Hubble Space Telescope images of submillimeter sources: large, irregular galaxies at high redshift

We present new Hubble Space Telescope STIS, high-resolution optical imaging of a sample of 13 submillimeter (submm) luminous galaxies, for which the optical emission has been pinpointed either through radio-1.4 GHz or millimeter interferometry. We find a predominance of irregular and complex morphologies in the sample, suggesting that mergers are likely common for submm galaxies. The component separation in these objects are on average a factor two larger than local galaxies with similarly high bolometric luminosities. The sizes and star formation rates of the submm galaxies are consistent with the maximal star formation rate densities of 20 Msun kpc^{-2} in local starburst galaxies (Lehnert & Heckman 1996). We derive quantitative morphological information for the optical galaxies hosting the submm emission; total and isophotal magnitudes, Petrosian radius, effective radius, concentration, aspect ratio, surface brightness, and asymmetry. We compare these morphological indices with those of other galaxies lying within the same STIS images. Most strikingly, we find ~70% of the submm galaxies to be extraordinarily large and elongated relative to the field population, regardless of optical magnitude. Comparison of the submm galaxy morphologies with those of optically selected galaxies at z~2-3 reveal the submm galaxies to be a morphologically distinct population, with generally larger sizes, higher concentrations and more prevalent major-merger configurations.Comment: 16 pages, 6 figures, scheduled for ApJ, v599, Dec10, 2003. Minor edits. For version with higher resolution figures, see http://www.submm.caltech.edu/~schapman/ms_v3.ps.g

Accurate long-range coefficients for two excited like isotope He atoms: He(21P2 ^1P)--He(21P2 ^1P), He(21P2 ^1P)--He(23P2 ^3P), and He(23P2 ^3P)--He(23P2 ^3P)

A general formalism is used to express the long-range potential energies in inverse powers of the separation distance between two like atomic or molecular systems with $P$ symmetries. The long-range molecular interaction coefficients are calculated for the molecular symmetries $\Delta$, $\Pi$, and $\Sigma$, arising from the following interactions: He($2 ^1P$)--He($2 ^1P$), He($2 ^1P$)--He($2 ^3P$), and He($2 ^3P$)--He($2 ^3P$). The electric quadrupole-quadrupole term, $C_{5}$, the van der Waals (dispersion) term $C_{6}$, and higher-order terms, $C_{8}$, and $C_{10}$, are calculated \textit{ab initio} using accurate variational wave functions in Hylleraas coordinates with finite nuclear mass effects. A comparison is made with previously published results where available

Synthesis and Activity of Six-Membered Cyclic Alkyl Amino Carbene–Ruthenium Olefin Metathesis Catalysts

Ru–cyclic alkyl amino carbene (Ru–CAAC) olefin metathesis catalysts perform extraordinarily in metathesis macrocyclization and ethenolysis, but previous studies have been limited to the use of five-membered CAAC (CAAC-5) ligands. In this work, we synthesized a different group of ruthenium catalysts with more σ-donating and π-accepting six-membered CAAC (CAAC-6) ligands, and their metathesis activity was probed through initiation studies, ring-closing metathesis (RCM), cross-metathesis, and ethenolysis. These catalysts display higher initiation rates than analogous Ru–CAAC-5 complexes but demonstrate lower activity in RCM and ethenolysis