@article{Abel2004, author = {Abel, Markus}, title = {Nonparametric modeling and spatiotemporal dynamical systems}, issn = {0218-1274}, year = {2004}, abstract = {This article describes how to use statistical data analysis to obtain models directly from data. The focus is put on finding nonlinearities within a generalized additive model. These models are found by means of backfitting or more general algorithms, like the alternating conditional expectation value one. The method is illustrated by numerically generated data. As an application, the example of vortex ripple dynamics, a highly complex fluid-granular system, is treated}, language = {en} } @article{AbelAhnertKurthsetal.2005, author = {Abel, Markus and Ahnert, Karsten and Kurths, R. and Mandelj, S.}, title = {Additive nonparametric reconstruction of dynamical systems from time series}, issn = {1063-651X}, year = {2005}, abstract = {We present a nonparametric way to retrieve an additive system of differential equations in embedding space from a single time series. These equations can be treated with dynamical systems theory and allow for long-term predictions. We apply our method to a modified chaotic Chua oscillator in order to demonstrate its potential}, language = {en} } @article{AbelBergweilerGerhard2006, author = {Abel, Markus and Bergweiler, Steffen and Gerhard, Reimund}, title = {Synchronization of organ pipes : experimental observations and modeling}, issn = {0001-4966}, doi = {10.1121/1.217044}, year = {2006}, abstract = {We report measurements on the synchronization properties of organ pipes. First, we investigate influence of an external acoustical signal from a loudspeaker on the sound of an organ pipe. Second, the mutual influence of two pipes with different pitch is analyzed. In analogy to the externally driven, or mutually coupled self-sustained oscillators, one observes a frequency locking, which can be explained by synchronization theory. Further, we measure the dependence of the frequency of the signals emitted by two mutually detuned pipes with varying distance between the pipes. The spectrum shows a broad '' hump '' structure, not found for coupled oscillators. This indicates a complex coupling of the two organ pipes leading to nonlinear beat phenomena.}, language = {en} } @article{AbelCelaniErgnietal.2002, author = {Abel, Markus and Celani, A. and Ergni, V. and Vulpiani, A.}, title = {Front speed enhancement in cellular flows}, issn = {1054-1500}, year = {2002}, language = {en} } @article{AbelCelaniVergenietal.2001, author = {Abel, Markus and Celani, A. and Vergeni, D. and Vulpiani, A.}, title = {Front propagation in laminar flows}, year = {2001}, abstract = {The Problem of front propagation in flowing media is addressed for laminar velocity fields in two dimensions. Three representative cases are discussed: stationary cellular flow, stationary shear flow, and percolating flow. Production terms of Fisher-Kolmogorov-Petrovskii-Piskunov type and of Arrhenius type are considered under the assumption of no feedback of the concentration on the velocity. Numerical simulations of advection-reaction-diffusion equations have been performed by an algorithm based on discrete-time maps. The results show a generic enhancement of the speed of front propagation by the underlying flow. For small molecular diffusivity, the front speed Vf depends on the typical flow velocity U as a power law with an exponent depending on the topological properties of the flow, and on the ratio of reactive and advective time scales. For open-streamline flows we find always Vf~U, whereas for cellular flows we observe Vf~U1/4 for fast advection and Vf~U3/4 for slow advection.}, language = {en} } @article{AbelFlachPikovskij1998, author = {Abel, Markus and Flach, S. and Pikovskij, Arkadij}, title = {Localisation in a coupled standard map lattice}, year = {1998}, abstract = {We study spatially localized excitations in a lattice of coupled standard maps. Time-periodic solutions (breathers) exist in a range of coupling that is shown to shrink as the period grows to infinity, thus excluding the possibility of time-quasiperiodic breathers. The evolution of initially localized chaotic and quasiperiodic states in a lattice is studied numerically. Chaos is demonstrated to spread}, language = {en} } @article{AbelFlachPikovskij1998, author = {Abel, Markus and Flach, S. and Pikovskij, Arkadij}, title = {Localization in a coupled standard map lattice}, year = {1998}, language = {en} } @article{AbelPikovskij1997, author = {Abel, Markus and Pikovskij, Arkadij}, title = {Parametric excitation of breathers in a nonlinear lattice}, year = {1997}, abstract = {We investigate localized periodic solutions (breathers) in a lattice of parametrically driven, nonlinear dissipative oscillators. These breathers are demonstrated to be exponentially localized, with two characteristic localization lengths. The crossover between the two lengths is shown to be related to the transition in the phase of the lattice oscillations.}, language = {en} } @article{AbelSpicci1998, author = {Abel, Markus and Spicci, M.}, title = {Nonlinear localization periodic solutions in a coupled map lattice}, year = {1998}, abstract = {We prove the existence of nonlinear localized time-periodic solutions in a chain of symplectic mappings with nearest neighbour coupling. This is a class of systems whose behaviour can be seen as representation of a lattice of pendula. The effect of discrete time changes the mathematical as well as the numerical procedures. Applying the discrete version of Floquet theory eases and clarifies the procedure of proving the existence of the localized time-periodic solutions. As an extension of the concept of rotobreathers one can produce solutions which rotate at every site of the lattice. To consider these we use a general definition of localization.}, language = {en} } @article{AbelStojkovicBreuer2006, author = {Abel, Markus and Stojkovic, Dragan and Breuer, Michael}, title = {Nonlinear stochastic estimation of wall models for LES}, issn = {0142-727X}, doi = {10.1016/j.heatfluidflow.2005.10.011}, year = {2006}, abstract = {A key technology for large eddy simulation (LES) of complex flows is an appropriate wall modeling strategy. In this paper we apply for the first time a fully nonparametric procedure for the estimation of generalized additive models (GAM) by conditional statistics. As a database, we use DNS and wall-resolved LES data of plane channel flow for Reynolds numbers, Re = 2800, 4000 (DNS) and 10,935, 22,776 (LES). The statistical method applied is a quantitative tool for the identification of important model terms, allowing for an identification of some of the near-wall physics. The results are given as nonparametric functions which cannot be attained by other methods. We investigated a generalized model which includes Schumann's and Piomelli et al.'s model. A strong influence of the pressure gradient in the viscous sublayer is found; for larger wall distances the spanwise pressure gradient even dominates the tau(w,zy). component. The first a posteriori LES results are given.}, language = {en} } @article{AbelerCalakiAndreeetal.2010, author = {Abeler, Johannes and Calaki, Juljana and Andree, Kai and Basek, Christoph}, title = {The power of apology}, issn = {0165-1765}, doi = {10.1016/j.econlet.2010.01.033}, year = {2010}, abstract = {How should firms react to customer complaints after an unsatisfactory purchase? In a field experiment, we test the effect of different reactions and find that a cheap-talk apology yields significantly better outcomes for the firm than offering a monetary compensation.}, language = {en} } @article{AbercrombieAndersonBaldwinetal.2009, author = {Abercrombie, Laura Good and Anderson, Cynthia M. and Baldwin, Bruce G. and Bang, In-Chul and Beldade, Ricardo and Bernardi, Giacomo and Boubou, Angham and Branca, Antoine and Bretagnolle, Francois and Bruford, Michael W. and Buonamici, Anna and Burnett, Robert K. and Canal, D. and Cardenas, H. and Caullet, Coraline and Chen, S. Y. and Chun, Y. J. and Cossu, C. and Crane, Charles F. and Cros-Arteil, Sandrine and Cudney-Bueno, Richard and Danti, Roberto and Davila, Jos{\´e} Antonio and Della Rocca, Gianni and Dobata, Shigeto and Dunkle, Larry D. and Dupas, Stephane and others}, title = {Permanent genetic resources added to molecular ecology resources database 1 January 2009-30 April 2009}, issn = {1755-098X}, doi = {10.1111/j.1755-0998.2009.02746.x}, year = {2009}, abstract = {This article documents the addition of 283 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Agalinis acuta; Ambrosia artemisiifolia; Berula erecta; Casuarius casuarius; Cercospora zeae-maydis; Chorthippus parallelus; Conyza canadensis; Cotesia sesamiae; Epinephelus acanthistius; Ficedula hypoleuca; Grindelia hirsutula; Guadua angustifolia; Leucadendron rubrum; Maritrema novaezealandensis; Meretrix meretrix; Nilaparvata lugens; Oxyeleotris marmoratus; Phoxinus neogaeus; Pristomyrmex punctatus; Pseudobagrus brevicorpus; Seiridium cardinale; Stenopsyche marmorata; Tetranychus evansi and Xerus inauris. These loci were cross-tested on the following species: Agalinis decemloba; Agalinis tenella; Agalinis obtusifolia; Agalinis setacea; Agalinis skinneriana; Cercospora zeina; Cercospora kikuchii; Cercospora sorghi; Mycosphaerella graminicola; Setosphaeria turcica; Magnaporthe oryzae; Cotesia flavipes; Cotesia marginiventris; Grindelia Xpaludosa; Grindelia chiloensis; Grindelia fastigiata; Grindelia lanceolata; Grindelia squarrosa; Leucadendron coniferum; Leucadendron salicifolium; Leucadendron tinctum; Leucadendron meridianum; Laodelphax striatellus; Sogatella furcifera; Phoxinus eos; Phoxinus rigidus; Phoxinus brevispinosus; Phoxinus bicolor; Tetranychus urticae; Tetranychus turkestani; Tetranychus ludeni; Tetranychus neocaledonicus; Tetranychus amicus; Amphitetranychus viennensis; Eotetranychus rubiphilus; Eotetranychus tiliarium; Oligonychus perseae; Panonychus citri; Bryobia rubrioculus; Schizonobia bundi; Petrobia harti; Xerus princeps; Spermophilus tridecemlineatus and Sciurus carolinensis.}, language = {en} } @article{AberleMalzahnBauerLewandowskaetal.2012, author = {Aberle-Malzahn, Nicole and Bauer, Barbara and Lewandowska, A. and Gaedke, Ursula and Sommer, U.}, title = {Warming induces shifts in microzooplankton phenology and reduces time-lags between phytoplankton and protozoan production}, series = {Marine biology : international journal on life in oceans and coastal waters}, volume = {159}, journal = {Marine biology : international journal on life in oceans and coastal waters}, number = {11}, publisher = {Springer}, address = {New York}, issn = {0025-3162}, doi = {10.1007/s00227-012-1947-0}, pages = {2441 -- 2453}, year = {2012}, abstract = {Indoor mesocosm experiments were conducted to test for potential climate change effects on the spring succession of Baltic Sea plankton. Two different temperature (Delta 0 A degrees C and Delta 6 A degrees C) and three light scenarios (62, 57 and 49 \% of the natural surface light intensity on sunny days), mimicking increasing cloudiness as predicted for warmer winters in the Baltic Sea region, were simulated. By combining experimental and modeling approaches, we were able to test for a potential dietary mismatch between phytoplankton and zooplankton. Two general predator-prey models, one representing the community as a tri-trophic food chain and one as a 5-guild food web were applied to test for the consequences of different temperature sensitivities of heterotrophic components of the plankton. During the experiments, we observed reduced time-lags between the peaks of phytoplankton and protozoan biomass in response to warming. Microzooplankton peak biomass was reached by 2.5 day A degrees C-1 earlier and occurred almost synchronously with biomass peaks of phytoplankton in the warm mesocosms (Delta 6 A degrees C). The peak magnitudes of microzooplankton biomass remained unaffected by temperature, and growth rates of microzooplankton were higher at Delta 6 A degrees C (mu(a dagger 0 A degrees C) = 0.12 day(-1) and mu(a dagger 6 A degrees C) = 0.25 day(-1)). Furthermore, warming induced a shift in microzooplankton phenology leading to a faster species turnover and a shorter window of microzooplankton occurrence. Moderate differences in the light levels had no significant effect on the time-lags between autotrophic and heterotrophic biomass and on the timing, biomass maxima and growth rate of microzooplankton biomass. Both models predicted reduced time-lags between the biomass peaks of phytoplankton and its predators (both microzooplankton and copepods) with warming. The reduction of time-lags increased with increasing Q(10) values of copepods and protozoans in the tritrophic food chain. Indirect trophic effects modified this pattern in the 5-guild food web. Our study shows that instead of a mismatch, warming might lead to a stronger match between protist grazers and their prey altering in turn the transfer of matter and energy toward higher trophic levels.}, language = {en} } @article{AbetzJiangGopfert2004, author = {Abetz, Volker and Jiang, S. M. and Gopfert, A.}, title = {Novel pattern formation in blends of asymmetric ABC triblock terpolymers}, issn = {1618-7229}, year = {2004}, abstract = {A series of polystyrene-block-poly(1,2-butadiene)-block-poly(2-vinyl-pyridine) (SBV) triblock terpolymers were used to prepare blends with symmetric polystyrene-block-poly(2-vinylpyridine) (SV) and poly(2-vinylpyridine)-block-poly- (cyclohexyl methacrylate) (VC) diblock copolymers. Morphological characterization was carried out by transmission electron microscopy. These triblock terpolymers self-assemble into various core-shell type or lamellar morphologies. In the SBV/SV blends, macrophase separation between the two block copolymers, continuous centrosymmetric lamellae and stacks of non-centrosymmetric lamellae with anti-parallel orientation were found. In the blends of SBV/VC, macrophase separation was never observed, what is due to the specific interactions between S and C domains. These systems showed among other morphologies also a cylindrical morphology in which rings surround the cylinders}, language = {en} } @article{AbeysekaraArchambaultArcheretal.2016, author = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Biteau, Jonathan and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cardenzana, J. V. and Cerruti, M. and Chen, Xuhui and Christiansen, J. L. and Ciupik, L. and Connolly, M. P. and Cui, W. and Dickinson, H. J. and Dumm, J. and Eisch, J. D. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Flinders, A. and Fortin, P. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Gyuk, G. and Huetten, M. and Hanna, D. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Pelassa, V. and Petrashyk, A. and Petry, D. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Ratliff, G. and Reyes, L. C. and Reynolds, P. T. and Reynolds, K. and Richards, G. T. and Roache, E. and Rulten, C. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Smith, A. W. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Vincent, S. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Wilhelm, Alina and Williams, D. A. and Zitzer, B.}, title = {VERITAS and multiwavelength observations of the BL Lacertae object 1ES 1741+196}, series = {Monthly notices of the Royal Astronomical Society}, volume = {459}, journal = {Monthly notices of the Royal Astronomical Society}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stw664}, pages = {2550 -- 2557}, year = {2016}, abstract = {We present results from multiwavelength observations of the BL Lacertae object 1ES 1741 + 196, including results in the very high energy gamma-ray regime using the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The VERITAS time-averaged spectrum, measured above 180 GeV, is well modelled by a power law with a spectral index of 2.7 +/- 0.7(stat) +/- 0.2(syst). The integral flux above 180 GeV is (3.9 +/- 0.8(stat) +/- 1.0(syst)) x 10(-8) m(-2) s(-1), corresponding to 1.6 per cent of the Crab nebula flux on average. The multiwavelength spectral energy distribution of the source suggests that 1ES 1741+196 is an extreme-high-frequency-peaked BL Lacertae object. The observations analysed in this paper extend over a period of six years, during which time no strong flares were observed in any band. This analysis is therefore one of the few characterizations of a blazar in a non-flaring state.}, language = {en} } @article{AbeysekaraArchambaultArcheretal.2017, author = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Brose, Robert and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Cerruti, M. and Connolly, M. P. and Cui, W. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Huetten, M. and Hanna, D. and Hervet, O. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Petrashyk, A. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tyler, J. and Vassiliev, V. V. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Wilcox, P. and Wilhelm, Alina and Williams, D. A. and Zitzer, B.}, title = {Discovery of Very-high-energy Emission from RGB J2243+203 and Derivation of Its Redshift Upper Limit}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, volume = {233}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0067-0049}, doi = {10.3847/1538-4365/aa8d76}, pages = {1188 -- 1204}, year = {2017}, abstract = {Very-high-energy (VHE; > 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 2014 December 21 and 24. The VERITAS energy spectrum from this source can be fitted by a power law with a photon index of 4.6 +/- 0.5, and a flux normalization at 0.15 TeV of (6.3 +/- 1.1) x 10(-10) cm(-2) s(-1) TeV-1. The integrated Fermi-LAT flux from 1 to 100 GeV during the VERITAS detection is (4.1 +/- 0.8) x 10(-8) cm(-2) s(-1), which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, (4.0 +/- 0.1 x 10(-9) cm(-2) s(-1)). The detection with VERITAS triggered observations in the X-ray band with the Swift-XRT. However, due to scheduling constraints Swift-XRT observations were performed 67 hr after the VERITAS detection, rather than simultaneously with the VERITAS observations. The observed X-ray energy spectrum between 2 and 10 keV can be fitted with a power law with a spectral index of 2.7 +/- 0.2, and the integrated photon flux in the same energy band is (3.6 +/- 0.6) x 10(-13) cm(-2) s(-1). EBL-model-dependent upper limits of the blazar redshift have been derived. Depending on the EBL model used, the upper limit varies in the range from z < 0.9 to z < 1.1.}, language = {en} } @article{AbeysekaraArchambaultArcheretal.2016, author = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, W. and Bird, R. and Buchovecky, M. and Buckley, J. H. and Byrum, K. and Cardenzana, J. V. and Cerruti, M. and Chen, Xuhui and Christiansen, J. L. and Ciupik, L. and Cui, W. and Dickinson, H. J. and Eisch, J. D. and Errando, M. and Falcone, A. and Fegan, D. J. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortin, P. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Gyuk, G. and Huetten, M. and Hakansson, Nils and Hanna, D. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Lin, T. T. Y. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Perkins, J. S. and Petrashyk, A. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Ratliff, G. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Vincent, S. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Williams, D. A. and Zitzer, B.}, title = {A SEARCH FOR BRIEF OPTICAL FLASHES ASSOCIATED WITH THE SETI TARGET KIC 8462852}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, volume = {818}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {2041-8205}, doi = {10.3847/2041-8205/818/2/L33}, pages = {6}, year = {2016}, abstract = {The F-type star KIC. 8462852 has recently been identified as an exceptional target for search for extraterrestrial intelligence (SETI) observations. We describe an analysis methodology for optical SETI, which we have used to analyze nine hours of serendipitous archival observations of KIC. 8462852 made with the VERITAS gamma-ray observatory between 2009 and 2015. No evidence of pulsed optical beacons, above a pulse intensity at the Earth of approximately 1 photon m(-2), is found. We also discuss the potential use of imaging atmospheric Cherenkov telescope arrays in searching for extremely short duration optical transients in general.}, language = {en} } @article{AbeysekaraArchambaultArcheretal.2017, author = {Abeysekara, A. U. and Archambault, S. and Archer, A. and Benbow, Wystan and Bird, Ralph and Buchovecky, M. and Buckley, J. H. and Bugaev, V. and Byrum, K. and Cerruti, M. and Chen, X. and Ciupik, L. and Cui, W. and Dickinson, H. J. and Eisch, J. D. and Errando, M. and Falcone, A. and Feng, Q. and Finley, J. P. and Fleischhack, H. and Fortson, L. and Furniss, A. and Gillanders, G. H. and Griffin, S. and Grube, J. and Hutten, M. and Hakansson, N. and Hanna, D. and Holder, J. and Humensky, T. B. and Johnson, C. A. and Kaaret, P. and Kar, P. and Kertzman, M. and Kieda, D. and Krause, M. and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, G. and McArthur, S. and McCann, A. and Meagher, K. and Moriarty, P. and Mukherjee, R. and Nguyen, T. and Nieto, D. and Ong, R. A. and Otte, A. N. and Park, N. and Pelassa, V. and Pohl, Martin and Popkow, A. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, G. T. and Roache, E. and Rulten, C. and Santander, M. and Sembroski, G. H. and Shahinyan, K. and Staszak, D. and Telezhinsky, Igor O. and Tucci, J. V. and Tyler, J. and Wakely, S. P. and Weiner, O. M. and Weinstein, A. and Wilhelm, Alina and Williams, D. A. and Fegan, S. and Giebels, B. and Horan, D. and Berdyugin, A. and Kuan, J. and Lindfors, E. and Nilsson, K. and Oksanen, A. and Prokoph, H. and Reinthal, R. and Takalo, L. and Zefi, F.}, title = {A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {836}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, organization = {VERITAS Collaboration;Fermi-LAT Collaboration}, issn = {0004-637X}, doi = {10.3847/1538-4357/836/2/205}, pages = {6}, year = {2017}, abstract = {B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2. 1215+30 during routine monitoring observations of the blazar 1ES. 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of <3.6 hr. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a onezone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor delta > 10, and an electron population with spectral index p < 2.3.}, language = {en} } @article{AbeysekaraArcherAuneetal.2018, author = {Abeysekara, A. U. and Archer, A. and Aune, Taylor and Benbow, Wystan and Bird, Ralph and Brose, Robert and Buchovecky, M. and Bugaev, V. and Cui, Wei and Daniel, M. K. and Falcone, A. and Feng, Qi and Finley, John P. and Fleischhack, H. and Flinders, A. and Fortson, L. and Furniss, Amy and Gotthelf, Eric V. and Grube, J. and Hanna, David and Hervet, O. and Holder, J. and Huang, K. and Hughes, G. and Humensky, T. B. and Huetten, M. and Johnson, Caitlin A. and Kaaret, Philip and Kar, P. and Kelley-Hoskins, N. and Kertzman, M. and Kieda, David and Krause, Maria and Kumar, S. and Lang, M. J. and Lin, T. T. Y. and Maier, Gernot and McArthur, S. and Moriarty, P. and Mukherjee, Reshmi and Ong, R. A. and Otte, Adam Nepomuk and Pandel, Dirk and Park, Nahee and Petrashyk, A. and Pohl, Martin and Popkow, Alexis and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Richards, Gregory T. and Roache, E. and Rousselle, J. and Rulten, C. and Sadeh, I. and Santander, M. and Sembroski, G. H. and Shahinyan, Karlen and Tyler, J. and Vassiliev, V. V. and Wakely, S. P. and Ward, J. E. and Weinstein, A. and Wells, R. M. and Wilcox, P. and Wilhelm, Alina and Williams, David A. and Zitzer, B.}, title = {A Very High Energy gamma-Ray Survey toward the Cygnus Region of the Galaxy}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {861}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/aac4a2}, pages = {33}, year = {2018}, abstract = {We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE)gamma-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy.-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse gamma-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE gamma-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3\% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed gamma-ray view of the region to date.}, language = {en} } @article{AbeysekaraArcherBenbowetal.2019, author = {Abeysekara, A. U. and Archer, A. and Benbow, Wystan and Bird, Ralph and Brill, A. and Brose, Robert and Buchovecky, M. and Calderon-Madera, D. and Christiansen, J. L. and Cui, W. and Daniel, M. K. and Falcone, A. and Feng, Q. and Fernandez-Alonso, M. and Finley, J. P. and Fortson, Lucy and Furniss, Amy and Gent, A. and Giuri, C. and Gueta, O. and Hanna, David and Hassan, T. and Hervet, Oliver and Holder, J. and Hughes, G. and Humensky, T. B. and Johnson, Caitlin A. and Kaaret, P. and Kertzman, M. and Kieda, David and Krause, Maria and Krennrich, F. and Kumar, S. and Lang, M. J. and Maier, Gernot and Moriarty, P. and Mukherjee, Reshmi and Nievas-Rosillo, M. and Ong, R. A. and Pfrang, Konstantin Johannes and Pohl, Martin and Prado, R. R. and Pueschel, Elisa and Quinn, J. and Ragan, K. and Reynolds, P. T. and Ribeiro, D. and Richards, G. T. and Roache, E. and Rovero, A. C. and Sadeh, Iftach and Santander, M. and Sembroski, G. H. and Shahinyan, Karlen and Sushch, Iurii and Svraka, T. and Weinstein, A. and Wells, R. M. and Wilcox, Patrick and Wilhelm, Alina and Williams, David Arnold and Williamson, T. J. and Zitzer, B.}, title = {Measurement of the Extragalactic Background Light Spectral Energy Distribution with VERITAS}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {885}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.3847/1538-4357/ab4817}, pages = {8}, year = {2019}, abstract = {The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is a record of radiative processes over the universe?s history. Spectral measurements of blazars at very high energies (>100 GeV) enable the reconstruction of the spectral energy distribution (SED) of the EBL, as the blazar spectra are modified by redshift- and energy-dependent interactions of the gamma-ray photons with the EBL. The spectra of 14 VERITAS-detected blazars are included in a new measurement of the EBL SED that is independent of EBL SED models. The resulting SED covers an EBL wavelength range of 0.56?56 ?m, and is in good agreement with lower limits obtained by assuming that the EBL is entirely due to radiation from cataloged galaxies.}, language = {en} }