Correlations of near-infrared, optical and X-ray luminosity for early-type galaxies

The relation between X-ray luminosity and near-infrared luminosity for early-type galaxies has been examined. Near-infrared (NIR) luminosities should provide a superior measure of stellar mass compared to optical luminosities used in previous studies, especially if there is significant star-formation or dust present in the galaxies. However, we show that the X-ray-NIR relations are remarkably consistent with the X-ray-optical relations. This indicates that the large scatter of the relations is dominated by scatter in the X-ray properties of early-type galaxies, and is consistent with early-types consisting of old, quiescent stellar populations. We have investigated scatter in terms of environment, surface brightness profile, Mg2, H_beta, H_gamma line strength indices, spectroscopic age, and nuclear H_alpha emission. We found that galaxies with high Mg2 index, low H_beta and H_gamma indices or a `core' profile have a large scatter in Lx, whereas galaxies with low Mg2, high H_beta and H_gamma indices or `power-law' profiles, generally have Lx<10^41 erg/s. There is no clear trend in the scatter with environment or nuclear H_alpha emission.Comment: Accepted for publication in MNRAS. 22 pages, 15 figure

The dynamics of internal working surfaces in MHD jets

The dynamical effects of magnetic fields in models of radiative, Herbig-Haro (HH) jets have been studied in a number of papers. For example, magnetized, radiative jets from variable sources have been studied with axisymmetric and 3D numerical simulations. In this paper, we present an analytic model describing the effect of a toroidal magnetic field on the internal working surfaces that result from a variability in the ejection velocity. We find that for parameters appropriate for HH jets the forces associated with the magnetic field dominate over the gas pressure force within the working surfaces. Depending on the ram pressure radial cross section of the jet, the magnetic field can produce a strong axial pinch, or, alternatively, a broadening of the internal working surfaces. We check the validity of the analytic model with axisymmetric numerical simulations of variable, magnetized jets.Comment: 14 pages, 4 figures. ApJ in pres

A National Portrait of Domestic Violence Courts

A growing number of criminal courts nationwide handle domestic violence cases on separate calendars, termed domestic violence courts. There are now 208 confirmed domestic violence courts across the U.S. (Center for Court Innovation 2009). More than 150 similar projects have been established internationally. Some domestic violence courts emerged in the context of the broader "problem-solving court" movement and share characteristics with other specialized courts, such as separate dockets and specially trained judges. However, the origins of domestic violence courts are also distinct, growing out of the increased attention afforded domestic violence matters by the justice system over the past 30 years. With funding from the National Institute of Justice, this study explores how criminal domestic violence courts have evolved, their rationale, and how their operations vary across the U.S. This study does not test whether domestic violence courts reduce recidivism, protect victims, or achieve other specific effects -- although we provide a thorough literature review on these points. Rather, our aim is to present a comprehensive national portrait of the field as it exists today, laying the groundwork for future information exchange and research

Broadband, radio spectro-polarimetric study of 100 radiative-mode and jet-mode AGN

We present the results from a broadband (1 to 3 GHz), spectro-polarimetry study of the integrated emission from 100 extragalactic radio sources with the ATCA, selected to be highly linearly polarized at 1.4 GHz. We use a general purpose, polarization model-fitting procedure that describes the Faraday rotation measure (RM) and intrinsic polarization structure of up to three distinct polarized emission regions or 'RM components' of a source. Overall, 37%/52%/11% of sources are best fit by one/two/three RM components. However, these fractions are dependent on the signal-to-noise ratio (S/N) in polarization (more RM components more likely at higher S/N). In general, our analysis shows that sources with high integrated degrees of polarization at 1.4 GHz have low Faraday depolarization, are typically dominated by a single RM component, have a steep spectral index, and a high intrinsic degree of polarization. After classifying our sample into radiative-mode and jet-mode AGN, we find no significant difference between the Faraday rotation or Faraday depolarization properties of jet-mode and radiative-mode AGN. However, there is a statistically significant difference in the intrinsic degree of polarization between the two types, with the jet-mode sources having more intrinsically ordered magnetic field structures than the radiative-mode sources. We also find a preferred perpendicular orientation of the intrinsic magnetic field structure of jet-mode AGN with respect to the jet direction, while no clear preference is found for the radiative-mode sources.Comment: 29 pages (including Appendix), 28 figures, 7 tables. Accepted for publication in MNRA

The Influence of Shale gas on U.S. Energy and Environmental Policy

http://globalchange.mit.edu/research/publications/2219The emergence of U.S. shale gas resources to economic viability affects the nation’s energy outlook and the expected role of natural gas in climate policy. Even in the face of the current shale gas boom, however, questions are raised about both the economics of this industry and the wisdom of basing future environmental policy on projections of large shale gas supplies. Analysis of the business model appropriate to the gas shales suggests that, though the shale future is uncertain, these concerns are overstated. The policy impact of the shale gas is analyzed using two scenarios of greenhouse gas control—one mandating renewable generation and coal retirement, the other using price to achieve a 50% emissions reduction. The shale gas is shown both to benefit the national economy and to ease the task of emissions control. However, in treating the shale as a “bridge” to a low carbon future there are risks to the development of technologies, like capture and storage, needed to complete the task.This paper was supported by the U.S. Department of Energy, Office of Science (DE-FG02-94ER61937); the U.S. Environmental Protection Agency; the Electric Power Research Institute; and other U.S. government agencies and a consortium of 40 industrial and foundation sponsors