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The Megamaser Cosmology Project (MCP) measures the Hubble Constant by determining geometric distances to circumnuclear 22 GHz H2O megamasers in galaxies at low redshift (z < 0.05) but well into the Hubble flow. In combination with the recent, exquisite observations of the Cosmic Microwave Background by WMAP and Planck, these measurements provide a direct test of the standard cosmological model and constrain the equation of state of dark energy. The MCP is a multi-year project that has recently completed observations and is currently working on final analysis. Based on distance measurements to the first four published megamasers in the sample, the MCP currently determines H0 = 69.3 ± 4.2 km s−1 Mpc−1. The project is finalizing analysis for five additional galaxies. When complete, we expect to achieve a ~4% measurement. Given the tension between the Planck prediction of H0 in the context of the standard cosmological model and astrophysical measurements based on standard candles, the MCP provides a critical and independent geometric measurement that does not rely on external calibrations or a distance ladder.
We present a search for OH maser emission in galaxies hosting H2O masers with the 100-m Effelsberg radio telescope and the Green Bank Telescope (GBT). This survey is aimed at investigating the apparent rarity and/or possible mutual exclusion of megamaser emission from OH and H2O in the same galaxy. Our study establishes new and better upper limits on the OH maser luminosity. Our work duplicates the number of H2O masers searched for OH emission. No new maser detections have been found. OH absorption, both in the 1667 and 1665 MHz transitions, is instead detected in two galaxies of the sample, IC342 and NGG5793.
Many accretion disks surrounding supermassive black holes in nearby AGN are observed to host 22 GHz water maser activity. We have analyzed single-dish 22 GHz spectra taken with the GBT to identify 32 such “Keplerian disk systems,” which we used to investigate maser excitation and explore the possibility of disk reverberation. Our results do not support a spiral shock model for population inversion in these disks, and we find that any reverberating signal propagating radially outwards from the AGN must constitute <10% of the total observed maser variability. Additionally, we have used ALMA to begin exploring the variety of sub-mm water megamasers that are also predicted, and in the case of the 321 GHz transition found, to be present in these accretion disks. By observing multiple masing transitions within a single system, we can better constrain the physical conditions (e.g., gas temperature and density) in the accretion disk.
The RadioAstron space-VLBI mission has successfully detected extragalactic H2O MegaMaser emission regions at very long Earth to space baselines ranging between 1.4 and 26.7 Earth Diameters (ED). The preliminary results for two galaxies, NGC 3079 and NGC 4258, at baselines longer than one ED indicate masering environments and excitation conditions in these galaxies that are distinctly different. Further observations of NGC 4258 at even longer baselines are expected to reveal more of the physics of individual emission regions.
We present the results of a survey of several tens of dense high mass star forming (HMSF) cores in three transitions of the SO molecule at 30 and 100 GHz with the 100-m Effelsberg and 20-m Onsala radio telescopes. The physical parameters of the cores are estimated from the line ratios and column densities. Relative abundances are derived as well.
Hitler's Machtergreifung, or seizure of power, on January 30, 1933, marked the end of the Weimar Republic and the beginning of the Third Reich, and German film scholarship has generally accepted this date as the break between Weimar and Nazi-era film as well. This collection of essays interrogates the continuities and discontinuities in German cinema before and after January 1933 and theirrelationship to the various crises of the years 1928 to 1936 in seven areas: politics, the economy, concepts of race and ethnicity, the making of cinema stars, genre cinema, film technologies and aesthetics, and German-international film relations. Focusing both on canonical and lesser-known works, the essays analyze a representative sample of films and genres from the period. This book will be ofinterest to scholars and students of Weimar and Third Reich cinema and of the sociopolitical, economic, racial, artistic, and technological spheres in both late Weimar and the early Third Reich, as well as to film scholars in general.
Contributors: Paul Flaig, Margrit Frölich, Barbara Hales, Anjeana Hans, Bastian Heinsohn, Brook Henkel, Kevin B. Johnson, Owen Lyons, Richard W. McCormick, Kalani Michell, Mihaela Petrescu, Christian Rogowski, Valerie Weinstein, Wilfried Wilms.
Barbara Hales is Associate Professor of History at the University of Houston-Clear Lake. MihaelaPetrescu is Visiting Lecturer at the University of Pittsburgh. Valerie Weinstein is Assistant Professor of Women's, Gender, and Sexuality Studies and German Studies at the University of Cincinnati.