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Articles 1 - 10 of 10
Full-Text Articles in Physical Sciences and Mathematics
Powerful Activity In The Bright Ages. I. A Visible/Ir Survey Of High Redshift 3c Radio Galaxies And Quasars, Bryan Hilbert, Eric S. Perlman
Powerful Activity In The Bright Ages. I. A Visible/Ir Survey Of High Redshift 3c Radio Galaxies And Quasars, Bryan Hilbert, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present new rest-frame UV and visible observations of 22 high-z (1 < z < 2.5) 3C radio galaxies and QSOs obtained with the Hubble Space Telescope's Wide Field Camera 3 instrument. Using a custom data reduction strategy in order to assure the removal of cosmic rays, persistence signal, and other data artifacts, we have produced high-quality science-ready images of the targets and their local environments. We observe targets with regions of UV emission suggestive of active star formation. In addition, several targets exhibit highly distorted host galaxy morphologies in the rest frame visible images. Photometric analyses reveal that brighter QSOs generally tend to be redder than their dimmer counterparts. Using emission line fluxes from the literature, we estimate that emission line contamination is relatively small in the rest frame UV images for the QSOs. Using archival VLA data, we have also created radio map overlays for each of our targets, allowing for analysis of the optical and radio axes alignment.
New Constraints On Quantum Gravity From X-Ray And Gamma-Ray Observations, Eric S. Perlman, Saul A. Rappaport, Wayne A. Christiansen, Yeejack Ng, John G. Devore, David A. Pooley
New Constraints On Quantum Gravity From X-Ray And Gamma-Ray Observations, Eric S. Perlman, Saul A. Rappaport, Wayne A. Christiansen, Yeejack Ng, John G. Devore, David A. Pooley
Aerospace, Physics, and Space Science Faculty Publications
One aspect of the quantum nature of spacetime is its “foaminess” at very small scales. Many models for spacetime foam are defined by the accumulation power α, which parameterizes the rate at which Planck-scale spatial uncertainties (and the phase shifts they produce) may accumulate over large path lengths. Here α is defined by the expression for the path-length fluctuations, dℓ, of a source at distance ℓ, wherein dℓ ℓ1-aℓ a P , with ℓP being the Planck length. We reassess previous proposals to use astronomical observations of distant quasars and active galactic nuclei to test models of spacetime foam. …
Polarimetry And The High-Energy Emission Mechanisms In Quasar Jets: The Case Of Pks 1136-135, Mihai Cara, Eric S. Perlman
Polarimetry And The High-Energy Emission Mechanisms In Quasar Jets: The Case Of Pks 1136-135, Mihai Cara, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
Since the discovery of kiloparsec-scale X-ray emission from quasar jets, the physical processes responsible for their high-energy emission have been poorly defined. A number of mechanisms are under active debate, including synchrotron radiation, inverse-Comptonized cosmic microwave background (IC/CMB) emission, and other Comptonization processes. In a number of cases, the optical and X-ray emission of jet regions are inked by a single spectral component, and in those, high-resolution multi-band imaging and polarimetry can be combined to yield a powerful diagnostic of jet emission processes. Here we report on deep imaging photometry of the jet of PKS 1136−135 obtained with the Hubble …
A Method For Localizing Energy Dissipation In Blazars Using Fermi Variability, Amanda Dotson, Markos Georganopoulos, Demosthenes Kazanas, Eric S. Perlman
A Method For Localizing Energy Dissipation In Blazars Using Fermi Variability, Amanda Dotson, Markos Georganopoulos, Demosthenes Kazanas, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
The distance of a Fermi-detected blazar γ-ray emission site from a supermassive black hole is a matter of active debate. Here we present a method for testing if the GeV emission of powerful blazars is produced within the subparsec-scale broad-line region (BLR) or farther out in the parsec-scale molecular torus (MT) environment If the GeV emission takes place within the BLR, the inverse Compton (IC) scattering of the BLR ultraviolet (UV) seed photons that produces the γ-rays takes place at the onset of the Klein–Nishina regime. This causes the electron cooling time to become practically energy-independent and the variation of …
Using Observations Of Distant Quasars To Constrain Quantum Gravity, Eric S. Perlman, Yeejack Ng, David J.E. Floyd, Wayne A. Christiansen
Using Observations Of Distant Quasars To Constrain Quantum Gravity, Eric S. Perlman, Yeejack Ng, David J.E. Floyd, Wayne A. Christiansen
Aerospace, Physics, and Space Science Faculty Publications
Aims. The small-scale nature of spacetime can be tested with observations of distant quasars. We comment on a recent paper by Tamburini et al. (2011, A&A, 533, A71) which claims that Hubble Space Telescope (HST) observations of the most distant quasars place severe constraints on models of foamy spacetime. Methods. If space is foamy on the Planck scale, photons emitted from distant objects will accumulate uncertainties in distance and propagation directions thus affecting the expected angular size of a compact object as a function of redshift. We discuss the geometry of foamy spacetime, and the appropriate distance measure for calculating …
Hubble Space Telescope Near-Infrared Snapshot Survey Of 3cr Radio Source Counterparts. Iii. Radio Galaxies And Quasars In Context, David J.E. Floyd, David Axon, Stefi Baum, Alessandro Capetti, Marco Chiaberge, Juan P. Madrid, Christopher P. O'Dea, Eric S. Perlman, William B. Sparks
Hubble Space Telescope Near-Infrared Snapshot Survey Of 3cr Radio Source Counterparts. Iii. Radio Galaxies And Quasars In Context, David J.E. Floyd, David Axon, Stefi Baum, Alessandro Capetti, Marco Chiaberge, Juan P. Madrid, Christopher P. O'Dea, Eric S. Perlman, William B. Sparks
Aerospace, Physics, and Space Science Faculty Publications
We compare the near-infrared (NIR) H-band photometric and morphological properties of low-z (z < 0.3) 3CR radio galaxies with samples of BL Lac objects and quasar host galaxies, merger remnants, quiescent elliptical galaxies, and brightest cluster galaxies drawn from the literature. In general, the 3CR host galaxies are consistent with luminous (~Lsstarf) elliptical galaxies. The vast majority of FR II's (~80%) occupy the most massive ellipticals and form a homogeneous population that is comparable to the population of radio-loud quasar (RLQ) host galaxies in the literature. However, a significant minority (~20%) of the 3CR FR II's appears under-luminous with respect to quasar host galaxies. All FR II objects in this faint tail are either unusually red, or appear to be the brightest objects within a group. We discuss the apparent differences between the radio galaxy and RLQ host galaxy populations. RLQs appear to require gsim1011 M☉ host galaxies (and ~109 M☉ black holes), whereas radio galaxies and radio-quiet quasars can exist in galaxies down to ~3 × 1010 M☉. This may be due to biases in the measured quasar host galaxy luminosities or populations studied, or due to a genuine difference in host galaxy. If due to a genuine difference, it would support the idea that radio and optical active galactic nuclei are two separate populations with a significant overlap.
A Multizone Model For Simulating The High-Energy Variability Of Tev Blazars, Philip B. Graff, Markos Georganopoulos, Eric S. Perlman, Demosthenes Kazanas
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
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 …
The Deep X-Ray Radio Blazar Survey. Iii. Radio Number Counts, Evolutionary Properties, And Luminosity Function Of Blazars, Paolo Padovani, Paolo Giommi, Hermine Landt, Eric S. Perlman
The Deep X-Ray Radio Blazar Survey. Iii. Radio Number Counts, Evolutionary Properties, And Luminosity Function Of Blazars, Paolo Padovani, Paolo Giommi, Hermine Landt, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
Our knowledge of the blazar surface densities and luminosity functions, which are fundamental parameters, relies still on samples at relatively high flux limits. As a result, our understanding of this rare class of active galactic nuclei is mostly based on relatively bright and intrinsically luminous sources. We present the radio number counts, evolutionary properties, and luminosity functions of the faintest blazar sample with basically complete (∼95%) identifications. Based on the Deep X-Ray Radio Blazar Survey (DXRBS), it includes 129 flat-spectrum radio quasars ( FSRQs) and 24 BL Lac objects down to a 5 GHz flux and power ∼50 mJy and …
Pks 0736+017: A Striking Optical Flare And Intriguing Microvariability, Sandra D. Clements, A Jenks, Y Torres
Pks 0736+017: A Striking Optical Flare And Intriguing Microvariability, Sandra D. Clements, A Jenks, Y Torres
Aerospace, Physics, and Space Science Faculty Publications
The compact, flat-spectrum radio quasar PKS 0736+017 was monitored for microvariability on 10 nights in early 2002 using the 0.9 m SARA telescope on Kitt Peak in Arizona. On January 14, PKS 0736+017 flared dramatically, brightening by 1.3 R mag in 2 hours. Prior to the flare, PKS 0736+017 exhibited quasi-periodic variations. During and after the flare, more complex oscillations occurred. Impressive variability was displayed on two additional nights in January, while observations during the following 3 months found PKS 0736+017 to be fairly quiescent. PKS 0736+017 was somewhat redder while brighter and fading than when dimmer but flaring. During …