Relativistic Collapse of Rotating Supermassive Stars to Supermassive Black Holes

There is compelling evidence that supermassive black holes (SMBHs) exist. Yet the origin of these objects, or their seeds, is still unknown. We are performing general relativistic simulations of gravitational collapse to black holes in different scenarios to help reveal how SMBH seeds might arise in the universe. SMBHs with ~ 10^9 solar masses must have formed by z > 6, or within 10^9 yrs after the Big Bang, to power quasars. It may be difficult for gas accretion to build up such a SMBH by this time unless the initial seed black hole already has a substantial mass. One plausible progenitor of a massive seed black hole is a supermassive star (SMS). We have followed the collapse of a SMS to a SMBH by means of 3D hydrodynamic simulations in post-Newtonian gravity and axisymmetric simulations in full general relativity. The initial SMS of arbitrary mass M in these simulations rotates uniformly at the mass--shedding limit and is marginally unstable to radial collapse. The final black hole mass and spin are determined to be M_h/M ~ 0.9 and J_h/M_h^2 ~ 0.75. The remaining mass goes into a disk of mass M_{disk}/M ~ 0.1. This disk arises even though the total spin of the progenitor star, J/M^2 = 0.97, is safely below the Kerr limit. The collapse generates a mild burst of gravitational radiation. Nonaxisymmetric bars or one-armed spirals may arise during the quasi-stationary evolution of a SMS, during its collapse, or in the ambient disk about the hole, and are potential sources of quasi-periodic waves, detectable by LISA.Comment: 11 pages, to appear in "The Astrophysics of Gravitational Wave Sources", Proceedings of a Workshop held at the University of Maryland in April 2003, ed. J. Centrella, AIP, in pres

Assessing the Benefits and Costs of Regulatory Reform: What Questions Need to be Asked

In 1984, Portney argued that "[w]e should scrutinize proposed reforms of the rulemaking process every bit as carefully as the regulations that process produces." In the twenty-three years since then, the regulatory process on the federal level has been continuously reformed by statute,by executive order, and by directives from the OMB (including the recent guidelines for risk assessments). Despite the extensive debate on the need for these reforms, there has been very little analysis of the reforms themselves. This paper updates Portney's work on analyzing cost-benefit analysis and expands it to evaluate reforms of the regulatory process. I use as my primary example the recent peer-review guidelines issued by OMB. I argue that we may have reached a point of diminishing returns in regulatory reforms and that the peer-review guidelines likely have costs that exceed their benefits and that further regulatory reforms merit closer examination. In assessing the costs of regulatory reforms, the key question is the cost of delays to the regulatory process. I look at the cost of delays extensively and identify several factors that need to be answered to assess these costs. Specifically, in order to assess the cost of regulatory delay imposed by regulatory reforms, we must know: (1) the number of regulations affected, (2) the average cost of a delay in the type of regulation that will be affected, and (3) the average length of the delay.

The Future of the Bush Administration Regulatory Reforms

The past eight years have been busy ones for aficionados of the regulatory process. Not since the late 1970s and early 1980s have as many requirements been imposed upon agencies writing a regulation. These include the implementation of the Information Quality Act, regulatory peer review, Executive Order 13422, and electronic rulemaking requirements among others. Since many of these requirements were imposed by executive order or other presidential action, the new administration will have important choices to make about whether to weaken, maintain, or strengthen these requirements. These decisions will affect nearly every area of regulatory policy This paper examines the Bush reforms by asking whether an incoming administration with different regulatory priorities will find the increased presidential power over regulatory agencies worth the other potentially deleterious effects of the reforms. I argue that several of the Bush reforms, the use of prompt letters and control over guidance documents will prove attractive to the Obama Administration, while others such as regulatory peer review and the non-guidance components of Executive Order 13422 will not.

Analysis of Homeland Security Regulations, Small Steps Forward, Giant Leaps to Go

This paper reviews the use of cost-benefit analysis in evaluating homeland security regulations. Until the recent use of "break-even analysis" by the Department of Homeland Security, analysis of regulations to reduce the risk of a terrorist attacks have been severely lacking. The costs were likely to be understated particularly because the costs of restrictions on immigration and of the curbing of civil liberties are omitted. Benefits were often left uncalculated leaving it impossible to meaningfully evaluate the policies being promulgated. The use of break-even analysis has improved the ability to evaluate homeland security policy. However, DHS needs to provide this information in a more consistent format in order to allow comparison of regulatory initiatives. DHS also needs to provide its own assessment of what the break-even analysis tells us about the likelihood that the benefits of their regulations outweigh their costs.

Presidents and Process: A Comparison of the Regulatory Process Under the Clinton and Bush (43) Administrations

Do procedural controls placed on the regulatory process allow politicians to control bureaucratic decisionmaking? I use data on the regulatory process under the Clinton and Bush Administrations to assess the differences between these presidents with distinct ideological regulatory agendas. I find that the number of comments received, the changes made between proposal and finalization of rules, the frequency with which agencies bypass notice and comment and the time to complete a rulemaking did not vary substantially between the two presidencies. This raises questions about the effectiveness of procedural controls on agency decisionmaking.Regulatory Reform