Modelling the Spectral Energy Distribution of Compact Luminous Infrared Galaxies: Constraints from High Frequency Radio Data

We have performed 23 GHz VLA observations of 7 compact, luminous infrared galaxies, selected to have evidence of starburst activity. New and published multi-frequency data are combined to obtain the spectral energy distributions of all 7 galaxies from the near-infrared to the radio (at 1.4 GHz). These SEDs are compared with new models, for dust enshrouded galaxies, which account for both starburst and AGN components. In all 7 galaxies the starburst provides the dominant contribution to the infrared luminosity; in 4 sources no contribution from an AGN is required. Although AGN may contribute up to 50 percent of the total far--infrared emission, the starbursts always dominate in the radio. The SEDs of most of our sources are best fit with a very high optical depth of (>=50) at 1 micron. The scatter in the far-infrared/radio correlation, found among luminous IRAS sources, is due mainly to the different evolutionary status of their starburst components. The short time-scale of the star formation process amplifies the delay between the far-infrared and radio emission. This becomes more evident at low radio frequencies (below about 1 GHz) where synchrotron radiation is the dominant process. In the far-infrared (at wavelengths shorter than 100 micron) an additional source of scatter is provided by AGN, where present. AGN may be detected in the near-infrared by the absence of the knee, typical of stellar photospheres. However, near-infrared data alone cannot constrain the level at which AGN contribute because the interpretation of their observed properties, in this wave-band, depends strongly on model parameters.Comment: 14 pages, accepted for publication in Astronomy and Astrophysic

II Zwicky 23 and Family

II Zwicky 23 (UGC 3179) is a luminous, nearby compact narrow emission line starburst galaxy with blue optical colors and strong emission lines. We present a photometric and morphological study of II Zw 23 and its interacting companions using data obtained with the WIYN 3.5-m telescope in Kitt Peak, Arizona. II Zwicky 23 has a highly disturbed outer structure with long trails of debris that may be feeding tidal dwarfs. Its central regions appear disky, a structure that is consistent with the overall rotation pattern observed in the H-alpha velocity field measured from Densepak observations obtained with WIYN. We discuss the structure of II Zwicky 23 and its set of companions and possible scenarios of debris formation in this system.Comment: 5 pages, 2 figures. To appear in the proceedings of ESO Astrophysics Symposia: "Groups of Galaxies in the Nearby Universe", eds. I. Saviane, V. Ivanov, J. Burissova (Springer

The City: Art and the Urban Environment

The City: Art and the Urban Environment is the fifth annual exhibition curated by students enrolled in the Art History Methods class. This exhibition draws on the students’ newly developed expertise in art-historical methodologies and provides an opportunity for sustained research and an engaged curatorial experience. Working with a selection of paintings, prints, and photographs, students Angelique Acevedo ’19, Sidney Caccioppoli ’21, Abigail Coakley ’20, Chris Condon ’18, Alyssa DiMaria ’19, Carolyn Hauk ’21, Lucas Kiesel ’20, Noa Leibson ’20, Erin O’Brien ’19, Elise Quick ’21, Sara Rinehart ’19, and Emily Roush ’21 carefully consider depictions of the urban environment in relation to significant social, economic, artistic, and aesthetic developments. [excerpt]https://cupola.gettysburg.edu/artcatalogs/1029/thumbnail.jp

Catalog of Radio Galaxies with z>0.3. I:Construction of the Sample

The procedure of the construction of a sample of distant ($z>0.3$) radio galaxies using NED, SDSS, and CATS databases for further application in statistical tests is described. The sample is assumed to be cleaned from objects with quasar properties. Primary statistical analysis of the list is performed and the regression dependence of the spectral index on redshift is found.Comment: 9 pages, 6 figures, 2 table