Extremely Large Telescope

Abstract:

We report 0.5"x0.9" resolution, interferometric observations of the 1.3 mm CO J=2-1 line in the infrared luminous galactic merger NGC 6240. About half of the CO flux is concentrated in a rotating but highly turbulent, thick disk structure centered between the two radio and near-infrared nuclei. A number of gas features connect this ~500 pc diameter central disk to larger scales. Throughout this region the molecular gas has local velocity widths which exceed 300 km/s FWHM and even reach FWZP line widths of 1000 km/s in a number of directions. The mass of the central gas concentration constitutes a significant fraction of the dynamical mass, M_gas(R<470 pc) ~ 2-4x10^9 M_o ~ 0.3-0.7 M_dyn. We conclude that NGC 6240 is in an earlier merging stage than the prototypical ultraluminous galaxy, Arp 220. The interstellar gas in NGC 6240 is in the process of settling between the two progenitor stellar nuclei, is dissipating rapidly and will likely form a central thin disk. In the next merger stage, NGC 6240 may well experience a major starburst like that observed in Arp 220.

Abstract:

We have obtained high-resolution UV images with the Hubble Space Telescope/Wide-Field Planetary Camera 2 of the central region of the dwarf elliptical galaxy NGC 205. Our images reveal that many of the hot UV stars previously detected and studied from the ground are actually multiple systems, open clusters, and star associations. We have performed photometry of two such clusters, and we find that our data are consistent with stellar ages of 50 and 100 Myr, respectively. From the number of massive stars in NGC 205, we estimate that the star formation episode in this galaxy has turned ∼1000 M⊙ of gas into stars over the last 100 Myr.

Abstract:

We report first results from the Streaming Motions of Abell Clusters (SMAC) project, an all-sky Fundamental Plane survey of 699 early-type galaxies in 56 clusters between ∼3000 and ∼14,000 km s-1. For this sample, with a median distance of ∼8000 km s-1, we find a bulk flow of amplitude 630 ± 200 km s-1 toward l = 260 ± 15°, b = -1 ± 12° with respect to the cosmic microwave background. The flow is robust against the effects of individual clusters and data subsets, the choice of Galactic extinction maps, Malmquist bias, and stellar population effects. The direction of the SMAC flow is ∼90° away from the flow found by Lauer & Postman, but it is in good agreement with the gravity dipole predicted from the distribution of X-ray-luminous clusters. Our detection of a high-amplitude coherent flow on such a large scale argues for excess mass density fluctuation power at wavelengths λ ≳ 60 h-1 Mpc, relative to the predictions of currently popular cosmological models.