Digital Commons Network^™

Multiwavelength Observations Of The Blazar Markarian 421 In 2002 December And 2003 January, P. T. Reynolds, Veritas

Physical Sciences Publications

We report on a multiwavelength campaign on the TeV γ-ray blazar Mrk 421 performed during 2002 December and 2003 January. These target of opportunity observations were initiated by the detection of X-ray and TeV γ-ray flares with the All Sky Monitor (ASM) on board the Rossi X-Ray Timing Explorer (RXTE) and the 10 m Whipple γ-ray telescope. The campaign included observational coverage in the radio (University of Michigan Radio Astronomy Observatory), optical (Boltwood, La Palma KVA 0.6 m; WIYN 0.9 m), X-ray (RXTE pointed telescopes), and TeV γ-ray (Whipple and HEGRA) bands. At TeV energies, the observations revealed several flares …

Reflection Of A Wave Off A Surface, Brendan Guilfoyle, Wilhelm Klingenberg

Preprints

Recent advances in twistor theory are applied to geometric optics in R 3 . The general formulae for reflection of a wavefront in a surface are derived and in three special cases explicit descriptions are provided: when the reflecting surface is a plane, when the incoming wave is a plane and when the incoming wave is spherical. In each case particular examples are computed exactly and the results plotted to illustrate the outgoing wavefront.

B And I-Band Optical Micro-Variability Observations Of The Bl Lac Objects S5 2007+777 And 3c 371, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

We have observed S5 2007+777 and 3C 371 in the B and I bands for 13 and 8 nights, respectively, during various observing runs in 2001, 2002 and 2004. The observations resulted in almost evenly sampled light curves, h long. We do not detect any flares within the observed light curves, but we do observe small amplitude, significant variations, in both bands, on time scales of hours and days. The average variability amplitude on time scales of minutes/hours is ~2.5% and ~% in the case of S5 2007+777 and 3C 371, respectively. The average amplitudes increase to % and %, …

On Hamilton’S Characteristic Functions For Reflection, Brendan Guilfoyle, Wilhelm Klingenberg

Publications

We review the complex differential geometry of the space of oriented affine lines in R3 and give a description of Hamilton’s characteristic functions for reflection in an oriented C1 surface in terms of this geometry.

Iso Observations Of The Interacting Galaxy Markarian 297 - With The Powerful Supernova Remnant 1982aa, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

Markarian (Mkn) 297 is a complex system comprised of two interacting galaxies that has been modelled with a variety of scenarios. Observations of this system were made with the Infrared Space Observatory (ISO) using the ISOCAM, ISOPHOT and LWS instruments. ISOCAM maps at 6.7 µm, 7.7 µm, 12 µm and 14.3 µm are presented which, together with PHT-S spectrometry of the central interacting region, probe the dust obscured star formation and the properties of the organic dust. The ISOCAM observations reveal that the strongest emission in the four bands is at a location completely unremarkable at visible and near-IR (e.g. …

The Webt Campaign To Observe Ao 0235+16 In The 2003-2004 Observing Season - Results From Radio-To-Optical Monitoring And Xmm-Newton Observations, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

A multiwavelength campaign to observe the BL Lac object AO 0235+16 () was set up by the Whole Earth Blazar Telescope (WEBT) collaboration during the observing seasons 2003–2004 and 2004–2005, involving radio, near-IR and optical photometric monitoring, VLBA monitoring, optical spectral monitoring, and three pointings by the XMM-Newton satellite. Here we report on the results of the first season, which involved the participation of 24 optical and near-IR telescopes and 4 radio telescopes, as well as the first XMM-Newton pointing, which occurred on January 18–19, 2004. Unpublished data from previous epochs were also collected (from 5 optical-NIR and 3 radio …

A Multiwavelength View Of The Tev Blazar Markarian 421: Correlated Variability, Flaring, And Spectral Evolution, P. T. Reynolds, Veritas

Physical Sciences Publications

We report results from an intensive multiwavelength monitoring campaign on the TeV blazar Mrk 421 over the period of 2003-2004. The source was observed simultaneously at TeV energies with the Whipple 10 m telescope and at X-ray energies with the Rossi X-Ray Timing Explorer (RXTE) during each clear night within the Whipple observing windows. Supporting observations were also frequently carried out at optical and radio wavelengths to provide simultaneous or contemporaneous coverages. The large amount of simultaneous data has allowed us to examine the variability of Mrk 421 in detail, including cross-band correlation and broadband spectral variability, over a wide …

A Survey Of Unidentified Egret Sources At Very High Energies, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The Whipple Observatory 10 m γ-ray telescope has been used to survey the error boxes of EGRET unidentified sources in an attempt to find counterparts at energies of 350 GeV and above. Twenty-one unidentified sources detected by EGRET (more than 10% of the total number) have been included in this survey. In no case is a statistically significant signal found in the EGRET error box, which implies that, at least for this sample, the γ-ray spectra of these sources steepen between 100 MeV and 350 GeV. For each EGRET source location, we list candidate associations and derive upper limits on …

A Structure Theorem For Stationary Perfect Fluids, Brendan Guilfoyle

Preprints

It is proven that, under mild physical assumptions, an isolated stationary relativistic perfect fluid consists of a finite number of cells fibred by invariant annuli or invariant tori. For axially symmetric circular flows it is shown that the fluid consists of cells fibred by rigidly rotating annuli or tori.

Level Sets Of Functions And Symmetry Sets Of Surface Sections, André Diatta, Peter Giblin, Brendan Guilfoyle, Wilhelm Klingenberg

Conference Papers

We prove that the level sets of a real C s function of two variables near a non-degenerate critical point are of class C [s/2] and apply this to the study of planar sections of surfaces close to the singular section by the tangent plane at an elliptic or hyperbolic point, and in particular at an umbilic point. We go on to use the results to study symmetry sets of the planar sections. We also analyse one of the cases coming from a degenerate critical point, corresponding to an elliptic cusp of Gauss on a surface, where the …

The Casimir Effect Between Non-Parallel Plates By Geometric Optics, Brendan Guilfoyle, Wilhelm Klingenberg, Siddhartha Sen

Preprints

The first two authors have developed a technique which uses the complex geometry of the space of oriented affine lines in ℝ3 to describe the reflection of rays off a surface. This can be viewed as a parametric approach to geometric optics which has many possible applications. Recently, Jaffe and Scardicchio have developed a geometric optics approximation to the Casimir effect and the main purpose of this paper is to show that the quantities involved can be easily computed by this complex formalism. To illustrate this, we determine explicitly and in closed form the geometric optics approximation of the Casimir …

Generalised Surfaces In ℝ³, Brendan Guilfoyle, Wilhelm Klingenberg

Publications

The correspondence between 2-parameter families of oriented lines in ℝ³ and surfaces in Tℙ¹ is studied, and the geometric properties of the lines are related to the complex geometry of the surface. Congruences generated by global sections of Tℙ¹ are investigated, and a number of theorems are proven that generalise results for closed convex surfaces in ℝ³.

A Search For Tev Gamma-Ray Emission From High-Peaked Flat-Spectrum Radio Quasars Using The Whipple Air Cerenkov Telescope, P. T. Reynolds, Et. Al.

Physical Sciences Publications

Blazars have traditionally been separated into two broad categories based on their optical emission characteristics. Blazars with faint or no emission lines are referred to as BL Lacertae objects (BL Lacs), and blazars with prominent, broad emission lines are commonly referred to as flat-spectrum radio quasars (FSRQs). The spectral energy distribution of FSRQs has generally been thought of as being more akin to the low-peaked BL Lacs, which exhibit a peak in the infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs), which exhibit a peak in UV/X-ray region of the spectrum. All blazars that are currently …

Tev Gamma-Ray Observations Of The Galactic Center, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report a possible detection of TeV gamma rays from the Galactic center by the Whipple 10 m gamma-ray telescope. Twenty-six hours of data were taken over an extended period from 1995 through 2003 resulting in a total significance of 3.7 σ. The measured excess corresponds to an integral flux of 1.6 × 10-8 ± 0.5 × 10-8 (stat) ± 0.3 × 10-8 (sys) photons m-2 s-1 above an energy of 2.8 TeV, roughly 40% of the flux from the Crab Nebula at this energy. The 95% confidence region has an angular extent of about 15' and includes the position …

Xmm-Newton Observations Of The Bl Lac Ms 0205.7+3509: A Dense, Low-Metallicity Absorber, Niall Smith, Et. Al.

Blackrock Castle Observatory Publications

The high-frequency-peaked BL Lac, MS 0205.7+3509 was observed twice with XMM-Newton. Both X-ray spectra are synchrotron-dominated, with mean 0.2–10 keV fluxes of and  erg cm^-2 s^-1. The X-ray spectra are well fit by a power-law with absorption above the Galactic value, however no absorption edges are detected, implying a low metallicity absorber () or an absorber with redshift above one (best-fit for an absorber with solar abundances). In either case the absorbing column density must be  cm^-2. A new optical spectrum is presented, with a absorption doublet detected at , but no other significant …

Constraints On The Very High Energy Emission From Bl Lacertae Objects, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present results from observations of 29 BL Lacertae objects, taken with the Whipple Observatory 10 m gamma-ray telescope between 1995 and 2000. The observed objects are mostly at low redshift (z < 0.2), but observations of objects of up to z = 0.444 are also reported. Five of the objects are EGRET sources and two are unconfirmed TeV sources. Three of the confirmed sources of extragalactic TeV gamma rays were originally observed as part of this survey and have been reported elsewhere. No significant excesses are detected from any of the other objects observed, on timescales of days, months, or years. We report 99.9% confidence level flux upper limits for the objects for each observing season. The flux upper limits are typically 20% of the Crab flux, although for some sources, limits as sensitive as 6% of the Crab flux were derived. The results are consistent with the synchrotron self-Compton model predictions considered in this work.

Observation Of M87 At 400 Gev With The Whipple 10 Meter Telescope, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present results from observations taken with the Whipple 10 m very high energy γ-ray telescope with maximal sensitivity at 400 GeV during 39 hr between 2000 and 2003 in the direction of the giant radio galaxy M87. Using the entire data set, we derive a 99% confidence level upper limit on the flux of γ-ray emission above 400 GeV from M87 to be ≤6.9 × 10-12 cm-2 s-1. This suggests variability at the 90% confidence level when compared to the flux measured by the HEGRA collaboration in 1999 if the differential spectrum is steeper than a power law of …

On The Space Of Oriented Affine Lines In R-3, Brendan Guilfoyle, Wilhelm Klingenberg

Preprints

We introduce a local coordinate description for the correspondence between the space of oriented affine lines in Euclidean R 3 and the tangent bundle to the 2-sphere. These can be utilised to give canonical coordinates on surfaces in R 3 , as we illustrate with a number of explicit examples

Search For High-Energy Gamma Rays From An X-Ray-Selected Blazar Sample, P. T. Reynolds, Et. Al.

Physical Sciences Publications

Our understanding of blazars has been greatly increased in recent years by extensive multiwavelength observations, particularly in the radio, X-ray, and gamma-ray regions. Over the past decade the Whipple 10 m telescope has contributed to this with the detection of five BL Lacertae objects at very high gamma-ray energies. The combination of multiwavelength data has shown that blazars follow a well-defined sequence in terms of their broadband spectral properties. Together with providing constraints on emission models, this information has yielded a means by which potential sources of TeV emission may be identified and predictions made as to their possible gamma-ray …

Search For Tev Emissions From Pulsars In Binary Systems, P. T. Reynolds, Et. Al.

Physical Sciences Publications

A survey of binary systems containing pulsars was conducted, with the intention of detecting Galactic sources of very high energy γ-ray emission. Observations were carried out with the Whipple 10 m imaging atmospheric Cerenkov telescope. Standard analysis techniques were applied to these sources to search for steady, unpulsed emission. Periodic tests were also performed to search for emission correlated with both the orbital and spin phases, where appropriate. Analyses indicate that the binaries in this study do not emit detectable levels of very high energy photons within the sensitivity of our instrument. The flux upper limits presented here fail to …

The Tev Spectrum Of H1426+428, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The BL Lac object H1426+428 was recently detected as a high-energy γ-ray source by the VERITAS collaboration (Horan et al.). We have reanalyzed the 2001 portion of the data used in the detection in order to examine the spectrum of H1426+428 above 250 GeV. We find that the time-averaged spectrum agrees with a power law of the shape

The statistical evidence from our data for emission above 2.5 TeV is 2.6 σ. At the 95% confidence level, the integral flux of H1426+428 above 2.5 TeV is larger than 3% of the corresponding flux from the Crab Nebula. The spectrum is …

Discovery Of Spectral Variability Of Markarian 421 At Tev Energies, P. T. Reynolds, Et. Al.

Physical Sciences Publications

The detection of spectral variability of the γ-ray blazar Mrk 421 at TeV energies is reported. Observations with the Whipple Observatory 10 m γ-ray telescope taken in 2000/2001 revealed exceptionally strong and long-lasting flaring activity. Flaring levels of 0.4-13 times that of the Crab Nebula flux provided sufficient statistics for a detailed study of the energy spectrum between 380 GeV and 8.2 TeV as a function of the flux level. These spectra are well described by a power law with an exponential cutoff: dN/dE ∝ E-αeimg1.gif m-2 s-1 TeV-1. There is no evidence for variation in the cutoff energy with …

The Local Moduli Of Sasakian 3-Manifolds, Brendan Guilfoyle

Publications

The Newman-Penrose-Perjes formalism is applied to Sasakian 3-manifolds and the local form of the metric and contact structure is presented. The local moduli space can be parameterised by a single function of two variables and it is shown that, given any smooth function of two variables, there exists locally a Sasakian structure with scalar curvature equal to this function. The case where the scalar curvature is constant (η-Einstein Sasakian metrics) is completely solved locally. The resulting Sasakian manifolds include S 3, Nil, and SL˜ 2 (ℝ), as well as the Berger spheres. It is also shown that a conformally flat …

Multiwavelength Observations Of A Tev-Flare From W Comae, P. T. Reynolds, Veritas, Agile

Physical Sciences Publications

No abstract provided.

Interior Weyl-Type Solutions To The Einstein-Maxwell Field Equations, Brendan Guilfoyle

Preprints

Static solutions of the electro-gravitational field equations exhibiting a functional relationship between the electric and gravitational potentials are studied. General results for these metrics are presented which extend previous work of Majumdar. In particular, it is shown that for any solution of the field equations exhibiting such a Weyl-type relationship, there exists a relationship between the matter density, the electric field density and the charge density. It is also found that the Majumdar condition can hold for a bounded perfect fluid only if the matter pressure vanishes (that is, charged dust). By restricting to spherically symmetric distributions of charged matter, …

Weyl-Type Fields With Geodesic Lines Of Force, Brendan Guilfoyle

Publications

The static electrogravitational equations are studied and it is shown that an aligned type D metric which has a Weyl-type relationship between the gravitational and electric potential has shearfree geodesic lines of force. All such fields are then found and turn out to be the fields of a charged sphere, charged infinite rod and charged infinite plate. A further solution is also found with shearing geodesic lines of force. This new solution can have m > |e| or m < |e|, but cannot be in the Majumdar-Papapetrou class (in which m = |e|). It is algebraically general and has flat equipotential surfaces.

Yang's Gravitational Theory, Brendan Guilfoyle, Brien C. Nolan

Publications

Yang's pure space equations generalize Einstein's gravitational equations, while coming from gauge theory. We study these equations from a number of vantage points: summarizing the work done previously, comparing them with the Einstein equations and investigating their properties. In particular, the initial value problem is discussed and a number of results are presented for these equations with common energy-momentum tensors.