Curriculum Vitae
Kim-Vy H. Tran, SNF Professor

Education:
1996 B.S. in Physics, U. of Arizona
1996 B.S. in Astronomy with Honors, U. of Arizona
2000 M.S. in Astronomy & Astrophysics, UC Santa Cruz
2002 Ph.D. in Astronomy & Astrophysics, UC Santa Cruz

Research History:
1996-2002 Research assistant, UC Santa Cruz
2002-2005 Postdoctoral researcher, ETH Zuerich
2005-2006 NSF AAPF fellow, Harvard-Smithsonian Center for Astrophysics
2005-2006 NOVA fellow, Leiden Observatory
2006-present SNF professor, University of Zuerich

Awards/Recognition:
2005 NSF Astronomy & Astrophysics Fellow
2005 NOVA Fellow
2006 SNF Faculty Fellowship

Teaching:
Spring 2007 Introduction to Modern Astrophysics
Fall 2007 Overview of Modern Astrophysics
Spring 2008 Introduction to Modern Astrophysics

Projects:

Stellar Assembly in SG1120, a Super-Galaxy Group at z=0.37:

SG1120 is a uniquely overdense region detected in the 130 sq. degree Las Campanas Deep Cluster Survey (Gonzalez et al. 2001) area. Deep follow-up Chandra imaging revealed six extended, X-ray luminous sources in the 16'x16' region (Fig. 1). Optical spectroscopy confirms that four of the extended X-ray sources correspond to groups at 0.35<z<0.37; we currently have 198 confirmed SG1120 members (Fig.2). A dynamical analysis shows that the groups at z~0.37 are likely gravitationally bound to each other and have a combined mass of 5e14 Msun, i.e. they will merge and form a cluster comparable in mass to Coma (Gonzalez et al. 2005). Our multi-faceted observational campaign of SG1120 thus far includes an HST/ACS F814W mosaic (Fig. 3), wide-field ground-based BVRJKs imaging, Chandra imaging, and SST/MIPS 24 micron imaging.

xray-z
X-ray image from Chandra of the supergroup field; the image is 13'x13'. The supergroup is composed of four individual groups (0.35<z<0.37); there are also two background groups at z=0.48.

gracs

Galaxies in a supergroup at z=0.37. This composite image is generated by combining an HST/ACS mosaic with ground-based g'r' mosaics from Magellan. The individual galaxy groups that make up SG1120 have yet to merge, but 1) they have twice as many absorption line (passive) galaxies as the field (61% vs. 27%) and 2) the group galaxies show a trend in star formation activity with environment that is typical of galaxies in rich clusters. These results conclusively prove that the group environment plays an important role in developing the early-type galaxies that dominate the cluster population by z~0.


A Keck Spectroscopic Survey of MS 1054-03 (z=0.83): Forming the Red Sequence

Using a magnitude-limited, spectroscopic survey of the X-ray luminous galaxy cluster MS1054-03, we isolate 153 cluster galaxies and measure MS1054's redshift and velocity dispersion to be z=0.8307 and sigma_z=1156 km/s. The absorption-line, post-starburst (``E+A''), and emission-line galaxies respectively make up 63%, 15%, and 23% of the cluster population. With photometry from HST/ACS, we find that the absorption-line members define an exceptionally tight red sequence over a span of ~3.5 magnitudes in i775. The color scatter of MS1054's absorption-line population is approximately twice that of the ellipticals in Coma; this difference is consistent with passive evolution where most of the absorption-line members (>75%) formed by z~2, and all of them by z~1.2. For red members, we find a trend (>95% confidence) of weakening Hdelta absorption with redder colors that we conclude is due to age: in MS1054, the color scatter on the red sequence is driven by differences in mean stellar age of up to ~1.5 Gyr.

ms1054-cmd
Right: Color-magnitude (CM) diagrams for the cluster galaxies that fall on the ACS mosaic where members are separated in spectral types (top two panels) and Hubble types (bottom two panels); the solid line is the color-magnitude relation defined by the red, absorption-line members. Left: The difference in measured color and color predicted by the CM relation for the same galaxies; the dotted line is our division between red and blue members.

Publications

Academic Summary

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