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Detection of Extended VHE Gamma Ray Emission from G106.3+2.7 with VERITAS
Get PDFWe report the detection of very-high-energy (VHE) gamma-ray emission from supernova remnant (SNR) G106.3+2.7. Observations performed in 2008 with the VERITAS atmospheric Cherenkov gamma-ray telescope resolve extended emission overlapping the elongated radio SNR. The 7.3σ (pre-trials) detection has a full angular extent of roughly 06 by 04. Most notably, the centroid of the VHE emission is centered near the peak of the coincident 12CO (J = 1-0) emission, 04 away from the pulsar PSR J2229+6114, situated at the northern end of the SNR. Evidently the current-epoch particles from the pulsar wind nebula are not participating in the gamma-ray production. The VHE energy spectrum measured with VERITAS is well characterized by a power law dN/dE = N 0(E/3 TeV)–Γ with a differential index of Γ = 2.29 ± 0.33stat ± 0.30sys and a flux of N 0 = (1.15 ± 0.27stat ± 0.35sys) × 10–13 cm–2 s–1 TeV–1. The integral flux above 1 TeV corresponds to ~5 percent of the steady Crab Nebula emission above the same energy. We describe the observations and analysis of the object and briefly discuss the implications of the detection in a multiwavelength context
Observation of extended very high energy emission from the supernova remnant ic 443 with veritas
Get PDFWe present evidence that the very high energy (VHE, E \u3e 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hr during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (σ) before trials and 7.5σ after trials in a point-source search. The emission is centered at 6h16m51s + 22°30\u2711\u27\u27 (J2000) ±003stat ± 008sys, with an intrinsic extension of 016 ± 003stat ± 004sys. The VHE spectrum is well fit by a power law (dN/dE = N 0 × (E/TeV)–Γ) with a photon index of 2.99 ± 0.38stat ± 0.3sys and an integral flux above 300 GeV of (4.63 ± 0.90stat ± 0.93sys) × 10–12 cm–2 s–1. These results are discussed in the context of existing models for gamma-ray production in IC 443
Gamma-Ray Observations Of The Be/Pulsar Binary 1a 0535+262 During A Giant X-Ray Outburst
No full textDifferences in Exchange Situations in Fast Moving Consumer Goods\u27 Markets
Get PDFThis paper explores the perceptions and the behaviour of consumers in Fast Moving Consumer Goods’ (FMCG) markets, with the objective of determining the nature of exchange in these markets. Adopting a qualitative approach to the research, ten focus groups were conducted among Irish consumers in FMCG markets. Emerging from the research are four dominant exchange situations that exist in FMCG markets. These exchange situations are classified as inconsistent transaction exchanges, distant committed exchanges, opportunistic interactive exchanges and reciprocal interactive exchanges. The dominant conclusion of this paper is that marketing strategies appropriate to these exchange situations need to be developed, where the focus of the strategies is on developing and nurturing bonds as they develop between consumers and brands, and encouraging consumers to engage in interactive behaviour with companies where it emerges that it is appropriate to do so. It is concluded that the mass adoption of relationship marketing strategies should decrease, and that marketing strategies suited to the nature of exchange as it exists with consumers should be developed and appropriately targeted
The Fast Recovery Dynamics Of A Quantum Dot Semiconductor Optical Amplifier
Get PDFWe consider a rate equation model of a quantum dot semiconductor optical amplifier that takes into account carrier capture, escape, and Pauli blocking processes. We evaluate possible differences between phonon-assisted or Auger processes being dominant for recovery. An analytical solution which corresponds to phonon-assisted interaction is then used to accurately fit experimental recovery curves and allows an estimation of both the carrier capture and escape rates
Simultaneous Multiwavelength Observations Of Markarian 421 During Outburst
Get PDFWe report on the results of two coordinated multiwavelength campaigns that focused on the blazar Markarian 421 during its 2006 and 2008 outbursts. These campaigns obtained UV and X-ray data using the XMM-Newton satellite, while the gamma-ray data were obtained utilizing three imaging atmospheric Cerenkov telescopes, the Whipple 10 m telescope and VERITAS, both based in Arizona, as well as the MAGIC telescope, based on La Palma in the Canary Islands. The coordinated effort between the gamma-ray groups allowed for truly simultaneous data in UV/X-ray/gamma-ray wavelengths during a significant portion of the XMM-Newton observations. This simultaneous coverage allowed for a reliable search for correlations between UV, X-ray, and gamma-ray variability over the course of the observations. Investigations of spectral hysteresis and modeling of the spectral energy distributions are also presented
Veritas Observations Of The Bl Lac Object 1es 1218+304
Get PDFThe VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4σ) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ~160 GeV and ~1.8 TeV is well described by a power law with an index of Γ = 3.08 ± 0.34stat ± 0.2sys. The integral flux is Φ(E\u3e200GeV) = (12.2 ± 2.6) × 10–12 cm-2 s–1, which corresponds to ~6% of that of the Crab Nebula. The light curve does not show any evidence for very high energy flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared, we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Γ = 2.32 ± 0.37stat. When including constraints from the spectra of 1ES 1101-232 and 1ES 0229+200, the spectrum of 1ES 1218+304 is likely to be harder than Γ = 1.86 ± 0.37stat
VERITAS Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C 66A
Get PDFThe intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007-2008 in VHE (very high energy; E \u3e 100 GeV) γ rays with the VERITAS stereoscopic array of imaging atmospheric Cherenkov telescopes. An excess of 1791 events is detected, corresponding to a significance of 21.2 standard deviations (σ), in these observations (32.8 hr live time). The observed integral flux above 200 GeV is 6% of the Crab Nebula\u27s flux and shows evidence for variability on the timescale of days. The measured energy spectrum is characterized by a soft power law with photon index Γ = 4.1 ± 0.4stat ± 0.6sys. The radio galaxy 3C 66B is excluded as a possible source of the VHE emission
