ferguson et al. (2002)

14 NGC 205: Observations Integrated light spectra cannont probe beyond effective radius Targeted individual RGB star. Accurate radial velocities for 723 stars in NGC 205. Keck/DEIMOS Multislit Spectroscopy P. Guhathakuta, G. Laughlin (UCSC)

15 Keck/DEIMOS Observations

16 NGC 205: Major-axis Velocity Profile Inner rotation = 15 km s -1

17 NGC 205: Major-axis Velocity Profile Inner rotation = 15 km s -1 Velocity turns over beyond 2.5 r_eff.

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19 Orbital Simulations Restricted three-body models Mass ratio 20:1 Fit to photometry and velocity data Bound orbits only Genetic algorithm

20 Orbital Simulations

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23 Preliminary Results McConnachie et al. loop HI cloud

24 Summary NGC Confirm inner rotation velocity of ~15 km/s. -- Tidally disturbed region has velocities opposite that of main body. -- Constraints on orbit of NGC 205. SLaCKERS -- Survey of dwarf galaxy population (Mv < -15) in low density SDSS groups.


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