Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 59, Number 11
Friday–Saturday, October 17–18, 2014; Orem, Utah
Session I5: High Energy Astrophysics |
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Chair: Mark Boslough, Sandia National Laboratories Room: Science Building 260 |
Saturday, October 18, 2014 10:15AM - 10:27AM |
I5.00001: Using Direct Cherenkov light to detect Ultra-Heavy cosmic rays David Kieda The Direct Cherenkov (DC) Technique has been recently used to allow Imagining Atmospheric Cherenkov Telescopes (IACTs) such as HESS and VERITAS to cleanly identify the primary iron component of the cosmic ray flux near the knee of the cosmic ray spectrum. The DC Technique allows measurement of primary charge with a resolution of $\Delta $Z/Z $\approx $ 10{\%} for nuclei heavier than carbon, with essentially no dependence on the assumed nuclear interaction model. In this talk I will describe the possibility of using the DC technique to detect Ultra-Heavy (UH, Z $\gg$ 26) cosmic rays at energies approaching 1 PeV (10$^{\mathrm{15}}$ eV). I will also describe what can be learned about the origin and propagation of cosmic rays through the observation of PeV UH cosmic rays. [Preview Abstract] |
Saturday, October 18, 2014 10:27AM - 10:39AM |
I5.00002: Performance of VERITAS Observatory Payel Kar VERITAS is an array of four Imaging Atmospheric Cherenkov Telescopes (IACT) looking at the Gamma ray sky. Located at the Fred Lawrence Whipple Observatory in Southern Arizona, it covers the energy range from 100 GeV to 30 TeV. All four telescope operations began in March 2007. Tel 1 was moved to a different position within the array to improve sensitivity. A major hardware upgrade was completed in Summer 2012 to the camera and pattern triggering systems resulting in a 50\% increase in photon detection efficiency and a 30\% reduction in triggering threshold under dark sky conditions. Presented here is the performance of VERITAS, determined with instrument response functions from simulations, which utilize long-term calibration measurements. A comparison of pre to post-upgrade Crab observations provides the most direct method for quantifying the improvement in the performance with better noise reduction, faster source detection and lowered energy threshold. One of the sources VERITAS sees is LS I 61+303 which is a High Mass X-Ray Binary (HMXB), a member from a sparsely populated catalogue of TeV Binaries. Included is an overview of this source, 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. [Preview Abstract] |
Saturday, October 18, 2014 10:39AM - 10:51AM |
I5.00003: VERITAS Extended Source Detections Andrew Flinders VERITAS is an array of four Imaging Air Cherenkov Telescopes located in southern Arizona. The VERITAS array has been successful in detecting a wide variety of sources of Very High Energy ($\sim$ 100 GeV - $\sim$ 30TeV) radiation. Several of the sources detected by VERITAS have exhibited extended emission. I will discuss two of these extended sources. The first is MGRO J2019$+$37, which has been resolved into two VERITAS sources. The second is TeV J2032$+$4130, a widely studied source in many wavelengths. For each source I will present the results of the VERITAS observations and the impact these observations have had on our understanding of those sources. [Preview Abstract] |
Saturday, October 18, 2014 10:51AM - 11:03AM |
I5.00004: Search For Astrophysical Jets Using VERITAS Data Of Markarian 421 Brianna Thorpe, David Kieda, Andy Smith The signature of the emergence of a jet in a galactic object could manifest itself by the change in position of the object. Observations of such an effect would require clear evidence that the telescope pointing had not changed during the time that the change was observed. This can be studied through detailed observations of the location of bright extragalactic gamma ray sources such as Markarian 421. I helped to provide a lower bound on the probability of the emergence of a jet in a galactic object by examining systematic shifts in observations of Markarian 421. [Preview Abstract] |
Saturday, October 18, 2014 11:03AM - 11:15AM |
I5.00005: TeV Astronomy with HAWC-VERITAS synergy Anushka Abeysekara Very high energy astrophysics is on the verge of entering a golden era. The most sensitive TeV gamma-ray survey experiment, High Altitude Water Cherenkov (HAWC), already started surveying for TeV emission with the partially built detector. The galactic plane already became visible to the partially built HAWC experiment. In the near future HAWC data set will be able to produce an unbiased survey of the TeV sky. In the same time the major upgrade in Summer 2012 done in the Very Energetic Radiation Imaging Telescope Array System (VERITAS) gamma-ray observatory gives an unprecedented sensitivity, energy resolution and angular resolution for pointed observations. However, pointed VERITAS observations are inherently limited by its small field of view, $3.5^{\circ}$. Therefore, a synergy program between HAWC and VERITAS collaborations is the key aspect of discovering new TeV sources and measure their properties in detail. Science capabilities and the current status of the HAWC-VERITAS synergy program will be presented. [Preview Abstract] |
Saturday, October 18, 2014 11:15AM - 11:27AM |
I5.00006: The High Altitude Water Cherenkov (HAWC) observatory, Early results and future potential Michael Newbold The High Altitude Water Cherenkov (HAWC) observatory measures the flux of gamma and cosmic rays impinging on the Earth's atmosphere. The observatory is located on Sierra Negra Mountain in Mexico at an elevation of 4100 m, enabling the measurement of extensive air showers initiated by gamma and cosmic rays with energies in the range from several hundred GeV to several hundred TeV. The completed detector will consist of 300 closely spaced water tanks, each instrumented with four photomultiplier tubes to provide timing and charge information. HAWC, with a wide field of view and a high duty cycle, is optimal to survey a large fraction of the sky and study transient and steady emission from both galactic and extragalactic sources of gamma rays. This high discovery potential of HAWC will provide the large data set necessary for studies of basic physics. In particular, a sufficient quantity of blazars, will allow for constraints on the opacity due to pair-production and in turn, an upper limit on the Extra-Galactic Background Light (EBL) population. Early results from the observatory will be presented along with plans for future analysis. [Preview Abstract] |
Saturday, October 18, 2014 11:27AM - 11:39AM |
I5.00007: HAWC Observation of Small-Scale Cosmic-Ray Anisotropy Ahron Barber The HAWC (High Altitude Water Cherenkov) Observatory, located on Sierra Negra in Mexico at 4100m asl, indirectly detects gamma and cosmic rays at energies between around 100 GeV to 100 TeV. With the data collected over the first 8 months of operation of the partially completed detector, HAWC has observed three distinct regions of excess cosmic-ray flux. These regions are observed to be on angular scales near 10 degrees. In this talk, I will describe the anisotropy characteristics observed by HAWC, and compare to the cosmic-ray anisotropy observed by other detectors. [Preview Abstract] |
Saturday, October 18, 2014 11:39AM - 11:51AM |
I5.00008: EUSO balloon campaign Johannes Eser, Lawrence Wiencke The Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) is being designed to observe extensive air showers caused by extreme energy cosmic rays striking the atmosphere. The EUSO-Balloon prototype instrument, was flown as the payload of a stratospheric balloon from the Timmins Stratospheric Balloon Facility in Ontario, Canada at the end of August 2014. The campaign included an under flight of the balloon by a helicopter that carried two graduate students and three light sources including a UV laser, a UV-LED, a Xe-Flash lamp. We present a preliminary report of the Timmins campaign. [Preview Abstract] |
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