Open Access. Powered by Scholars. Published by Universities.®

Cosmology, Relativity, and Gravity Commons™

Open Access. Powered by Scholars. Published by Universities.®

Faculty and Research Publications

Articles 1 - 6 of 6

Full-Text Articles in Cosmology, Relativity, and Gravity

Magnetic Fields Threading Black Holes: Restrictions From General Relativity And Implications For Astrophysical Black Holes, David Garofalo Jun 2017

Magnetic Fields Threading Black Holes: Restrictions From General Relativity And Implications For Astrophysical Black Holes, David Garofalo

Faculty and Research Publications

The idea that black hole spin is instrumental in the generation of powerful jets in active galactic nuclei and X-ray binaries is arguably the most contentious claim in black hole astrophysics. Because jets are thought to originate in the context of electromagnetism, and the modeling of Maxwell fields in curved spacetime around black holes is challenging, various approximations are made in numerical simulations that fall under the guise of ‘ideal magnetohydrodynamics’. But the simplifications of this framework may struggle to capture relevant details of real astrophysical environments near black holes. In this work, we highlight tension between analytic and numerical …

Go to article

Possible Evolution Of Supermassive Black Holes From Fri Quasars, Matthew I. Kim, Damian J. Christian, David Garofalo, Jaclyn D'Avanzo May 2016

Possible Evolution Of Supermassive Black Holes From Fri Quasars, Matthew I. Kim, Damian J. Christian, David Garofalo, Jaclyn D'Avanzo

Faculty and Research Publications

We explore the question of the rapid buildup of black hole mass in the early universe employing a growing black hole mass-based determination of both jet and disc powers predicted in recent theoretical work on black hole accretion and jet formation. Despite simplified, even artificial assumptions about accretion and mergers, we identify an interesting low probability channel for the growth of one billion solar mass black holes within hundreds of millions of years of the big bang without appealing to super Eddington accretion. This result is made more compelling by the recognition of a connection between this channel and an …

Go to article

Complex Multiplication Symmetry Of Black Hole Attractors, Monika Lynker, Vipul Periwal, Rolf Schimmrigk Sep 2003

Complex Multiplication Symmetry Of Black Hole Attractors, Monika Lynker, Vipul Periwal, Rolf Schimmrigk

Faculty and Research Publications

We show how Moore’s observation, in the context of toroidal compactifications in type IIB string theory, concerning the complex multiplication structure of black hole attractor varieties, can be generalized to Calabi-Yau compactifications with finite fundamental groups. This generalization leads to an alternative general framework in terms of motives associated to a Calabi-Yau variety in which it is possible to address the arithmetic nature of the attractor varieties in a universal way via Deligne’s period conjecture.

Go to article

Black Hole Attractor Varieties And Complex Multiplication, Monika Lynker, Vipul Periwal, Rolf Schimmrigk Jun 2003

Black Hole Attractor Varieties And Complex Multiplication, Monika Lynker, Vipul Periwal, Rolf Schimmrigk

Faculty and Research Publications

Black holes in string theory compactified on Calabi-Yau varieties a priori might be expected to have moduli dependent features. For example the entropy of the black hole might be expected to depend on the complex structure of the manifold. This would be inconsistent with known properties of black holes. Supersymmetric black holes appear to evade this inconsistency by having moduli fields that flow to fixed points in the moduli space that depend only on the charges of the black hole. Moore observed in the case of compactifications with elliptic curve factors that these fixed points are arithmetic, corresponding to curves …

Go to article

Modeling The Galactic Center Nonthermal Filaments As Magnetized Wakes, Russell B. Dahlburg, Giorgio Einaudi, Ted N. La Rosa, Steven N. Shore Mar 2002

Modeling The Galactic Center Nonthermal Filaments As Magnetized Wakes, Russell B. Dahlburg, Giorgio Einaudi, Ted N. La Rosa, Steven N. Shore

Faculty and Research Publications

We simulate the Galactic center nonthermal laments as magnetized wakes formed dynamically from amplification of a weak ( tens of l G) global magnetic field through the interaction of molecular clouds with a Galactic center wind. One of the key issues in this cometary model is the stability of the lament against dynamical disruption. Here we show two-dimensional MHD simulations for interstellar conditions that are appropriate for the Galactic center. The structures eventually disrupt through a shear-driven nonlinear instability but maintain coherence for lengths up to 100 times their width as observed. The final instability, which destroys the lament through …

Go to article

New Promise For Electron Bulk Energization In Solar Flares: Preferential Fermi Acceleration Of Electrons Over Protons In Reconnection-Driven Magnetohydrodynamic Turbulence, Ted La Rosa, Ronald L. Moore, James A. Miller, Steven N. Shore Aug 1996

New Promise For Electron Bulk Energization In Solar Flares: Preferential Fermi Acceleration Of Electrons Over Protons In Reconnection-Driven Magnetohydrodynamic Turbulence, Ted La Rosa, Ronald L. Moore, James A. Miller, Steven N. Shore

Faculty and Research Publications

The hard X-ray luminosity of impulsive solar flares indicates that electrons in the low corona are bulk energized to energies of order 25 keV. LaRosa & Moore pointed out that the required bulk energization could be produced by cascading MHD turbulence generated by Alfvénic outflows from sites of strongly driven reconnection. LaRosa, Moore, & Shore proposed that the compressive component of the cascading turbulence dissipates into the electrons via Fermi acceleration. However, for this to be a viable electron bulk energization mechanism, the rate of proton energization by the same turbulence cannot exceed the electron energization rate. In this paper …

Go to article