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Full-Text Articles in Physical Sciences and Mathematics

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 …

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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 …

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Scale Invariant Jet Suppression Across The Black Hole Mass Scale, David Garofalo, Chandra B. Singh Mar 2016

Scale Invariant Jet Suppression Across The Black Hole Mass Scale, David Garofalo, Chandra B. Singh

Faculty and Research Publications

We provide a schematic framework for understanding observations of jet suppression in soft state black hole X-ray binaries based on the Blandford-Payne process and the net magnetic flux threading the black hole. Due to the geometrical thinness of soft state disks, mass-loading of field lines is ineffective compared to both geometrically thick disks as well as thin disks with greater black hole threading flux, a simple physical picture that allows us to understand the weakness of jets in radiatively efficient thin disks accreting in the prograde direction around high-spinning black holes. Despite a simplicity that forbids insights into the complexity …

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Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth Jan 2016

Reconciling Ag-Star Formation, The Soltan Argument, And Meier's Paradox, David Garofalo, Matthew I. Kim, Damian J. Christian, Emily Hollingworth

Faculty and Research Publications

We provide a theoretical context for understanding the recent work of Kalfountzou et al. showing that star formation is enhanced at lower optical luminosity in radio-loud quasars. Our proposal for coupling the assumption of collimated FRII quasar-jet-induced star formation with lower accretion optical luminosity also explains the observed jet power peak in active galaxies at higher redshift compared to the peak in accretion power, doing so in a way that predicts the existence of a family of radio-quiet active galactic nuclei associated with rapidly spinning supermassive black holes at low redshift, as mounting observations suggest. The relevance of this work …

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Symmetry And The Arrow Of Time In Theoretical Black Hole Astrophysics, David Garofalo Jun 2015

Symmetry And The Arrow Of Time In Theoretical Black Hole Astrophysics, David Garofalo

Faculty and Research Publications

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the …

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Constraints Of The Radio-Loud/Radio-Quiet Dichotomy From The Fundamental Plane, David Garofalo, Matthew I. Kim, Damian J. Christian Jun 2014

Constraints Of The Radio-Loud/Radio-Quiet Dichotomy From The Fundamental Plane, David Garofalo, Matthew I. Kim, Damian J. Christian

Faculty and Research Publications

The Fundamental Plane for black hole activity constitutes a tight correlation between jet power, X-ray luminosity, and black hole mass. Under the assumption that a Blandford–Znajek-type mechanism, which relies on black hole spin, contributes non-negligibly to jet production, the sufficiently small scatter in the Fundamental Plane shows that black hole spin differences of |Δa| ∼ 1 are not typical among the active galactic nuclei population. If – as it seems – radio-loud and radio-quiet objects are both faithful to the Fundamental Plane, models of black hole accretion in which the radio-loud/radio-quiet dichotomy is based on a spin dichotomy of a∼1/a∼0, …

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The Jet-Disk Connection: Evidence For A Reinterpretation In Radio-Loud And Radio-Quiet Active Galactic Nuclei, David Garofalo Jul 2013

The Jet-Disk Connection: Evidence For A Reinterpretation In Radio-Loud And Radio-Quiet Active Galactic Nuclei, David Garofalo

Faculty and Research Publications

To constrain models of the jet-disc connection, we explore Eddington ratios reported in Foschini (2011) and interpret them in relation to the values in Sikora et al. across the active galactic nuclei population from radio loud quasars, their flat spectrum radio quasar subclass, the recently discovered gamma-ray loud narrow-line type 1 Seyfert galaxies, Fanaroff-Riley type I (FRI) radio galaxies and radio quiet quasars of the Palomar Green survey. While appeal to disc truncation in radiatively inefficient flow appears to explain the observed inverse relation between radio loudness and Eddington ratio in radio loud and radio quiet quasars, FR I objects, …

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Retrograde Versus Prograde Models Of Accreting Black Holes, David Garofalo Feb 2013

Retrograde Versus Prograde Models Of Accreting Black Holes, David Garofalo

Faculty and Research Publications

There is a general consensus that magnetic fields, accretion disks, and rotating black holes are instrumental in the generation of the most powerful sources of energy in the known universe. Nonetheless, because magnetized accretion onto rotating black holes involves both the complications of nonlinear magnetohydrodynamics that currently cannot fully be treated numerically, and uncertainties about the origin of magnetic fields that at present are part of the input, the space of possible solutions remains less constrained. Consequently, the literature still bears witness to the proliferation of rather different black hole engine models. But the accumulated wealth of observational data is …

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Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis Dec 2010

Next-To-Next-To-Leading Soft-Gluon Corrections For The Top Quark Cross Section And Transverse Momentum Distribution, Nikolaos Kidonakis

Faculty and Research Publications

I present results for top quark production in hadronic collisions at LHC and Tevatron energies. The soft-gluon corrections to the differential cross section are resummed at next-to-next-to-leading-logarithm accuracy via the two-loop soft anomalous dimension matrices. Approximate next-to-next-to-leading-order differential and total cross sections are calculated. Detailed theoretical predictions are shown for the t (t) over bar cross section and the top quark p(T) distribution at the Tevatron and the LHC.

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Random Flows And Diagnostics Of Turbulence In The High Latitude Cirrus, Steven N. Shore, Ted N. Larosa, Raymond J. Chastain, Loris Magnani Oct 2006

Random Flows And Diagnostics Of Turbulence In The High Latitude Cirrus, Steven N. Shore, Ted N. Larosa, Raymond J. Chastain, Loris Magnani

Faculty and Research Publications

Aims: We present an analysis of the exceptionally turbulent velocity field in the high Galactic latitude cirrus cloud MBM 3. As in the other translucent clouds in our study (MBM 16 and MBM 40), there is no evidence for internal star formation. However, the large scale velocity variation in this cloud is more pronounced. Methods: We have mapped the cloud in 12CO and 13CO (1-0) at high spatial (0.03 pc) and velocity (0.06 km s-1) resolution. We constructed several velocity probability density functions (PDFs), estimated the turbulent transfer rate, and analyzed the linewidths as a function of the size of …

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The Strength And Structure Of The Galactic Center Magnetic Field, Ted La Rosa, Steven N. Shore, T. Joseph W. Lazio, Namir E. Kassim Jan 2006

The Strength And Structure Of The Galactic Center Magnetic Field, Ted La Rosa, Steven N. Shore, T. Joseph W. Lazio, Namir E. Kassim

Faculty and Research Publications

This paper summarizes recently obtained, strong evidence for a weak global field in the Galactic center (GC): the existence of a large-scale region of diffuse, low-frequency, nonthermal emission coincident with the central molecular zone. The overall energetics of this emission, considered along with constraints on GC cosmic ray energy density and diffusion, indicate clearly that the magnetic field pervading this region is ∼ 10 μG. For completeness, additional points on the orientation of the GC nonthermal filaments, rotation measures of extragalactic sources seen through the GC, and comparison with other normal spiral galaxies are also reviewed.

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Evidence Of A Weak Galactic Center Magnetic Field From Diffuse Low-Frequency Nonthermal Radio Emission, Ted La Rosa, Crystal L. Brogan, Steven N. Shore, T. Joseph Lazio, Namir E. Kassim, Michael E. Nord Jun 2005

Evidence Of A Weak Galactic Center Magnetic Field From Diffuse Low-Frequency Nonthermal Radio Emission, Ted La Rosa, Crystal L. Brogan, Steven N. Shore, T. Joseph Lazio, Namir E. Kassim, Michael E. Nord

Faculty and Research Publications

New low-frequency 74 and 330 MHz observations of the Galactic center (GC) region reveal the presence of a large-scale (6° × 2°) diffuse source of nonthermal synchrotron emission. A minimum-energy analysis of this emission yields a total energy of ~(phi4/7f3/7) × 1052 ergs and a magnetic field strength of ~6(phi/f)2/7 μG (where phi is the proton to electron energy ratio and f is the filling factor of the synchrotron emitting gas). The equipartition particle energy density is 1.2(phi/f)2/7 eV cm-3, a value consistent with cosmic-ray data. However, the derived magnetic field is several orders of magnitude below the 1 mG …

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High-Resolution, Wide-Field Imaging Of The Galactic Center Region At 330 Mhz, Michael E. Nord, T. Joseph W. Lazio, Namir E. Kassim, Scott D. Hyman, Ted W. La Rosa, Crystal L. Brogan, Nebojsa Duric Oct 2004

High-Resolution, Wide-Field Imaging Of The Galactic Center Region At 330 Mhz, Michael E. Nord, T. Joseph W. Lazio, Namir E. Kassim, Scott D. Hyman, Ted W. La Rosa, Crystal L. Brogan, Nebojsa Duric

Faculty and Research Publications

We present a wide-field, subarcminute-resolution VLA image of the Galactic center region at 330 MHz. With a resolution of ~7'' × 12'' and an rms noise of 1.6 mJy beam-1, this image represents a significant increase in resolution and sensitivity over the previously published VLA image at this frequency. The improved sensitivity has more than tripled the census of small-diameter sources in the region, has resulted in the detection of two new nonthermal filaments (NTFs), 18 NTF candidates, and 30 pulsar candidates, reveals previously known extended sources in greater detail, and has resulted in the first detection of …

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New Nonthermal Filaments At The Galactic Center: Are They Tracing A Globally Ordered Magnetic Field?, Ted La Rosa, Michael E. Nord, Joseph W. Lazlo, Namir E. Kassim May 2004

New Nonthermal Filaments At The Galactic Center: Are They Tracing A Globally Ordered Magnetic Field?, Ted La Rosa, Michael E. Nord, Joseph W. Lazlo, Namir E. Kassim

Faculty and Research Publications

New high-resolution, wide-field 90 cm VLA observations of the Galactic center (GC) region by Nord and coworkers have revealed 20 nonthermal filament (NTF) candidates. We report 6 cm polarization observations of six of these. All of the candidates have the expected NTF morphology, and two show extended polarization, confirming their identification as NTFs. One of the new NTFs appears to be part of a system of NTFs located in the Sgr B region, 64 pc in projection north of Sgr A. These filaments cross the Galactic plane with an orientation similar to the filaments in the Galactic center radio arc. …

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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.

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High Resolution, High Sensitivity Imaging Of The Galactic Center At 330 Mhz, Michael E. Nord, Crystal L. Brogan, Scott D. Hyman, T. Joseph W. Lazio, Namir E. Kassim, Ted N. Larosa, K. Anantharamaiah, Nebojsa Duric Sep 2003

High Resolution, High Sensitivity Imaging Of The Galactic Center At 330 Mhz, Michael E. Nord, Crystal L. Brogan, Scott D. Hyman, T. Joseph W. Lazio, Namir E. Kassim, Ted N. Larosa, K. Anantharamaiah, Nebojsa Duric

Faculty and Research Publications

We present results derived from a wide field, sub-arcminute resolution VLA image of the Galactic Center region at 330 MHz (λ = 90 cm). With a resolution of ∼7″ × 12″ and an rms noise of 1.6 mJy beam−1, this image represents a significant increase in resolution and sensitivity over the previously published VLA image at this frequency (eg. LaRosa et al. 2000). The improvement in sensitivity has significantly increased the census of small diameter sources in the region, resulted in the detection of two new Non-Thermal Filaments (NTFs) and 18 new NTF candidates, and resulted in …

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The Galactic Center Nonthermal Filaments: Recent Observations And Theory, Ted La Rosa, Michael E. Nord, T. Joseph W. Lazio, Steven N. Shore, Namir E. Kassim Sep 2003

The Galactic Center Nonthermal Filaments: Recent Observations And Theory, Ted La Rosa, Michael E. Nord, T. Joseph W. Lazio, Steven N. Shore, Namir E. Kassim

Faculty and Research Publications

The large-scale topology and strength of the Galactic Center magnetic field have been inferred from radio imaging of the nonthermal filaments (NTFs). These objects, which seem to be unique to the Galactic center, are defined by extreme aspect ratios and a high degree of polarization. Recent high resolution, wide-field VLA imaging of the GC at 90 cm has revealed new candidate NTFs with a wide range of orientations relative to the Galactic plane. We present follow up 6 cm polarization observations of 6 of these candidates and confirm 4 as new NTFs. Together the new 90 and 6 cm results …

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Mechanisms For The Origin Of Turbulence In Non-Star-Forming Clouds: The Translucent Cloud Mbm 40, Steven N. Shore, Loris Magnani, Ted La Rosa, Meredith N. Mccarthy Aug 2003

Mechanisms For The Origin Of Turbulence In Non-Star-Forming Clouds: The Translucent Cloud Mbm 40, Steven N. Shore, Loris Magnani, Ted La Rosa, Meredith N. Mccarthy

Faculty and Research Publications

We present a multiline, high spatial and velocity resolution CO, H I, and IRAS 100 μm study of the high-latitude, low-mass, non-star-forming, translucent molecular cloud MBM 40. The cloud mass is distributed into two ridges, or filaments, that form a hairpin structure. Velocity channel maps indicate a highly ordered flow in the molecular gas, with the northeastern part of the filament moving away from and the southwestern filament moving toward the observer relative to the mean cloud radial velocity. Significant changes in emissivity occur over 0.03 pc, indicating large transverse density gradients along the ridges. However, the velocity field appears …

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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 …

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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 …

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A New System Of Parallel Isolated Nonthermal Filaments Near The Galactic Center: Evidence For A Local Magnetic Field Gradient, Ted N. La Rosa, Joseph W. Lazio, Nasir E. Kassim Dec 2001

A New System Of Parallel Isolated Nonthermal Filaments Near The Galactic Center: Evidence For A Local Magnetic Field Gradient, Ted N. La Rosa, Joseph W. Lazio, Nasir E. Kassim

Faculty and Research Publications

We report the discovery of a system of isolated nonthermal filaments approximately 0fdg5 northwest (75 pc in projection) of Sgr A. Unlike other isolated nonthermal filaments which show subfilamentation, braiding of subfilaments, and flaring at their ends, these filaments are simple linear structures and more closely resemble the parallel bundled filaments in the Galactic center radio arc. However, the most unusual feature of these filaments is that the 20/90 cm spectral index uniformly decreases as a function of length, in contrast to all other nonthermal filaments in the Galactic center. This spectral gradient may not be due to simple particle …

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A Wide Field 90 Cm Vla Image Of The Galactic Center Region, Ted La Rosa, Namir E. Kassim, Joseph W. Lazlo, Scott B. Hyman Jan 2000

A Wide Field 90 Cm Vla Image Of The Galactic Center Region, Ted La Rosa, Namir E. Kassim, Joseph W. Lazlo, Scott B. Hyman

Faculty and Research Publications

We present a wide-field, high dynamic range, high-resolution, long-wavelength (lambda = 90 cm) VLA image of the Galactic center region. The image is centered on Sgr A, covers an area of 4 degrees x 5 degrees with an angular resolution of 43 ", and has a rms sensitivity of approximate to 5 mJy beam-l. The image was constructed from archival (1989 and 1991) VLA data of Pedlar et al. and Anantharamaiah et al. using new three-dimensional image restoration techniques. These three-dimensional imaging techniques resolve the problem of non-coplanar baselines encountered at long wavelengths and yield distortion-free imaging of far-field sources …

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The Galactic Center Isolated Nonthermal Filaments As Analogs Of Cometary Plasma Tails, Steven N. Shore, Ted La Rosa Aug 1999

The Galactic Center Isolated Nonthermal Filaments As Analogs Of Cometary Plasma Tails, Steven N. Shore, Ted La Rosa

Faculty and Research Publications

We propose a model for the origin of the isolated nonthermal filaments observed at the Galactic center based on an analogy to cometary plasma tails. We invoke the interaction between a large-scale magnetized galactic wind and embedded molecular clouds. As the advected wind magnetic field encounters a dense molecular cloud, it is impeded and drapes around the cloud, ultimately forming a current sheet in the wake. This draped held is further stretched by the wind flow into a long, thin filament the aspect ratio of which is determined by the balance between the dynamical wind and amplified magnetic field pressures. …

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A Dynamical Study Of The Non-Star-Forming Translucent Molecular Cloud Mbm 16: Evidence For Shear-Driven Turbulence In The Interstellar Medium, Ted La Rosa, Steven N. Shore, Loris Magnani Feb 1999

A Dynamical Study Of The Non-Star-Forming Translucent Molecular Cloud Mbm 16: Evidence For Shear-Driven Turbulence In The Interstellar Medium, Ted La Rosa, Steven N. Shore, Loris Magnani

Faculty and Research Publications

We present the results of a velocity correlation study of the high-latitude cloud MBM 16 using a fully sampled 12CO map, supplemented by new 13CO data. We find a correlation length of 0.4 pc. This is similar in size to the formaldehyde clumps described in our previous study. We associate this correlated motion with coherent structures within the turbulent flow. Such structures are generated by free shear flows. Their presence in this non-star-forming cloud indicates that kinetic energy is being supplied to the internal turbulence by an external shear flow. Such large-scale driving over long times is a possible solution …

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Production Of Energy-Dependent Time Delays In Impulsive Solar Flare Hard X-Ray Emission By Short-Duration Spectral Index Variations, Ted N. La Rosa, Steven N. Shore Aug 1998

Production Of Energy-Dependent Time Delays In Impulsive Solar Flare Hard X-Ray Emission By Short-Duration Spectral Index Variations, Ted N. La Rosa, Steven N. Shore

Faculty and Research Publications

Cross-correlation techniques have been used recently to study the relative timing of solar flare hard X-ray emission at different energies. These studies find that for the majority of the impulsive flares observed with BATSE there is a systematic time delay of a few tens of milliseconds between low (approximate to 50 keV) and higher energy emission (approximate to 100 keV). These time delays have been interpreted as energy-dependent time-of-flight differences for electron propagation from the corona, where they are accelerated, to the chromosphere, where the bulk of the hard X-rays are emitted. We show in this paper that crosscorrelation methods …

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Critical Issues For Understanding Particle Acceleration In Impulsive Solar Flares, James A. Miller, Peter J. Cargill, A. Gordon Emslie, Gordon D. Holman, Brian R. Dennis, Ted N. La Rosa, Robert M. Winglee, Stephen G. Benka, S. Tsuneta Jul 1997

Critical Issues For Understanding Particle Acceleration In Impulsive Solar Flares, James A. Miller, Peter J. Cargill, A. Gordon Emslie, Gordon D. Holman, Brian R. Dennis, Ted N. La Rosa, Robert M. Winglee, Stephen G. Benka, S. Tsuneta

Faculty and Research Publications

This paper, a review of the present status of existing models for particle acceleration during impulsive solar flares, was inspired by a week-long workshop held in the Fall of 1993 at NASA Goddard Space Flight Center. Recent observations from Yohkoh and the Compton Gamma Ray Observatory, and a reanalysis of older observations from the Solar Maximum Mission, have led to important new results concerning the location, timing, and efficiency of particle acceleration in flares. These are summarized in the first part of the review. Particle acceleration processes are then discussed, with;particular emphasis on new developments in stochastic acceleration by magnetohydrodynamic …

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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 …

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Stochastic Electron Acceleration By Cascading Fast Mode Waves In Impulsive Solar Flares, James A. Miller, Ted N. La Rosa, Ronald L. Moore Apr 1996

Stochastic Electron Acceleration By Cascading Fast Mode Waves In Impulsive Solar Flares, James A. Miller, Ted N. La Rosa, Ronald L. Moore

Faculty and Research Publications

We present a model for the acceleration of electrons from thermal to ultrarelativistic energies during an energy release fragment in an impulsive solar flare. Long-wavelength low-amplitude fast mode waves are assumed to be generated during the initial flare energy release (by, for example, large-scale restructuring of the magnetic field). These waves nonlinearly cascade to higher wavenumbers and eventually reach the dissipation range, whereupon they are transit-time damped by electrons in the tail of the thermal distribution. The electrons, in turn, are energized out of the tail and into substantially higher energies. We find that for turbulence energy densities much smaller …

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The Wall Of Reconnection-Driven Magnetohydrodynamic Turbulence In A Large Solar-Flare, Ronald L. Moore, Ted N. La Rosa, L. E. Orwig Jan 1995

The Wall Of Reconnection-Driven Magnetohydrodynamic Turbulence In A Large Solar-Flare, Ronald L. Moore, Ted N. La Rosa, L. E. Orwig

Faculty and Research Publications

LaRosa & Moore (1993) recently proposed that the bulk dissipation of magnetic field that is required for the electron energization in the explosive phase of solar flares occurs in a ''fat current sheet,'' a wall of cascading MHD turbulence sustained by highly disordered driven reconnection of opposing magnetic fields impacting at a turbulent boundary layer. In two-ribbon eruptive flares, this turbulent reconnection wall is supposed to develop at the usual reconnection site in the standard model for these flares; that is, the reconnection wall stands in the vertical magnetic rent made by the eruption of the sheared core of the …

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