135 citations · 1.1k across the 30 of their papers we have counts for
20 papers · 1 filter
A Quasi-Periodic Modulation of the Radio Light Curve of the Blazar PKS B0048-097
M. Kadler, P. A. Hughes, E. Ros +2
In this letter we present the results of a wavelet analysis of the radio light curve of the BL Lac Object PKS B0048-097 from the University of Michigan Radio Astronomy Observatory…
Refining a relativistic, hydrodynamic solver: Admitting ultra-relativistic flows
J. P. Bernstein, P. A. Hughes
We have undertaken the simulation of hydrodynamic flows with bulk Lorentz factors in the range 10^2--10^6. We discuss the application of an existing relativistic, hydrodynamic prim…
The Origin of Complex Behavior of Linearly Polarized Components in Parsec-Scale Jets
Philip A. Hughes
Evidence that the magnetic fields of extragalactic jets have a significant fraction of their energy in a random component is briefly summarized, and a detailed model of evolving, j…
The Cross-Wavelet Transform and Analysis of Quasiperiodic Behavior in the Pearson-Readhead VLBI Survey Sources
Brandon C. Kelly, Philip A. Hughes, Hugh D. Aller +1
We introduce an algorithm for applying a cross-wavelet transform to analysis of quasiperiodic variations in a time-series, and introduce significance tests for the technique. We ap…
Pearson-Readhead Survey Sources II: The Longterm Centimeter-band Total Flux and Linear Polarization Properties of a Complete Radio Sample
M. F. Aller, H. D. Aller, P. A. Hughes
Using UMRAO centimeter-band total flux density and linear polarization monitoring observations of the complete Pearson-Readhead extragalactic source sample obtained between August…
Oblique Polarization Structures in AGN and QSO Radio Jets
H. D. Aller, M. F. Aller, P. A. Hughes
We interpret the linear polarization structures observed in extragalactic radio sources, even those oriented at oblique angles to the jet flows, to be due to oblique, relativistic…
Centimeter-band Variability in GPS Sources
M. F. Aller, H. D. Aller, P. A. Hughes +1
Monitoring results are presented for the Stangellini 1 Jy GHz-peaked-spectrum source sample, illustrating that several members exhibit variability in total flux and/or linear polar…
The Effect of External Winds on Relativistic Jets
Philip E. Hardee, Philip A. Hughes
Relativistic jets in Galactic superluminals and extragalactic AGN may be surrounded by a wind near to the central engine. Theoretical analysis and numerical simulation reveal consi…
3D Hydrodynamic Simulations of Relativistic Extragalactic Jets
Philip A. Hughes, Mark A. Miller, G. Comer Duncan
We describe a new numerical 3D relativistic hydrodynamical code, the results of validation tests, and a comparison with earlier, 2D studies. The 3D code has been used to study the…
Parsec-Scale Blazar Monitoring: Flux and Polarization Variability
Daniel C. Homan, Roopesh Ojha, John F. C. Wardle +4
We present analysis of the flux and polarization variability of parsec scale radio jets from a dual-frequency, six-epoch, VLBA polarization experiment monitoring 12 blazars. The ob…
Relativistic Jet Response to Precession and Wave-Wave Interactions
P. Hardee, P. Hughes, A. Rosen +1
Three dimensional numerical simulations of the response of a Lorentz factor 2.5 relativistic jet to precession at three different frequencies have been performed. Low, moderate and…
Light Curves from an Expanding Relativistic Jet
Jonathan Granot, Mark Miller, Tsvi Piran +2
We perform fully relativistic hydrodynamic simulations of the deceleration and lateral expansion of a relativistic jet as it expands into an ambient medium. The hydrodynamic calcul…
Confronting Hydrodynamic Simulations Of Relativistic Jets With Data: What Do We Learn About Particles & Fields?
Philip A. Hughes
We review recent relativistic hydrodynamic simulations of jets, and their interpretation in terms of the results from linear stability analysis. These studies show that, interprete…
Parsec-Scale Blazar Monitoring: Proper Motions
D. C. Homan, R. Ojha, J. F. C. Wardle +4
We present proper motions obtained from a dual frequency, six-epoch, VLBA polarization experiment monitoring a sample of 12 blazars. The observations were made at 15 GHz and 22 GHz…
Relativistic Jet Stability and Structure from the Alfven Point Outwards
P. E. Hardee, A. Rosen, P. A. Hughes +1
The amplitude of jet distortions and accompanying pressure and velocity fluctuations resulting from Kelvin-Helmholtz instability of three dimensional relativistic jets are explored…
A Comparison of the Morphology and Stability of Relativistic and Nonrelativistic Jets
A. Rosen, P. A. Hughes, G. C. Duncan +1
We compare results from a relativistic and a nonrelativistic set of 2D axisymmetric jet simulations. For a set of five relativistic simulations that either increase the Lorentz fac…
Cm-Wavelength Total Flux and Linear Polarization Properties of Radio-Loud BL Lacertae Objects
Margo F. Aller, Hugh D. Aller, Philip A. Hughes +1
Results from a long-term program to quantify the range of behavior of the cm-wavelength total flux and linear polarization variability properties of a sample of 41 radio-loud BL La…
Extraordinary Activity in the BL Lac Object OJ~287
Philip A. Hughes, Hugh D. Aller, Margo F. Aller
We use a continuous wavelet transform to analyze more than two decades of data for the BL~Lac object OJ~287 acquired as part of the UMRAO variability program. We find clear evidenc…
Simulated VLBI Images From Relativistic Hydrodynamic Jet Models
Amy J. Mioduszewski, Philip A. Hughes, G. Comer Duncan
A series of simulated maps showing the appearance in total intensity of flows computed using a recently developed relativistic hydrodynamic code (Duncan \& Hughes 1994: ApJ, 436, L…
Simulations of Relativistic Extragalactic Jets
G. Comer Duncan, Philip A. Hughes
We describe a method for the numerical solution of the relativistic Euler equations which we have found to be both robust and efficient, and which has enabled us to simulate relati…