Search

Your search keyword '"Gibbs K"' showing total 683 results
Start Over Author "Gibbs K"

Refine your results

more »

more »

more »

more »

more »
683 results on '"Gibbs K"'

3. Real-time Prospective Classification of Biologic Sub-phenotypes in Severe Acute Respiratory Failure: An Interim Report on the SPARC Study

Author

Files, D.C., primary, Gibbs, K., additional, Matthay, M.A., additional, Calfee, C.S., additional, Youssef, F.A., additional, Liu, K., additional, Russell, D.W., additional, Meyer, N.J., additional, Aggarwal, N.R., additional, Martin, T.R., additional, Mabrey, L., additional, Krall, J.T.W., additional, Thomas, K.W., additional, Henderson, P., additional, and Esserman, L., additional

Published
2024
Full Text
View/download PDF

4. Optimal Mode of Mechanical Ventilation for Adults in Shock: A Secondary Analysis of the Mode of Ventilation During Critical Illness Trial

Author

Talbot, E., primary, Lloyd, B., additional, Wang, L., additional, Shotwell, M., additional, Qian, E.T., additional, Muhs, A., additional, Richardson, R.K., additional, Rooks, J.C., additional, Hennings-Williams, V., additional, Sandoval, C.E., additional, Richardson, W.D., additional, Morgan, T., additional, Thompson, A.N., additional, Hastings, P.G., additional, Ring, T.P., additional, Stollings, J.L., additional, Krasinski, D.J., additional, Decoursey, B., additional, Gibbs, K., additional, Self, W., additional, Mixon, A.S., additional, Rice, T.W., additional, Casey, J.D., additional, Semler, M.W., additional, and Seitz, K.P., additional

Published
2024
Full Text
View/download PDF

6. Noninvasive Ventilation for Preoxygenation during Emergency Intubation.

Author

Gibbs, K. W., Semler, M. W., Driver, B. E., Seitz, K. P., Stempek, S. B., Taylor, C., Resnick-Ault, D., White, H. D., Gandotra, S., Doerschug, K. C., Mohamed, A., Prekker, M. E., Khan, A., Gaillard, J. P., Andrea, L., Aggarwal, N. R., Brainard, J. C., Barnett, L. A. H., Halliday, S. J., and Blinder, V.

Subjects
*NONINVASIVE ventilation, *OXYGEN saturation, *INTUBATION, *TRACHEA intubation, *OXYGEN masks
Abstract

BACKGROUND Among critically ill adults undergoing tracheal intubation, hypoxemia increases the risk of cardiac arrest and death. The effect of preoxygenation with noninvasive ventilation, as compared with preoxygenation with an oxygen mask, on the incidence of hypoxemia during tracheal intubation is uncertain. METHODS In a multicenter, randomized trial conducted at 24 emergency departments and intensive care units in the United States, we randomly assigned critically ill adults (age, ≥18 years) undergoing tracheal intubation to receive preoxygenation with either noninvasive ventilation or an oxygen mask. The primary outcome was hypoxemia during intubation, defined by an oxygen saturation of less than 85% during the interval between induction of anesthesia and 2 minutes after tracheal intubation. RESULTS Among the 1301 patients enrolled, hypoxemia occurred in 57 of 624 patients (9.1%) in the noninvasive-ventilation group and in 118 of 637 patients (18.5%) in the oxygen-mask group (difference, -9.4 percentage points; 95% confidence interval [CI], -13.2 to -5.6; P<0.001). Cardiac arrest occurred in 1 patient (0.2%) in the noninvasive-ventilation group and in 7 patients (1.1%) in the oxygen-mask group (difference, -0.9 percentage points; 95% CI, -1.8 to -0.1). Aspiration occurred in 6 patients (0.9%) in the noninvasive-ventilation group and in 9 patients (1.4%) in the oxygen-mask group (difference, -0.4 percentage points; 95% CI, -1.6 to 0.7). CONCLUSIONS Among critically ill adults undergoing tracheal intubation, preoxygenation with noninvasive ventilation resulted in a lower incidence of hypoxemia during intubation than preoxygenation with an oxygen mask. (Funded by the U.S. Department of Defense; PREOXI ClinicalTrials.gov number, NCT05267652.) [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

8. Modifying axonal transport as a therapeutic strategy for Amyotrophic Lateral Sclerosis

Author

Gibbs, K. L. and Schiavo, G.

Subjects
612.8
Abstract

Deficits in retrograde axonal transport have been described at a presymptomatic stage in the SOD1G93A mouse model of ALS. The early appearance of transport defects suggests that they may play an important role in disease pathogenesis. However, the causative role of axonal transport deficits in ALS motor neuron degeneration has not yet been demonstrated directly. The goal of my PhD project was to identify pharmacological enhancers of retrograde axonal transport that could be used to prove conclusively whether axonal transport defects play a significant role in ALS pathogenesis. To this aim, I developed and performed a microscopy-based screen for the identification of pharmacological enhancers of retrograde axonal transport in motor neurons. I was able to demonstrate that the accumulation of α-p75NTR and HCT in the cell body of mouse ES-derived motor neurons acts as a sensitive read-out of retrograde axonal transport efficiency and using this assay, I identified and validated two compounds (A1 and E4) that were able to accelerate retrograde axonal transport in motor neurons. Compound A1 was revealed to be an inhibitor of p38 MAPK. Inhibition of p38 MAPK was found to correct deficits in retrograde axonal transport in SOD1G93A motor neurons both in vitro and in vivo. Using genetic and pharmacological approaches, I was able to demonstrate that p38 MAPKα is responsible for the transport deficits observed. Compound E4 was revealed to be an inhibitor of the IGF1 receptor (IGF1R). It was found to accelerate retrograde axonal transport in both wild type and SOD1G93A motor neurons, but had no effect on anterograde transport speeds. In conclusion, this thesis work has identified inhibitors of p38 MAPK and IGF1R as novel modifiers of retrograde axonal transport and demonstrated that inhibitors of p38 MAPKα can be used to determine the role of axonal transport defects in ALS pathogenesis.

Published
2015

9. Observation of Markarian 421 in TeV gamma rays over a 14-year time span

Author

Acciari, V. A., Arlen, T., Aune, T., Benbow, W., Bird, R., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Perez, I. de la Calle, Carter-Lewis, D. A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Duke, C., Dumm, J., Falcone, A., Federici, S., Fegan, D. J., Fegan, S. J., Finley, J. P., Finnegan, G., Fortson, L., Gaidos, J., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Horan, D., Humensky, T. B., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., McEnery, J. E., Madhavan, A. S., Moriarty, P., Nelson, T., de Bhróithe, A. O'Faoláin, Ong, R. A., Orr, M., Otte, A. N., Perkins, J. S., Petry, D., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Roache, E., Rovero, A., Schroedter, M., Sembroski, G. H., Smith, A., Telezhinsky, I., Theiling, M., Toner, J., Tyler, J., Varlotta, A., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Welsing, R., Williams, D. A., and Wissel, S.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4 hours of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The time-averaged flux from Markarian 421 over this period was 0.446$\pm$0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units., Comment: 29 pages, 15 figures. Accepted for publication in Astroparticle Physics

Published
2013
Full Text
View/download PDF

10. VERITAS Collaboration Contributions to the 32nd International Cosmic Ray Conference

Author

The VERITAS Collaboration, Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dwarkadas, V. V., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nunez, P. D, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Rovero, A. C., Ruppel, J., Sadun, A. C., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Compilation of papers contributed by the VERITAS Collaboration to the 32nd International Cosmic Ray Conference, held 11-18 August 2011 in Beijing, China., Comment: 1 html page. ICRC 2011, Beijing, China. A full list of authors and collaborating institutions can be found at http://veritas.sao.arizona.edu/conferences/authors?icrc2011

Published
2011

11. VERITAS: Status and Highlights

Author

Holder, J., Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dwarkadas, V. V., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nunez, P. D, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Rovero, A. C., Ruppel, J., Sadun, A. C., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The VERITAS telescope array has been operating smoothly since 2007, and has detected gamma-ray emission above 100 GeV from 40 astrophysical sources. These include blazars, pulsar wind nebulae, supernova remnants, gamma-ray binary systems, a starburst galaxy, a radio galaxy, the Crab pulsar, and gamma-ray sources whose origin remains unidentified. In 2009, the array was reconfigured, greatly improving the sensitivity. We summarize the current status of the observatory, describe some of the scientific highlights since 2009, and outline plans for the future., Comment: Presented at the 32nd ICRC, Beijing, 2011

Published
2011
Full Text
View/download PDF

12. Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar

Author

VERITAS Collaboration, Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nuñez, P., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 Gigaelectronvolts (GeV) with the VERITAS array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 Megaelectronvolts (MeV) and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star., Comment: 17 pages, corresponding authors: Nepomuk Otte nepomuk.otte@gmail.com; Andrew McCann mccann@hep.physics.mcgill.ca; Martin Schroedter schroedter@veritas.sao.arizona.edu

Published
2011
Full Text
View/download PDF

13. The Discovery of gamma-Ray Emission From The Blazar RGB J0710+591

Author

Acciari, V. A., Aliu, E., Arlen, T., Aune, T., Bautista, M., Beilicke, M., Benbow, W., Böttcher, M., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Cui, W., Dickherber, R., Duke, C., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., Lamerato, A., LeBohec, S., Maier, G., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Petry, D., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Roustazadeh, P., Schroedter, M., Sembroski, G. H., Senturk, G. Demet, Smith, A. W., Steele, D., Swordy, S. P., Tešić, G., Theiling, M., Thibadeau, S., Varlotta, A., Vassiliev, V. V., Vincent, S., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., Wood, M., Zitzer, B., Ackermann, M., Ajello, M., Antolini, E., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bouvier, A., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., Carrigan, S., Casandjian, J. M., Cavazzuti, E., Cecchi, C., Çelik, Ö., Charles, E., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cohen-Tanugi, J., Conrad, J., Dermer, C. D., de Palma, F., Silva, E. do Couto e, Drell, P. S., Dubois, R., Dumora, D., Farnier, C., Favuzzi, C., Fegan, S. J., Fortin, P., Frailis, M., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giebels, B., Giglietto, N., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Grove, J. E., Guiriec, S., Hays, E., Horan, D., Hughes, R. E., Jóhannesson, G., Johnson, A. S., Johnson, W. N., Kamae, T., Katagiri, H., Kataoka, J., Knödlseder, J., Kuss, M., Lande, J., Latronico, L., Lee, S. -H., Garde, M. Llena, Longo, F., Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Makeev, A., Mazziotta, M. N., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Nolan, P. L., Norris, J. P., Nuss, E., Ohno, M., Ohsugi, T., Omodei, N., Orlando, E., Ormes, J. F., Paneque, D., Panetta, J. H., Pelassa, V., Pepe, M., Pesce-Rollins, M., Piron, F., Porter, T. A., Rainò, S., Rando, R., Razzano, M., Reimer, A., Reimer, O., Ripken, J., Rodriguez, A. Y., Roth, M., Sadrozinski, H. F. -W., Sanchez, D., Sander, A., Scargle, J. D., Sgrò, C., Siskind, E. J., Smith, P. D., Spandre, G., Spinelli, P., Strickman, M. S., Suson, D. J., Takahashi, H., Tanaka, T., Thayer, J. B., Thayer, J. G., Thompson, D. J., Tibaldo, L., Torres, D. F., Tosti, G., Tramacere, A., Usher, T. L., Vasileiou, V., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Winer, B. L., Wood, K. S., Yang, Z., Ylinen, T., and Ziegler, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The high-frequency-peaked BL Lacertae object RGB J0710+591 was observed in the very high-energy (VHE; E > 100 GeV) wave band by the VERITAS array of atmospheric Cherenkov telescopes. The observations, taken between 2008 December and 2009 March and totaling 22.1 hr, yield the discovery of VHE gamma rays from the source. RGB J0710+591 is detected at a statistical significance of 5.5 standard deviations (5.5{\sigma}) above the background, corresponding to an integral flux of (3.9 +/- 0.8) x 10-12 cm-2 s-1 (3% of the Crab Nebula's flux) above 300 GeV. The observed spectrum can be fit by a power law from 0.31 to 4.6 TeV with a photon spectral index of 2.69 +/- 0.26stat +/- 0.20sys. These data are complemented by contemporaneous multiwavelength data from the Fermi Large Area Telescope, the Swift X-ray Telescope, the Swift Ultra-Violet and Optical Telescope, and the Michigan-Dartmouth-MIT observatory. Modeling the broadband spectral energy distribution (SED) with an equilibrium synchrotron self-Compton model yields a good statistical fit to the data. The addition of an external-Compton component to the model does not improve the fit nor brings the system closer to equipartition. The combined Fermi and VERITAS data constrain the properties of the high-energy emission component of the source over 4 orders of magnitude and give measurements of the rising and falling sections of the SED.

Published
2010
Full Text
View/download PDF

14. Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITAS

Author

The VERITAS Collaboration, Acciari, V. A., Aliu, E., Beilicke, M., Benbow, W., Boltuch, D., Böttcher, M., Bradbury, S. M., Bugaev, V., Byrum, K., Cesarini, A., Ciupik, L., Cogan, P., Cui, W., Dickherber, R., Duke, C., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Guenette, R., Gillanders, G. H., Godambe, S., Grube, J., Hanna, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McArthur, S., McCann, A., Moriarty, P., Nagai, T., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Thibadeau, S., Vassiliev, V. V., Vincent, S., Wakely, S. P., Weekes, T. C., Weinstein, A., Weisgarber, T., and Williams, D. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ~6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ~20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices less than 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical gamma-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios., Comment: 5 pages, 3 figures; Published in The Astrophysical Journal Letters

Published
2010
Full Text
View/download PDF

15. A connection between star formation activity and cosmic rays in the starburst galaxy M 82

Author

Acciari, V. A., Aliu, E., Arlen, T., Aune, T., Bautista, M., Beilicke, M., Benbow, W., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Celik, O., Cesarini, A., Chow, Y. C., Ciupik, L., Cogan, P., Colin, P., Cui, W., Dickherber, R., Duke, C., Fegan, S. J., Finley, J. P., Finnegan, G., Fortin, P., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McArthur, S., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Nagai, T., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Pizlo, F., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Thibadeau, S., Varlotta, A., Vassiliev, V. V., Vincent, S., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., Wood, M., and Zitzer, B.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

Although Galactic cosmic rays (protons and nuclei) are widely believed to be dominantly accelerated by the winds and supernovae of massive stars, definitive evidence of this origin remains elusive nearly a century after their discovery [1]. The active regions of starburst galaxies have exceptionally high rates of star formation, and their large size, more than 50 times the diameter of similar Galactic regions, uniquely enables reliable calorimetric measurements of their potentially high cosmic-ray density [2]. The cosmic rays produced in the formation, life, and death of their massive stars are expected to eventually produce diffuse gamma-ray emission via their interactions with interstellar gas and radiation. M 82, the prototype small starburst galaxy, is predicted to be the brightest starburst galaxy in gamma rays [3, 4]. Here we report the detection of >700 GeV gamma rays from M 82. From these data we determine a cosmic-ray density of 250 eV cm-3 in the starburst core of M 82, or about 500 times the average Galactic density. This result strongly supports that cosmic-ray acceleration is tied to star formation activity, and that supernovae and massive-star winds are the dominant accelerators., Comment: 18 pages, 4 figures; published in Nature; Version is prior to Nature's in-house style editing (differences are minimal)

Published
2009
Full Text
View/download PDF

16. VERITAS Upper Limit on the VHE Emission from the Radio Galaxy NGC 1275

Author

VERITAS Collaboration, Acciari, V. A., Aliu, E., Arlen, T., Aune, T., Bautista, M., Beilicke, M., Benbow, W., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Celik, O., Cesarini, A., Ciupik, L., Cogan, P., Cui, W., Dickherber, R., Duke, C., Fegan, S. J., Finley, J. P., Fortin, P., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Toner, J. A., Varlotta, A., Vassiliev, V. V., Vincent, S., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., Wood, M., Zitzer, B., Kataoka, J., Cavazzuti, E., Cheung, C. C., Lott, B., Thompson, D. J., and Tosti, G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The recent detection by the Fermi gamma-ray space telescope of high-energy gamma-rays from the radio galaxy NGC 1275 makes the observation of the very high energy (VHE: E > 100 GeV) part of its broadband spectrum particularly interesting, especially for the understanding of active galactic nuclei (AGN) with misaligned multi-structured jets. The radio galaxy NGC 1275 was recently observed by VERITAS at energies above 100 GeV for about 8 hours. No VHE gamma-ray emission was detected by VERITAS from NGC 1275. A 99% confidence level upper limit of 2.1% of the Crab Nebula flux level is obtained at the decorrelation energy of approximately 340 GeV, corresponding to 19% of the power-law extrapolation of the Fermi Large Area Telescope (LAT) result., Comment: Accepted for publication in ApJ Letters

Published
2009
Full Text
View/download PDF

17. Multiwavelength observations of a TeV-Flare from W Comae

Author

VERITAS collaboration, Acciari, V. A., Aliu, E., Aune, T., Beilicke, M., Benbow, W., Bottcher, M., Boltuch, D., Buckley, J. H., Bradbury, S. M., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Cogan, P., Cui, W., Dickherber, R., Duke, C., Falcone, A., Finley, J. P., Fortin, P., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Hui, C. M., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McArthur, S., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Sembroski, G. H., Smith, A. W., Steele, D., Theiling, M., Thibadeau, S., Varlotta, A., Vassiliev, V. V., Vincent, S., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., Wood, M., Team, The AGILE, Pian, E., Vercellone, S., Donnarumma, I., D'Ammando, F., Bulgarelli, A., Chen, A. W., Giuliani, A., Longo, F., Pacciani, L., Pucella, G., Vittorini, V., Tavani, M., Argan, A., Barbiellini, G., Caraveo, P., Cattaneo, P. W., Cocco, V., Costa, E., Del Monte, E., De Paris, G., Di Cocco, G., Evangelista, Y., Feroci, M., Fiorini, M., Froysland, T., Frutti, M., Fuschino, F., Galli, M., Gianotti, F., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Marisaldi, M., Mastropietro, M., Mereghetti, S., Morelli, E., Morselli, A., Pellizzoni, A., Perotti, F., Piano, G., Picozza, P., Pilia, M., Porrovecchio, G., Prest, M., Rapisarda, M., Rappoldi, A., Rubini, A., Soffitta, S. Sabatini P., Trifoglio, M., Trois, A., Vallazza, E., Zambra, A., Zanello, D., Pittori, C., Santolamazza, P., Verrecchia, F., Giommi, P., Colafrancesco, S., Salotti, L., Villata, M., Raiteri, C. M., Aller, H. D., Aller, M. F., Arkharov, A. A., Efimova, N. V., Larionov, V. M., Leto, P., Ligustri, R., Lindfors, E., Pasanen, M., Kurtanidze, O. M., Tetradze, S. D., Lahteenmaki, A., Kotiranta, M., Cucchiara, A., Romano, P., Nesci, R., Pursimo, T., Heidt, J., Benitez, E., Hiriart, D., Nilsson, K., Berdyugin, A., Mujica, R., Dultzin, D., Lopez, J. M., Mommert, M., Sorcia, M., and Perez, I. de la Calle

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report results from an intensive multiwavelength campaign on the intermediate-frequency-peaked BL Lacertae object W Com (z=0.102) during a strong outburst of very high energy gamma-ray emission in June 2008. The very high energy gamma-ray signal was detected by VERITAS on 2008 June 7-8 with a flux F(>200 GeV) = (5.7+-0.6)x10^-11 cm-2s-1, about three times brighter than during the discovery of gamma-ray emission from W Com by VERITAS in 2008 March. The initial detection of this flare by VERITAS at energies above 200 GeV was followed by observations in high energy gamma-rays (AGILE, E>100 MeV), and X-rays (Swift and XMM-Newton), and at UV, and ground-based optical and radio monitoring through the GASP-WEBT consortium and other observatories. Here we describe the multiwavelength data and derive the spectral energy distribution (SED) of the source from contemporaneous data taken throughout the flare., Comment: 26 pages, 5 figures; Accepted for publication by The Astrophysical Journal

Published
2009
Full Text
View/download PDF

18. The Fluorescence Detector of the Pierre Auger Observatory

Author

The Pierre Auger Collaboration, Abraham, J., Abreu, P., Aglietta, M., Aguirre, C., Ahn, E. J., Allard, D., Allekotte, I., Allen, J., Allison, P., Alvarez-Muñiz, J., Ambrosio, M., Anchordoqui, L., Andringa, S., Anzalone, A., Aramo, C., Arganda, E., Argirò, S., Arisaka, K., Arneodo, F., Arqueros, F., Asch, T., Asorey, H., Assis, P., Aublin, J., Ave, M., Avila, G., Bacher, A., Bäcker, T., Badagnani, D., Barber, K. B., Barbosa, A. F., Barbosa, H. J. M., Barenthien, N., Barroso, S. L. C., Baughman, B., Bauleo, P., Beatty, J. J., Beau, T., Becker, B. R., Becker, K. H., Bellétoile, A., Bellido, J. A., BenZvi, S., Berat, C., Bernardini, P., Bertou, X., Biermann, P. L., Billoir, P., Blanch-Bigas, O., Blanco, F., Bleve, C., Blümer, H., Boháčová, M., Bollmann, E., Bolz, H., Bonifazi, C., Bonino, R., Borodai, N., Bracci, F., Brack, J., Brogueira, P., Brown, W. C., Bruijn, R., Buchholz, P., Bueno, A., Burton, R. E., Busca, N. G., Caballero-Mora, K. S., Caramete, D. CaminL., Caruso, R., Carvalho, W., Castellina, A., Castro, J., Catalano, O., Cazon, L., Cester, R., Chauvin, J., Chiavassa, A., Chinellato, J. A., Chou, A., Chudoba, J., Chye, J., Clark, P. D. J., Clay, R. W., Colombo, E., Conceição, R., Connolly, B., Contreras, F., Coppens, J., Cordero, A., Cordier, A., Cotti, U., Coutu, S., Covault, C. E., Creusot, A., Criss, A., Cronin, J. W., Cuautle, J., Curutiu, A., Dagoret-Campagne, S., Dallier, R., Daudo, F., Daumiller, K., Dawson, B. R., de Almeida, R. M., De Domenico, M., De Donato, C., de Jong, S. J., De La Vega, G., Junior, W. J. M. de Mello, Neto, J. R. T. de Mello, De Mitri, I., de Souza, V., de Vries, K. D., Decerprit, G., del Peral, L., Deligny, O., Della Selva, A., Fratte, C. Delle, Dembinski, H., Di Giulio, C., Diaz, J. C., Diep, P. N., Dobrigkeit, C., D'Olivo, J. C., Dong, P. N., Dornic, D., Dorofeev, A., Anjos, J. C. dos, Dova, M. T., D'Urso, D., Dutan, I., DuVernois, M. A., Engel, R., Erdmann, M., Escobar, C. O., Etchegoyen, A., Luis, P. Facal San, Falcke, H., Farrar, G., Fauth, A. C., Fazzini, N., Ferrer, F., Ferrero, A., Fick, B., Filevich, A., Filipčič, A., Fleck, I., Fliescher, S., Fonte, R., Fracchiolla, C. E., Fraenkel, E. D., Fulgione, W., Gamarra, R. F., Gambetta, S., García, B., Gámez, D. García, Garcia-Pinto, D., Garrido, X., Geenen, H., Gelmini, G., Gemmeke, H., Ghia, P. L., Giaccari, U., Gibbs, K., Giller, M., Gitto, J., Glass, H., Goggin, L. M., Gold, M. S., Golup, G., Albarracin, F. Gomez, Berisso, M. Gómez, Vitale, P. F. Gomez, Gonçalves, P., Amaral, M. Gonçalves do, Gonzalez, D., Gonzalez, J. G., Góra, D., Gorgi, A., Gouffon, P., Grashorn, E., Grassi, V., Grebe, S., Grigat, M., Grillo, A. F., Grygar, J., Guardincerri, Y., Guardone, N., Guerard, C., Guarino, F., Gumbsheimer, R., Guedes, G. P., Gutiérrez, J., Hague, J. D., Halenka, V., Hansen, P., Harari, D., Harmsma, S., Hartmann, S., Harton, J. L., Haungs, A., Healy, M. D., Hebbeker, T., Hebrero, G., Heck, D., Hojvat, C., Holmes, V. C., Homola, P., Hofman, G., Hörandel, J. R., Horneffer, A., Horvat, M., Hrabovský, M., Hucker, H., Huege, T., Hussain, M., Iarlori, M., Insolia, A., Ionita, F., Italiano, A., Jiraskova, S., Kaducak, M., Kampert, K. H., Karova, T., Kasper, P., Kégl, B., Keilhauer, B., Kemp, E., Kern, H., Kieckhafer, R. M., Klages, H. O., Kleifges, M., Kleinfeller, J., Knapik, R., Knapp, J., Koang, D. -H., Kopmann, A., Krieger, A., Krömer, O., Kruppke-Hansen, D., Kuempel, D., Kunka, N., Kusenko, A., La Rosa, G., Lachaud, C., Lago, B. L., Lautridou, P., Leão, M. S. A. B., Lebrun, D., Lebrun, P., Lee, J., de Oliveira, M. A. Leigui, Lemiere, A., Letessier-Selvon, A., Leuthold, M., Lhenry-Yvon, I., López, R., Agüera, A. Lopez, Louedec, K., Bahilo, J. Lozano, Lucero, A., Lyberis, H., Maccarone, M. C., Macolino, C., Maldera, S., Malek, M., Mandat, D., Mantsch, P., Marchetto, F., Mariazzi, A. G., Maris, I. C., Falcon, H. R. Marquez, Martello, D., Martineau, O., Bravo, O. Martínez, Mathes, H. J., Matthews, J., Matthews, J. A. J., Matthiae, G., Maurizio, D., Mazur, P. O., McEwen, M., McNeil, R. R., Medina-Tanco, G., Melissas, M., Melo, D., Menichetti, E., Menshikov, A., Meyhandan, R., Micheletti, M. I., Miele, G., Miller, W., Miramonti, L., Mollerach, S., Monasor, M., Ragaigne, D. Monnier, Montanet, F., Morales, B., Morello, C., Moreno, J. C., Morris, C., Mostafá, M., Moura, C. A., Mucchi, M., Mueller, S., Muller, M. A., Mussa, R., Navarra, G., Navarro, J. L., Navas, S., Necesal, P., Nellen, L., Nerling, F., Newman-Holmes, C., Newton, D., Nhung, P. T., Nicotra, D., Nierstenhoefer, N., Nitz, D., Nosek, D., Nožka, L., Nyklicek, M., Oehlschläger, J., Olinto, A., Oliva, P., Olmos-Gilbaja, V. M., Ortiz, M., Ortolani, F., Oßwald, B., Pacheco, N., Selmi-Dei, D. Pakk, Palatka, M., Pallotta, J., Parente, G., Parizot, E., Parlati, S., Pastor, S., Patel, M., Paul, T., Pavlidou, V., Payet, K., Pech, M., Pȩkala, J., Pepe, I. M., Perrone, L., Pesce, R., Petermann, E., Petrera, S., Petrinca, P., Petrolini, A., Petrov, Y., Petrovic, J., Pfendner, C., Pichel, A., Piegaia, R., Pierog, T., Pimenta, M., Pinto, T., Pirronello, V., Pisanti, O., Platino, M., Pochon, J., Ponce, V. H., Pontz, M., Pouryamout, J., Prado Jr., L., Privitera, P., Prouza, M., Quel, E. J., Rautenberg, G. Raia J., Ravel, O., Ravignani, D., Redondo, A., Reis, H. C., Reucroft, S., Revenu, B., Rezende, F. A. S., Ridky, J., Riggi, S., Risse, M., Rivière, C., Rizi, V., Robledo, C., Roberts, M. D., Rodriguez, G., Martino, J. Rodriguez, Rojo, J. Rodriguez, Rodriguez-Cabo, I., Rodríguez-Frías, M. D., Ros, G., Rosado, J., Rossler, T., Roth, M., Rouillé-d'Orfeuil, B., Roulet, E., Rovero, A. C., Salamida, F., b, H. Salazar, Salina, G., Sánchez, F., Santander, M., Santo, C. E., Santos, E. M., Sarazin, F., Sarkar, S., Sato, R., Scharf, N., Scherini, V., Schieler, H., Schiffer, P., Schmidt, G. Schleif A., Schmidt, F., Schmidt, T., Scholten, O., Schoorlemmer, H., Schovancova, J., Schovánek, P., Schroeder, F., Schulte, S., Schüssler, F., Schuster, D., Sciutto, S. J., Scuderi, M., Segreto, A., Semikoz, D., Sequieros, G., Settimo, M., Shellard, R. C., Sidelnik, I., Siffert, B. B., Smiałkowski, A., Šmída, R., Smith, A. G. K., Smith, B. E., Snow, G. R., Sommers, P., Sorokin, J., Spinka, H., Squartini, R., Strazzeri, E., Stutz, A., Suarez, F., Suomijärvi, T., Supanitsky, A. D., Sutherland, M. S., Swain, J., Szadkowski, Z., Tamashiro, A., Tamburro, A., Tarutina, T., Taşcău, O., Tcaciuc, R., Tcherniakhovski, D., Thao, N. T., Thomas, D., Ticona, R., Tiffenberg, J., Timmermans, C., Tkaczyk, W., Peixoto, C. J. Todero, Tomé, B., Tonachini, A., Torres, I., Trapani, P., Travnicek, P., Tridapalli, D. B., Tristram, G., Trovato, E., Tuci, V., Tueros, M., Tusi, E., Ulrich, R., Unger, M., Urban, M., Galicia, J. F. Valdés, Valiño, I., Valore, L., Berg, A. M. van den, Vázquez, J. R., Vázquez, R. A., Veberič, D., Velarde, A., Venters, T., Verzi, V., Videla, M., Villaseñor, L., Vitali, G., Vorobiov, S., Voyvodic, L., Wahlberg, H., Wahrlich, P., Wainberg, O., Warner, D., Westerhoff, S., Whelan, B. J., Wild, N., Wiebusch, C., Wieczorek, G., Wiencke, L., Wilczyńska, B., Wilczyński, H., Wileman, C., Winnick, M. G., Wörner, G., Wu, H., Wundheiler, B., Yamamoto, T., Younk, P., Yuan, G., Yushkov, A., Zas, E., Zavrtanik, D., Zavrtanik, M., Zaw, I., b, A. Zepeda, and Ziolkowski, M.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions., Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics Research Section A

Published
2009
Full Text
View/download PDF

19. Observation of Extended VHE Emission from the Supernova Remnant IC 443 with VERITAS

Author

VERITAS Collaboration, Acciari, V. A., Aliu, E., Arlen, T., Aune, T., Bautista, M., Beilicke, M., Benbow, W., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K., Cannon, A., Celik, O., Cesarini, A., Chow, Y. C., Ciupik, L., Cogan, P., Colin, P., Cui, W., Daniel, M. K., Dickherber, R., Duke, C., Dwarkadas, V. V., Ergin, T., Fegan, S. J., Finley, J. P., Finnegan, G., Fortin, P., Fortson, L., Furniss, A., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Hays, E., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Toner, J. A., Valcarcel, L., Varlotta, A., Vassiliev, V. V., Vincent, S., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., Wood, M., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Galaxy Astrophysics
Abstract

We present evidence that the very-high-energy (VHE, E > 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 hours during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (sigma) before trials and 7.5 sigma after trials in a point-source search. The emission is centered at 06 16 51 +22 30 11 (J2000) +- 0.03_stat +- 0.08_sys degrees, with an intrinsic extension of 0.16 +- 0.03_stat +- 0.04_sys degrees. The VHE spectrum is well fit by a power law (dN/dE = N_0 * (E/TeV)^-Gamma) with a photon index of 2.99 +- 0.38_stat +- 0.3_sys and an integral flux above 300 GeV of (4.63 +- 0.90_stat +- 0.93_sys) * 10^-12 cm^-2 s^-1. These results are discussed in the context of existing models for gamma-ray production in IC 443., Comment: 7 pages, accepted by ApJL

Published
2009
Full Text
View/download PDF

20. Evidence for long-term Gamma-ray and X-ray variability from the unidentified TeV source HESS J0632+057

Author

VERITAS Collaboration, Acciari, V. A., Aliu, E., Arlen, T., Beilicke, M., Benbow, W., Boltuch, D., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Chow, Y. C., Ciupik, L., Cogan, P., Dickherber, R., Duke, C., Ergin, T., Falcone, A., Fegan, S. J., Finley, J. P., Finnegan, G., Fortin, P., Fortson, L., Furniss, A., Gibbs, K., Gillanders, G. H., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Petry, D., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Theiling, M., Toner, J. A., Varlotta, A., Vassiliev, V. V., Vincent, S., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Wissel, S., and Wood, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble known TeV binary systems like LS I +61 303 or LS 5039. HESS J0632+057 was observed by VERITAS for 31 hours in 2006, 2008 and 2009. During these observations, no significant signal in gamma rays with energies above 1 TeV was detected from the direction of HESS J0632+057. A flux upper limit corresponding to 1.1% of the flux of the Crab Nebula has been derived from the VERITAS data. The non-detection by VERITAS excludes with a probability of 99.993% that HESS J0632+057 is a steady gamma-ray emitter. Contemporaneous X-ray observations with Swift XRT reveal a factor of 1.8+-0.4 higher flux in the 1-10 keV range than earlier X-ray observations of HESS J0632+057. The variability in the gamma-ray and X-ray fluxes supports interpretation of the ob ject as a gamma-ray emitting binary., Comment: 8 pages, 3 figures, Accepted for publication in The Astrophysical Journal

Published
2009
Full Text
View/download PDF

21. VERITAS Observations of a Very High Energy Gamma-ray Flare from the Blazar 3C 66A

Author

VERITAS Collaboration, Acciari, V. A., Aliu, E., Arlen, T., Beilicke, M., Benbow, W., Bottcher, M., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K., Cannon, A., Celik, O., Cesarini, A., Chow, Y. C., Ciupik, L., Cogan, P., Cui, W., Daniel, M. K., Dickherber, R., Ergin, T., Falcone, A., Fegan, S. J., Finley, J. P., Fortin, P., Fortson, L., Furniss, A., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Hays, E., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Nagai, T., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Petry, D., Pizlo, F., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Toner, J. A., Varlotta, A., Vassiliev, V. V., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Williams, D. A., Wissel, S., Wood, M., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007 - 2008 in VHE (very high energy: E > 100 GeV) gamma-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 (sigma), in these observations (32.8 hours live time). The observed integral flux above 200 GeV is 6% of the Crab Nebula's flux and shows evidence for variability on the time-scale of days. The measured energy spectrum is characterized by a soft power law with photon index Gamma = 4.1 +- 0.4_stat +- 0.6_sys. The radio galaxy 3C 66B is excluded as a possible source of the VHE emission., Comment: 13 Pages, 4 Figures. Published in ApJL. This new version correctly calculates the intrinsic photon index (see Erratum: ApJL, 721:L203-L204)

Published
2009
Full Text
View/download PDF

23. Discovery of Very High-Energy Gamma-Ray Radiation from the BL Lac 1ES 0806+524

Author

VERITAS Collaboration, Acciari, V., Aliu, E., Arlen, T., Bautista, M., Beilicke, M., Benbow, W., Böttcher, M., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K., Cannon, A., Celik, O., Cesarini, A., Chow, Y. C., Ciupik, L., Cogan, P., Colin, P., Cui, W., Dickherber, R., Duke, C., Ergin, T., Falcone, A., Fegan, S. J., Finley, J. P., Finnegan, G., Fortin, P., Fortson, L., Furniss, A., Gall, D., Gibbs, K., Gillanders, G. H., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Hays, E., Holder, J., Horan, D., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Nagai, T., Ong, R. A., Otte, A. N., Pandel, D., Perkins, J. S., Petry, D., Pohl, M., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Theiling, M., Toner, J. A., Valcarcel, L., Varlotta, A., Vassiliev, V. V., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., White, R. J., Williams, D. A., Wissel, S., Wood, M., and Zitzer, B.

Subjects
Astrophysics
Abstract

The high-frequency-peaked BL-Lacertae object \objectname{1ES 0806+524}, at redshift z=0.138, was observed in the very-high-energy (VHE) gamma-ray regime by VERITAS between November 2006 and April 2008. These data encompass the two-, and three-telescope commissioning phases, as well as observations with the full four-telescope array. \objectname{1ES 0806+524} is detected with a statistical significance of 6.3 standard deviations from 245 excess events. Little or no measurable variability on monthly time scales is found. The photon spectrum for the period November 2007 to April 2008 can be characterized by a power law with photon index $3.6 \pm 1.0_{\mathrm{stat}} \pm 0.3_{\mathrm{sys}}$ between $\sim$300 GeV and $\sim$700 GeV. The integral flux above 300 GeV is $(2.2\pm0.5_{\mathrm{stat}}\pm0.4_{\mathrm{sys}})\times10^{-12}\:\mathrm{cm}^{2}\:\mathrm{s}^{-1}$ which corresponds to 1.8% of the Crab Nebula flux. Non contemporaneous multiwavelength observations are combined with the VHE data to produce a broadband spectral energy distribution that can be reasonably described using a synchrotron-self Compton model., Comment: 14 pages, 4 figures, accepted to APJL

Published
2008
Full Text
View/download PDF

24. VERITAS Observations of the gamma-Ray Binary LS I +61 303

Author

Acciari, V. A., Beilicke, M., Blaylock, G., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K. L., Celik, O., Cesarini, A., Ciupik, L., Chow, Y. C. K., Cogan, P., Colin, P., Cui, W., Daniel, M. K., Duke, C., Ergin, T., Falcone, A. D., Fegan, S. J., Finley, J. P., Fortin, P., Fortson, L. F., Gall, D., Gibbs, K., Gillanders, G. H., Guenette, J. Grube R., Hanna, D., Hays, E., Holder, J., Horan, D., Hughes, S. B., Hui, C. M., Humensky, T. B., Kaaret, P., Kieda, D. B., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Lee, K., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Nagai, T., Ong, R. A., Pandel, D., Perkins, J. S., Pizlo, F., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Toner, J. A., Valcarcel, L., Vassiliev, V. V., Wagner, R., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., White, R. J., Williams, D. A., Wissel, S. A., Wood, M., and Zitzer, B.

Subjects
Astrophysics
Abstract

LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy gamma-rays. The system was observed over several orbital cycles (between September 2006 and February 2007) with the VERITAS array of imaging air-Cherenkov telescopes. A signal of gamma-rays with energies above 300 GeV is found with a statistical significance of 8.4 standard deviations. The detected flux is measured to be strongly variable; the maximum flux is found during most orbital cycles at apastron. The energy spectrum for the period of maximum emission can be characterized by a power law with a photon index of Gamma=2.40+-0.16_stat+-0.2_sys and a flux above 300 GeV corresponding to 15-20% of the flux from the Crab Nebula., Comment: accepted for publication in The Astrophysical Journal

Published
2008
Full Text
View/download PDF

25. Observation of gamma-ray emission from the galaxy M87 above 250 GeV with VERITAS

Author

Acciari, V. A., Beilicke, M., Blaylock, G., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Celik, O., Cesarini, A., Ciupik, L., Cogan, P., Colin, P., Cui, W., Daniel, M. K., Duke, C., Ergin, T., Falcone, A. D., Fegan, S. J., Finley, J. P., Finnegan, G., Fortin, P., Fortson, L. F., Gibbs, K., Gillanders, G. H., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Hays, E., Holder, J., Horan, D., Hughes, S. B., Hui, M. C., Humensky, T. B., Imran, A., Kaaret, P., Kertzman, M., Kieda, D. B., Kildea, J., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Lee, K., Maier, G., McCann, A., McCutcheon, M., Millis, J., Moriarty, P., Mukherjee, R., Nagai, T., Ong, R. A., Pandel, D., Perkins, J. S., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Rose, H. J., Schroedter, M., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Toner, A. Syson J. A., Valcarcel, L., Vassiliev, V. V., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., White, R. J., Williams, D. A., Wissel, S. A., Wood, M. D., and Zitzer, B.

Subjects
Astrophysics
Abstract

The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring in Active Galactic Nuclei from radio waves to TeV gamma-rays. Here we report the detection of gamma-ray emission above 250 GeV from M87 in spring 2007 with the VERITAS atmospheric Cherenkov telescope array and discuss its correlation with the X-ray emission. The gamma-ray emission is measured to be point-like with an intrinsic source radius less than 4.5 arcmin. The differential energy spectrum is fitted well by a power-law function: dPhi/dE=(7.4+-1.3_{stat}+-1.5_{sys})(E/TeV)^{-2.31+-0.17_{stat}+-0.2_{sys}} 10^{-9}m^{-2}s^{-1}TeV^{-1}. We show strong evidence for a year-scale correlation between the gamma-ray flux reported by TeV experiments and the X-ray emission measured by the ASM/RXTE observatory, and discuss the possible short-time-scale variability. These results imply that the gamma-ray emission from M87 is more likely associated with the core of the galaxy than with other bright X-ray features in the jet., Comment: 10 pages, 7 figures, accepted for publication in The Astrophysical Journal

Published
2008
Full Text
View/download PDF

26. The First VERITAS Telescope

Author

Holder, J., Atkins, R. W., Badran, H. M., Blaylock, G., Bradbury, S. M., Buckley, J. H., Byrum, K. L., Carter-Lewis, D. A., Celik, O., Chow, Y. C. K., Cogan, P., Cui, W., Daniel, M. K., Perez, I. de la Calle, Dowdall, C., Dowkontt, P., Duke, C., Falcone, A. D., Fegan, S. J., Finley, J. P., Fortin, P., Fortson, L. F., Gibbs, K., Gillanders, G., Glidewell, O. J., Grube, J., Gutierrez, K. J., Gyuk, G., Hall, J., Hanna, D., Hays, E., Horan, D., Hughes, S. B., Humensky, T. B., Imran, A., Jung, I., Kaaret, P., Kenny, G. E., Kieda, D., Kildea, J., Knapp, J., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Linton, E., Little, E. K., Maier, G., Manseri, H., Milovanovic, A., Moriarty, P., Mukherjee, R., Ogden, P. A., Ong, R. A., Perkins, J. S., Pizlo, F., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Roache, E. T., Rose, H. J., Schroedter, M., Sembroski, G. H., Sleege, G., Steele, D., Swordy, S. P., Syson, A., Toner, J. A., Valcarcel, L., Vassiliev, V. V., Wakely, S. P., Weekes, T. C., White, R. J., Williams, D. A., and Wagner, R.

Subjects
Astrophysics
Abstract

The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV $\gamma$-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications., Comment: Accepted by Astroparticle Physics

Published
2006
Full Text
View/download PDF

27. Control Software for the VERITAS Cherenkov Telescope System

Author

Krawczynski, H., Olevitch, M., Sembroski, G., and Gibbs, K.

Subjects
Astrophysics
Abstract

The VERITAS collaboration is developing a system of initially 4 and eventually 7 Cherenkov Telescopes of the 12 m diameter class for high sensitivity gamma-ray astronomy in the >50 GeV energy range. In this contribution we describe the software that controls and monitors the various VERITAS sub-systems. The software uses an object-oriented approach to cope with the complexities that arise from using sub-groups of the 7 VERITAS telescopes to observe several sources at the same time. Inter-process communication is based on the CORBA Object Request Broker protocol and watch-dog processes monitor the sub-system performance., Comment: 4 pages to be published in the Proceedings of the 28th International Cosmic Ray Conference (Tsukuba, Japan 2003)

Published
2003

28. Recent Results from the VERITAS Collaboration

Author

Krennrich, F., Bond, I. H., Bradbury, S. M., Buckley, J. H., Carter-Lewis, D. A., Cui, W., Perez, I. de la Calle, Falcone, A., Fegan, D. J., Fegan, S. J., Finley, J. P., Gaidos, J. A., Gibbs, K., Gillanders, G. H., Hall, T. A., Hillas, A. M., Holder, J., Horan, D., Jordan, M., Kertzman, M., Kieda, D., Kildea, J., Knapp, J., Kosack, K., Lang, M. J., LeBohec, S., Moriarty, P., Muller, D., Ong, R. A., Pallassini, R., Petry, D., Quinn, J., Reynolds, P. T., Rose, H. J., Sembroski, G. H., Swordy, S. P., Vassiliev, V. V., Wakely, S. P., and Weekes, T. C.

Subjects
Astrophysics
Abstract

A decade after the discovery of TeV gamma-rays from the blazar Mrk 421 (Punch et al. 1992), the list of TeV blazars has increased to five BL Lac objects: Mrk 421 (Punch et al. 1992; Petry et al. 1996; Piron et al. 2001), Mrk 501 (Quinn et al. 1996; Aharonian et al. 1999; Djannati-Atai et al. 1999), 1ES2344+514 (Catanese et al. 1998), H1426+428 (Horan et al. 2000, 2002; Aharonian et al. 2002; Djannati-Atai et al. 2002) and 1ES1959+650 (Nishiyama et al. 1999; Konopelko et al. 2002; Holder et al. 2002). In this paper we report results from recent observations of Mrk 421, H1426+428 and 1ES1959+650 using the Whipple Observatory 10 m telescope., Comment: The Universe Viewed in Gamma-Rays proceedings

Published
2002

29. The TeV spectrum of H1426+428

Author

Petry, D., Bond, I. H., Bradbury, S. M., Buckley, J. H., Carter-Lewis, D. A., Cui, W., Duke, C., Perez, I. de la Calle, Falcone, A., Fegan, D. J., Fegan, S. J., Finley, J. P., Gaidos, J. A., Gibbs, K., Gammell, S., Hall, J., Hall, T. A., Hillas, A. M., Holder, J., Horan, D., Jordan, M., Kertzman, M., Kieda, D., Kildea, J., Knapp, J., Kosack, K., Krennrich, F., LeBohec, S., Moriarty, P., Müller, D., Nagai, T. N., Ong, R., Page, M., Pallassini, R., Power-Mooney, B., Quinn, J., Reay, N. W., Reynolds, P. T., Rose, H. J., Schroedter, M., Sembroski, G. H., Sidwell, R., Stanton, N., Swordy, S. P., Vassiliev, V. V., Wakely, S. P., Walker, G., and Weekes, T. C.

Subjects
Astrophysics
Abstract

The BL Lac object H1426+428 was recently detected as a high energy gamma-ray source by the VERITAS collaboration (Horan et al. 2002). 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 dF/dE = 10^(-7.31 +- 0.15(stat) +- 0.16(syst)) x E^(-3.50 +- 0.35(stat) +- 0.05(syst)) m^(-2)s^(-1)TeV^(-1) The statistical evidence from our data for emission above 2.5 TeV is 2.6 sigma. With 95% c.l., 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 consistent with the (non-contemporaneous) measurement by Aharonian et al. (2002) both in shape and in normalization. Below 800 GeV, the data clearly favours a spectrum steeper than that of any other TeV Blazar observed so far indicating a difference in the processes involved either at the source or in the intervening space., Comment: LaTeX, 8 pages, 4 figures, accepted for publication in ApJ

Published
2002
Full Text
View/download PDF

30. Discovery of Spectral Variability of Markarian 421 at TeV Energies

Author

Krennrich, F., Bond, I. H., Bradbury, S. M., Buckley, J. H., Carter-Lewis, D. A., Cui, W., Perez, I. de la Calle, Fegan, D. J., Fegan, S. J., Finley, J. P., Gaidos, J. A., Gibbs, K., Gillanders, G. H., Hall, T. A., Hillas, A. M., Holder, J., Horan, D., Jordan, M., Kertzman, M., Kieda, D., Kildea, J., Knapp, J., Kosack, K., Lang, M. J., LeBohec, S., Moriarty, P., Müller, D., Ong, R. A., Pallassini, R., Petry, D., Quinn, J., Reay, N. W., Reynolds, P. T., Rose, H. J., Sembroski, G. H., Sidwell, R., Stanton, N., Swordy, S. P., Vassiliev, V. V., Wakely, S. P., and Weekes, T. C.

Subjects
Astrophysics
Abstract

The detection of spectral variability of the gamma-ray blazar Mrk 421 at TeV energies is reported. Observations with the Whipple Observatory 10m gamma-ray telescope taken in 2000/2001 revealed exceptionally strong and long-lasting flaring activity. Flaring levels of 0.4 to 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 flux level. These spectra are well described by a power law with an exponential cutoff. There is no evidence for variation in the cutoff energy with flux, and all spectra are consistent with an average value for the cutoff energy of 4.3 TeV. The spectral index varies between 1.89 in a high flux state and 2.72 in a low state. The correlation between spectral index and flux is tight when averaging over the total 2000/2001 data set. Spectral measurements of Mrk~421 from previous years (1995/96 and 1999) by the Whipple collaboration are consistent with this flux-spectral index correlation, which suggest that this may be a constant or a long-term property of the source. If a similar flux-spectral index correlation were found for other gamma-ray blazars, this universal property could help disentangle the intrinsic emission mechanism from external absorption effects., Comment: 24 pages, 3 figures, submitted May 20 2002, accepted for publication in the Astrophysical Journal Letters

Published
2002
Full Text
View/download PDF

31. Cutoff in the TeV Energy Spectrum of Markarian 421 During Strong Flares in 2001

Author

Krennrich, F., Badran, H. M., Bond, I. H., Bradbury, S. M., Buckley, J. H., Carter-Lewis, D. A., Catanese, M., Cui, W., Dunlea, S., Das, D., Perez, I. de la Calle, Fegan, D. J., Fegan, S. J., Finley, J. P., Gaidos, J. A., Gibbs, K., Gillanders, G. H., Hall, T. A., Hillas, A. M., Holder, J., Horan, D., Jordan, M., Kertzman, M., Kieda, D., Kildea, J., Knapp, J., Kosack, K., Lang, M. J., LeBohec, S., McKernan, B., Moriarty, P., Müller, D., Ong, R., Pallassini, R., Petry, D., Quinn, J., Reay, N. W., Reynolds, P. T., Rose, H. J., Sembroski, G. H., Sidwell, R., Stanton, N., Swordy, S. P., Vassiliev, V. V., Wakely, S. P., and Weekes, T. C.

Subjects
Astrophysics
Abstract

Exceptionally strong and long lasting flaring activity of the blazar Markarian 421 (Mrk 421) occurred between January and March 2001. Based on the excellent signal-to-noise ratio of the data we derive the energy spectrum between 260 GeV - 17 TeV with unprecedented statistical precision. The spectrum is not well described by a simple power law even with a curvature term. Instead the data can be described by a power law with exponential cutoff: $\rm {{dN}\over{dE}} \propto \rm E^{-2.14 \pm 0.03_{stat}} \times e^{-E/E_{0}} m^{-2} s^{-1} TeV^{-1}$ with $\rm E_{0} = 4.3 \pm 0.3_{stat} TeV$. Mrk 421 is the second $\gamma$-ray blazar that unambiguously exhibits an absorption-like feature in its spectral energy distribution at 3-6 TeV suggesting that this may be a universal phenomenon, possibly due to the extragalactic infra-red background radiation., Comment: 14 pages, 3 figures, submitted to ApJL

Published
2001
Full Text
View/download PDF

32. Measurement of the Cosmic Ray Energy Spectrum and Composition from 10^{17} to 10^{18.3} eV Using a Hybrid Fluorescence Technique

Author

Abu-Zayyad, T., Belov, K., Bird, D. J., Boyer, J., Cao, Z., Catanese, M., Chen, G. F., Clay, R. W., Covault, C. E., Dai, H. Y., Dawson, B. R., Elbert, J. W., Fick, B. E., Fortson, L. F., Fowler, J. W., Gibbs, K. G., Glasmacher, M. A. K., Green, K. D., Ho, Y., Huang, A., Jui, C. C., Kidd, M. J., Kieda, D. B., Knapp, B. C., Ko, S., Larsen, C. G., Lee, W., Loh, E. C., Mannel, E. J., Matthews, J., Matthews, J. N., Newport, B. J., Nitz, D. F., Ong, R. A., Simpson, K. M., Smith, J. D., Sinclair, D., Sokolsky, P., Sommers, P., Song, C., Tang, J. K. K., Thomas, S. B., van der Velde, J., Wiencke, L. R., Wilkinson, C. R., Yoshida, S., and Zhang, X. Z.

Subjects
Astrophysics
Abstract

We study the spectrum and average mass composition of cosmic rays with primary energies between 10^{17} eV and 10^{18} eV using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing f rom a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Fly's Eye measurements and supports the previously found steepening near 4 \times 10^{17} eV ., Comment: 39 pages, 15 figures, in revtex4 epsf style, submited to APJ

Published
2000
Full Text
View/download PDF

33. A Multi-Component Measurement of the Cosmic Ray Composition Between 10^{17} eV and 10^{18} eV

Author

Abu-Zayyad, T., Belov, K., Bird, D. J., Boyer, J., Cao, Z., Catanese, M., Chen, G. F., Clay, R. W., Covault, C. E., Cronin, J. W., Dai, H. Y., Dawson, B. R., Elbert, J. W., Fick, B. E., Fortson, L. F., Fowler, J. W., Gibbs, K. G., Glasmacher, M. A. K., Green, K. D., Ho, Y., Huang, A., Jui, C. C., Kidd, M. J., Kieda, D. B., Knapp, B. C., Ko, S., Larsen, C. G., Lee, W., Loh, E. C., Mannel, E. J., Matthews, J., Matthews, J. N., Newport, B. J., Nitz, D. F., Ong, R. A., Simpson, K. M., Smith, J. D., Sinclair, D., Sokolsky, P., Sommers, P., Song, C., Tang, J. K. K., Thomas, S. B., van der Velde, J. C., Wiencke, L. R., Wilkinson, C. R., Yoshida, S., and Zhang, X. Z.

Subjects
Astrophysics
Abstract

The average mass composition of cosmic rays with primary energies between $10^{17}$eV and $10^{18}$eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum, $X_{max}$, and in the change in the muon density at a fixed core location, $\rho_\mu(600m)$, as a function of energy. The composition has also been evaluated in terms of the combination of $X_{max}$ and $\rho_\mu(600m)$. The results show that the composition is changing from a heavy to lighter mix as the energy increases., Comment: 14 pages including 3 figures in revtex epsf style, submited to PRL

Published
1999
Full Text
View/download PDF

38. Laryngoscopy and Tracheal Intubation: Does Use of a Video Laryngoscope Facilitate Both Steps of the Procedure?

Author

Lofrano, A., primary, Prekker, M.E., additional, Trent, S., additional, Russell, D.W., additional, Barnes, C., additional, Brewer, J.M., additional, Doerschug, K.C., additional, Gaillard, J., additional, Gandotra, S., additional, Ginde, A., additional, Ghamande, S., additional, Gibbs, K., additional, Hughes, C.G., additional, Janz, D.R., additional, Khan, A., additional, Mitchell, S., additional, Page, D.B., additional, Rice, T.W., additional, Self, W., additional, Smith, L.M., additional, Stempek, S., additional, Vonderhaar, D.J., additional, West, J.R., additional, Whitson, M.R., additional, Casey, J.D., additional, Semler, M.W., additional, and Driver, B., additional

Published
2023
Full Text
View/download PDF

44. Observation of Markarian 421 in TeV gamma rays over a 14-year time span

Author

Acciari, V.A., Arlen, T., Aune, T., Benbow, W., Bird, R., Bouvier, A., Bradbury, S.M., Buckley, J.H., Bugaev, V., de la Calle Perez, I., Carter-Lewis, D.A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M.P., Cui, W., Duke, C., Dumm, J., Falcone, A., Federici, S., Fegan, D.J., Fegan, S.J., Finley, J.P., Finnegan, G., Fortson, L., Gaidos, J., Galante, N., Gall, D., Gibbs, K., Gillanders, G.H., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Horan, D., Humensky, T.B., Kaaret, P., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M.J., McEnery, J.E., Madhavan, A.S., Moriarty, P., Nelson, T., O’Faoláin de Bhróithe, A., Ong, R.A., Orr, M., Otte, A.N., Perkins, J.S., Petry, D., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, T., Roache, E., Rovero, A., Schroedter, M., Sembroski, G.H., Smith, A., Telezhinsky, I., Theiling, M., Toner, J., Tyler, J., Varlotta, A., Vivier, M., Wakely, S.P., Ward, J.E., Weekes, T.C., Weinstein, A., Welsing, R., Williams, D.A., and Wissel, S.

Published
2014
Full Text
View/download PDF

47. Individualized Treatment Effects of Bougie Vs Stylet for Tracheal Intubation

Author

Spicer, A., primary, Semler, M.W., additional, Casey, J.D., additional, Driver, B., additional, Prekker, M.E., additional, Wang, L., additional, Self, W.H., additional, Ginde, A.A., additional, Trent, S.A., additional, Page, D.B., additional, Vonderhaar, D.J., additional, West, J.R., additional, Joffe, A.M., additional, Mitchell, S.H., additional, Doerschug, K.C., additional, Galliard, J.P., additional, Whitson, M.R., additional, Barnes, C.R., additional, Russell, D., additional, Gibbs, K., additional, Rice, T.W., additional, Sinha, P., additional, and Churpek, M.M., additional

Published
2022
Full Text
View/download PDF

48. NASA's Solar System Exploration Research Virtual Institute: Building Collaboration Through International Partnerships

Author

Gibbs, K. E and Schmidt, G. K

Subjects
Social And Information Sciences (General)
Abstract

The NASA Solar System Exploration Research Virtual Institute (SSERVI) is a virtual institute focused on re-search at the intersection of science and exploration, training the next generation of lunar scientists, and community development. As part of the SSERVI mission, we act as a hub for opportunities that engage the larger scientific and exploration communities in order to form new interdisciplinary, research-focused collaborations. This talk will describe the international partner re-search efforts and how we are engaging the international science and exploration communities through workshops, conferences, online seminars and classes, student exchange programs and internships.

Published
2017

49. Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar

Author

Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nuñez, P., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Published
2011
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results