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Physical Sciences and Mathematics Commons

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

Astrophysics and Astronomy

Aerospace, Physics, and Space Science Faculty Publications

2008

Galaxies: Active

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

A Multizone Model For Simulating The High-Energy Variability Of Tev Blazars, Philip B. Graff, Markos Georganopoulos, Eric S. Perlman, Demosthenes Kazanas Dec 2008

A Multizone Model For Simulating The High-Energy Variability Of Tev Blazars, Philip B. Graff, Markos Georganopoulos, Eric S. Perlman, Demosthenes Kazanas

Aerospace, Physics, and Space Science Faculty Publications

We present a time-dependent multizone code for simulating the variability of synchrotron self-Compton (SSC) sources. The code adopts a multizone pipe geometry for the emission region, appropriate for simulating emission from a standing or propagating shock in a collimated jet. Variations in the injection of relativistic electrons in the inlet propagate along the length of the pipe, cooling radiatively. Our code for the first time takes into account the nonlocal, time-retarded nature of SSC losses that are thought to be dominant in TeV blazars. The observed synchrotron and SSC emission is followed self-consistently, taking into account light-travel time delays. At …


A Novel Method For Measuring The Extragalactic Background Light: Fermi Application To The Lobes Of Fornax A, Markos Georganopoulos, Rita M. Sambruna, Demosthenes Kazanas, Analia N. Cillis, Chi C. Cheung, Eric S. Perlman, Katherine M. Blundell, David S. Davis Oct 2008

A Novel Method For Measuring The Extragalactic Background Light: Fermi Application To The Lobes Of Fornax A, Markos Georganopoulos, Rita M. Sambruna, Demosthenes Kazanas, Analia N. Cillis, Chi C. Cheung, Eric S. Perlman, Katherine M. Blundell, David S. Davis

Aerospace, Physics, and Space Science Faculty Publications

We describe a new method for measuring the extragalactic background light (EBL) through the detection of γ-ray inverse Compton (IC) emission due to scattering of the EBL photons off relativistic electrons in the lobes of radio galaxies. Our method has no free physical parameters and is a powerful tool when the lobes are characterized by a high-energy sharp break or cutoff in their electron energy distribution (EED). We show that such a feature will produce a high-energy IC “imprint” of the EBL spectrum in which the radio lobes are embedded and show how this imprint can be used to derive …


Hubble Space Telescope Near-Infrared Snapshot Survey Of 3cr Radio Source Counterparts. Ii. An Atlas And Inventory Of The Host Galaxies, Mergers, And Companions, David J. E. Floyd, Eric Perlman Jan 2008

Hubble Space Telescope Near-Infrared Snapshot Survey Of 3cr Radio Source Counterparts. Ii. An Atlas And Inventory Of The Host Galaxies, Mergers, And Companions, David J. E. Floyd, Eric Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present the second part of an H-band (1.6 μm) "atlas" of z < 0.3 3CR radio galaxies, using the Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer (HST NICMOS2). We present new imaging for 21 recently acquired sources and host galaxy modeling for the full sample of 101 (including 11 archival) - an 87% completion rate. Two different modeling techniques are applied, following those adopted by the galaxy morphology and the quasar host galaxy communities. Results are compared and found to be in excellent agreement, although the former breaks down in the case of sources with strong active galactic nuclei (AGNs). Companion sources are tabulated, and the presence of mergers, tidal features, dust disks, and jets are cataloged. The tables form a catalog for those interested in the structural and morphological dust-free host galaxy properties of the 3CR sample, and for comparison with morphological studies of quiescent galaxies and quasar host galaxies. Host galaxy masses are estimated and found to typically lie at around 2 × 1011 M⊙. In general, the population is found to be consistent with the local population of quiescent elliptical galaxies, but with a longer tail to low Sérsic index, mainly consisting of low-redshift (z < 0.1) and low-radio-power (FR I) sources. A few unusually disky FR II host galaxies are picked out for further discussion. Nearby external sources are identified in the majority of our images, many of which we argue are likely to be companion galaxies or merger remnants. The reduced NICMOS data are now publicly available from our Web site.