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MULTIWAVELENGTH OBSERVATIONS OF LS I +61° 303 WITH VERITAS, SWIFT, AND RXTE |
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Science Publications
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Written by V. A. Acciari et al
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Saturday, 01 August 2009 |
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The Astrophysical Journal Letters, Volume 700, Issue 2, pp. 1034-1041 (2009). arXiv:0904.4422 We present results from a long-term monitoring campaign on the TeV binary LSI +61° 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8σ (2006/2007) and 7.3σ (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6σ significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 ×10–11 erg cm–2 s–1 over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands. |
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Last Updated ( Tuesday, 06 October 2009 )
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Search for TeV Emission from Geminga by VERITAS |
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Conference Proceedings
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Written by Gary Finnegan for the VERITAS Collaboration
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Thursday, 30 July 2009 |
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arXiv:0907.5237 The Geminga gamma ray source was first detected by SAS-2 and COS-B, and has been identified as a radio-quiet pulsar associated with a 300,000 year old supernova remnant. Geminga is one of the brightest GeV sources and was also detected by Milagro at energies greater than 20 TeV. During 2007 VERITAS performed observations to search for TeV gamma ray emission from the Geminga pulsar and the region near Geminga. In this paper, we describe these measurements and new analysis of these observations. |
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Simultaneous Observations of Flaring Gamma-ray Blazar 3C 66A with Fermi-LAT and VERITAS |
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Conference Proceedings
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Written by Luis C. Reyes, for the Fermi LAT collaboration, the VERITAS collaboration
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Wednesday, 29 July 2009 |
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arXiv:0907.5175 The intermediate-frequency-peaked BL Lac object 3C 66A was detected in a flaring state by the Fermi-LAT and VERITAS observatories in October 2008. These data and follow-up observations at other wavelengths create a rich sample of light curves and a constraining spectral energy distribution (SED). This is the first time that simultaneous observations at GeV and TeV energies were obtained for a flaring blazar. Results from these joint Fermi-LAT and VERITAS observations are presented in this conference proceeding. |
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Observations of Supernova Remnants and Pulsar Wind Nebulae: A VERITAS Key Science Project |
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Conference Proceedings
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Written by Brian Humensky, for the VERITAS Collaboration
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Tuesday, 28 July 2009 |
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arXiv:0907.5020 The study of supernova remnants and pulsar wind nebulae was one of the Key Science Projects for the first two years of VERITAS observations. VERITAS is an array of four imaging Cherenkov telescopes located at the Whipple Observatory in southern Arizona. Supernova remnants are widely considered to be the strongest candidate for the source of cosmic rays below the knee at around 10^15 eV. Pulsar wind nebulae are synchrotron nebulae powered by the spin-down of energetic young pulsars, and comprise one of the most populous very-high-energy gamma-ray source classes. This poster will summarize the results of this observation program. |
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Last Updated ( Friday, 31 July 2009 )
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VERITAS Observations of Globular Clusters |
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Conference Proceedings
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Written by Michael McCutcheon, for the VERITAS Collaboration
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Tuesday, 28 July 2009 |
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arXiv:0907.4974 It has been postulated that globular clusters could be sources of Very-High Energy (VHE) gamma rays, powered by milli-second pulsars. This could be due to cumulative direct emission or to plerion-type emission driven by colliding winds. In particular the southern hemisphere globular cluster 47 Tuc has been singled out as a potential source in both models. In light of the recent detection by the Fermi Gamma-ray Space Telescope (FGST) of 47 Tuc, the first detection of any globular cluster as a gamma-ray source, we present the results of observations of northern hemisphere globular clusters by VERITAS. Three globular clusters have been observed: M15, M13 and M5. Of these, M15 and M13 have been explicitly proposed as VHE gamma-ray sources and M5 possess similarities with them. |
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