Comparison of 30 day integrations with and without interactive clouds

A cloud radiation interaction parameterization package has recently been incorporated into a global spectral General Circulation Model (GCM) used for extended range prediction studies at GFDL. The elements of this package are summarized. Analysis of the time mean radiative and dynamical responses suggests that cloud radiation interaction has a favorable impact, overall, on systematic errors. The possible relevance of this sensitivity study to FIRE is mentioned

Mean and Extreme Radio Properties of Quasars and the Origin of Radio Emission

We investigate the evolution of both the radio-loud fraction (RLF) and (using stacking analysis) the mean radio-loudness of quasars. We consider how these values evolve as a function of redshift and luminosity, black hole (BH) mass and accretion rate, and parameters related to the dominance of a wind in the broad emission line region. We match the FIRST source catalog to samples of luminous quasars (both spectroscopic and photometric), primarily from the Sloan Digital Sky Survey. After accounting for catastrophic errors in BH mass estimates at high-redshift, we find that both the RLF and the mean radio luminosity increase for increasing BH mass and decreasing accretion rate. Similarly both the RLF and mean radio loudness increase for quasars which are argued to have weaker radiation line driven wind components of the broad emission line region. In agreement with past work, we find that the RLF increases with increasing luminosity and decreasing redshift while the mean radio-loudness evolves in the exact opposite manner. This difference in behavior between the mean radio-loudness and the RLF in L-z may indicate selection effects that bias our understanding of the evolution of the RLF; deeper surveys in the optical and radio are needed to resolve this discrepancy. Finally, we argue that radio-loud (RL) and radio-quiet (RQ) quasars may be parallel sequences but where only RQ quasars at one extreme of the distribution are likely to become RL, possibly through slight differences in spin and/or merger history.Comment: 55 pages, 28 figures, accepted to A

The Auslander-Gorenstein property for Z-algebras

We provide a framework for part of the homological theory of Z-algebras and their generalizations, directed towards analogues of the Auslander-Gorenstein condition and the associated double Ext spectral sequence that are useful for enveloping algebras of Lie algebras and related rings. As an application, we prove the equidimensionality of the characteristic variety of an irreducible representation of the Z-algebra, and for related representations over quantum symplectic resolutions. In the special case of Cherednik algebras of type A, this answers a question raised by the authors.Comment: 31 page

Conference Summary: AGN Physics with the Sloan Digital Sky Survey

The ``AGN Physics with the Sloan Digital Sky Survey'' conference was held at Princeton University in July 2003 to bring together groups working inside and outside of the SDSS collaboration at radio through X-ray wavelengths to discuss the common goal of better understanding the physics of Active Galactic Nuclei (AGN). Although we still do not have a full understanding of AGN, much progress has been made in recent years. In this conference summary, we concentrate on those topics discussed at the meeting where we believe that there has been significant change or where there is a new standard of comparison, as well as on important new trends in AGN research.Comment: 4 pages, no figures; text now fully matches published versio

Determining dust temperatures and masses in the Herschel era: The importance of observations longward of 200 micron

Context. The properties of the dust grains (e.g., temperature and mass) can be derived from fitting far-IR SEDs (≥100 μm). Only with SPIRE on Herschel has it been possible to get high spatial resolution at 200 to 500 μm that is beyond the peak (~160 μm) of dust emission in most galaxies. Aims. We investigate the differences in the fitted dust temperatures and masses determined using only 200 μm data (new SPIRE observations) to determine how important having >200 μm data is for deriving these dust properties. Methods. We fit the 100 to 350 μm observations of the Large Magellanic Cloud (LMC) point-by-point with a model that consists of a single temperature and fixed emissivity law. The data used are existing observations at 100 and 160 μm (from IRAS and Spitzer) and new SPIRE observations of 1/4 of the LMC observed for the HERITAGE key project as part of the Herschel science demonstration phase. Results. The dust temperatures and masses computed using only 100 and 160 μm data can differ by up to 10% and 36%, respectively, from those that also include the SPIRE 250 & 350 μm data. We find that an emissivity law proportional to λ^(−1.5) minimizes the 100–350 μm fractional residuals. We find that the emission at 500 μm is ~10% higher than expected from extrapolating the fits made at shorter wavelengths. We find the fractional 500 μm excess is weakly anti-correlated with MIPS 24 μm flux and the total gas surface density. This argues against a flux calibration error as the origin of the 500 μm excess. Our results do not allow us to distinguish between a systematic variation in the wavelength dependent emissivity law or a population of very cold dust only detectable at λ ≥ 500 μm for the origin of the 500 μm excess

Are There Opportunities to Increase Social Security Progressivity Despite Underfunding?

Reviews the payroll tax, Social Security's benefit formula, and outcomes by race, gender, and earnings level, and explores why low-income and minority groups do not receive greater returns on contributions. Simulates the effects of progressive reforms

The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas

Warped and eccentric discs around black holes

Accretion discs around black holes in X-ray binary stars are warped if the spin axis of the black hole is not perpendicular to the binary orbital plane. They can also become eccentric through an instability involving a resonance with the binary orbit. Depending on the thickness of the disc and the efficiency of dissipative processes, these global deformations may be able to propagate into the innermost part of the disc in the form of stationary bending or density waves. We describe the solutions in the linear regime and discuss the conditions under which a warp or eccentricity is likely to produce significant activity in the inner region, which may include the excitation of quasi-periodic oscillations.Comment: 6 pages, 3 figures; accepted for inclusion in the proceedings of "Cool Discs, Hot Flows: The Varying Faces of Accreting Compact Objects," ed. M. Axelsson (New York: AIP