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2. D‐dimer testing for early detection of venom‐induced consumption coagulopathy after snakebite in Australia (ASP‐29).

Author

Isbister, Geoffrey K, Noutsos, Tina, Jenkins, Shane, Isoardi, Katherine Z, Soderstrom, Jessamine, and Buckley, Nicholas A

Abstract

Objective: To assess the accuracy and marginal value of quantitative D‐dimer testing for diagnosing venom‐induced consumption coagulopathy (VICC) in people bitten by Australian snakes. Design, setting: Analysis of data for suspected and confirmed cases of snakebite collected prospectively by the Australian Snakebite Project, 2005–2019, from 200 hospitals across Australia. Participants: 1363 patients for whom D‐dimer was quantitatively assessed within 24 hours of suspected or confirmed snakebite. Main outcome measures: Diagnostic performance of quantitative D‐dimer testing for detecting systemic envenoming with VICC (area under the receiver operating characteristic curve, AUC); optimal D‐dimer cut‐off value (maximum sum of sensitivity and specificity). Results: D‐dimer values exceeded 2.5 mg/L within three hours of the bite for 95% of patients who developed VICC, and were lower than 2.5 mg/L for 95% of non‐envenomed patients up to six hours after snakebite. The AUC for diagnosing envenoming with VICC on the basis of quantitative D‐dimer testing within six hours of snakebite was 0.97 (95% CI, 0.96–0.98; 944 patients). Diagnostic performance increased during the first three hours after snakebite; for quantitative D‐dimer testing at 2–6 hours, the AUC was 0.99 (95% CI, 0.99–1.0); with a cut‐off of 2.5 mg/L, sensitivity was 97.1% (95% CI, 95.0–98.3%) and specificity 99.0% (95% CI, 97.6–99.6%) for VICC. For 36 patients with normal international normalised ratio (INR) and activated partial thromboplastin time (aPTT) values 2–6 hours after snakebite, the AUC was 0.97 (95% CI, 0.93–1.0); with a cut‐off of 1.4 mg/L, sensitivity was 94% (95% CI, 82–99%) and specificity 96% (95% CI, 94–97%). In all but one of 84 patients who developed VICC‐related acute kidney injury, D‐dimer values exceeded 4 mg/L within 24 hours of the bite. Conclusion: D‐dimer concentrations assessed 2–6 hours after snakebite, with a cut‐off value of 2.5 mg/L, could be useful for diagnosing envenoming with VICC. [ABSTRACT FROM AUTHOR]

Published
2022
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3. Spatiotemporal analysis of setting per game complex and origin of the ball in junior female volleyball players.

Author

OIKONOMOPOULOU, AIKATERINI, BARZOUKA, KAROLINA, SOTIROPOULOS, KONSTANTINOS, DRIKOS, SOTIRIOS, and NOUTSOS, KONSTANTINOS

Abstract

In volleyball, the performance in the passing affects the setter's strategy and the effectiveness of the attack after the reception or defense. This study aims to assess the spatial and temporal characteristics of the setting choices made by junior female volleyball setters and their performance concerning the origin of the ball and the game complex. The sample for this analysis consists of 3728 setting actions (Complex I = 1.616, Complex II = 1.212). A three-member group of experienced coaches assessed the setting zones' choices as well as the setting tempo and the performance of junior female setters from 20 volleyball games of teams competing in the final phase of the Greek Junior Championship. The variables under consideration were complex of the game (C1 & CII), origin of the ball (left/middle/right lane for the vertical and front/centre/back lane for the horizontal axis of the court), setting zone (six zones of the court), setting tempo (1st, 2nd & 3rd tempo) and setting performance in a five-level ordinal scale. Inter-rater and intra-rater reliability coefficients were estimated using Cohen's kappa coefficient with acceptable values. The test of independence for the categorical variables was carried out using the chi-square test. Following the overall independence test, the difference in proportions among all levels of variables was tested. Results showed that junior female setters regardless of the complex and the origin of the ball choose zone 4 in a 3rd tempo, performed in a moderate and good setting. However, the origin of the ball was an important variable for the subsequent setting. The most preferable route of the ball was from a pass in the left lane of the court to an attack in zone 4 regardless of the game complex. Additionally, setters when receiving the ball from the left and middle lane of the court prefer more often zone 3 in 1st tempo, during CI than CII. The results of the study will give useful directions to the coaches of the specific age category regarding the creation of appropriate training programs for the individual improvement of the setters and teams. [ABSTRACT FROM AUTHOR]

Published
2022
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4. D‐dimer testing for early detection of venom‐induced consumption coagulopathy after snakebite in Australia (ASP‐29)

Author

Isbister, Geoffrey K, Noutsos, Tina, Jenkins, Shane, Isoardi, Katherine Z, Soderstrom, Jessamine, and Buckley, Nicholas A

Abstract

To assess the accuracy and marginal value of quantitative D‐dimer testing for diagnosing venom‐induced consumption coagulopathy (VICC) in people bitten by Australian snakes. Analysis of data for suspected and confirmed cases of snakebite collected prospectively by the Australian Snakebite Project, 2005–2019, from 200 hospitals across Australia. 1363 patients for whom D‐dimer was quantitatively assessed within 24 hours of suspected or confirmed snakebite. Diagnostic performance of quantitative D‐dimer testing for detecting systemic envenoming with VICC (area under the receiver operating characteristic curve, AUC); optimal D‐dimer cut‐off value (maximum sum of sensitivity and specificity). D‐dimer values exceeded 2.5 mg/L within three hours of the bite for 95% of patients who developed VICC, and were lower than 2.5 mg/L for 95% of non‐envenomed patients up to six hours after snakebite. The AUC for diagnosing envenoming with VICC on the basis of quantitative D‐dimer testing within six hours of snakebite was 0.97 (95% CI, 0.96–0.98; 944 patients). Diagnostic performance increased during the first three hours after snakebite; for quantitative D‐dimer testing at 2–6 hours, the AUC was 0.99 (95% CI, 0.99–1.0); with a cut‐off of 2.5 mg/L, sensitivity was 97.1% (95% CI, 95.0–98.3%) and specificity 99.0% (95% CI, 97.6–99.6%) for VICC. For 36 patients with normal international normalised ratio (INR) and activated partial thromboplastin time (aPTT) values 2–6 hours after snakebite, the AUC was 0.97 (95% CI, 0.93–1.0); with a cut‐off of 1.4 mg/L, sensitivity was 94% (95% CI, 82–99%) and specificity 96% (95% CI, 94–97%). In all but one of 84 patients who developed VICC‐related acute kidney injury, D‐dimer values exceeded 4 mg/L within 24 hours of the bite. D‐dimer concentrations assessed 2–6 hours after snakebite, with a cut‐off value of 2.5 mg/L, could be useful for diagnosing envenoming with VICC.

Published
2022
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5. Band-times-circulant preconditioners for non-symmetric Toeplitz systems

Author

Noutsos, Dimitrios and Tachyridis, Grigorios

Abstract

In this paper we study n×nnon-symmetric, real Toeplitz systems of the form Tn(f)x=b, where the generating function of the Toeplitz matrix fis known a priori. We study the behavior of a specific circulant preconditioner and we also propose a preconditioner arising from the combination of a band Toeplitz matrix and circulant matrices, for ill-conditioned Toeplitz systems. For the solution of the system we use Krylov subspace methods and more specifically the Conjugate Gradient method for the corresponding preconditioned system of the normal equations and the Preconditioned Generalized Minimal Residual method. We prove theoretical results, which guarantee the efficiency of the proposed preconditioner either when fis continuous or it is piecewise continuous. We emphasize that fmay have zeros in (-π,π]. Finally, we present various numerical experiments, where the efficiency of the proposed preconditioning technique is shown, since we get the solution of the preconditioned system in a small number of iterations.

Published
2022
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6. Relationship between throwing accuracy and performance indices in female and male adolescent handball players.

Author

FRAGOULA, PAPANIKOLAOY, ELISSAVET, ROUSANOGLOU N., MARIA, PSYCHOUNTAKI, and KONSTANTINOS, NOUTSOS S.

Abstract

The purposes of this study were to (i) investigate the relationship between overhead throwing accuracy and anthropometric and maturity characteristics, kinesthesis, self-efficacy, and the angular kinematics of the hand and (ii) examine the differences in all variables in the study between female and male adolescent handball players. Methods: The participants of this study were 30 handball players aged 14-16 years (n = 15 females, n = 15 males). Anthropometric and maturity characteristics were recorded for each player; psychomotor indices and overhead throwing accuracy were then tested. Results: Several correlations were revealed between overhead throwing accuracy and the subject parameters this study. Specifically, for the adolescent females, chronological age (r= 0.586; p= 0.022) and the age of peak high velocity (APHV) (r= 0.645; p= 0.009) had a positive effect on the throwing accuracy, while ectomorphy (r= -0.520; p= 0.047) and kinesthesis (r= -0.603; p= 0.017) had a negative effect. For the adolescent males, the APHV (r= 0.659; p= 0.008), the standing height (r= 0.714; p=0.003), and the sitting height (r= 0.554; p= 0.032) positively affected the throwing accuracy, while mesomorphy (r= -0.526; p= 0.044) affected it negatively. Between the two genders, significant differences were detected for the parameters of chronological age (F=6.63; p= 0.016), APHV (F=14.56; p=0.001), standing height (F=7.28; p=0.01), mesomorphy (F=10.71; p=0.003), biacromial breadth (F=22.34; p=0.000), forearm length (F=4.82; p=0.03), and hand width (F=8.37; p=0.007), as well as the level (F=13.54; p=0.001) and strength of self-efficacy (F=12.38; p=0.001). Conclusion: These findings may provide important information to formulate coaching interventions with the choice of suitable exercises with a view to improving the throwing efficacy of handball players. [ABSTRACT FROM AUTHOR]

Published
2021
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7. An evaluation of existing manual blood film schistocyte quantitation guidelines and a new proposed method

Author

Noutsos, Tina, Laidman, Alexandra Y., Survela, Lesley, Arvanitis, Dorra, Segalla, Renee, Brown, Simon G., and Isbister, Geoffrey K.

Abstract

Schistocytosis is the morphological hallmark of the microangiopathic haemolytic anaemia of thrombotic microangiopathy (TMA). Consensus guidelines for manual schistocyte quantitation are available, but limited research has evaluated them. The 2012 International Council for Standardization in Haematology (ICSH) recommends a schistocyte quantitation of 1% as a robust cut-off for significance, with the quantitation including helmet, crescent, triangle and keratocyte poikilocytes; and microspherocytes only in the presence of helmets, crescents/triangles, and keratocytes. We aimed to evaluate the relative contribution of these different poikilocytes to schistocyte counting; compare the ICSH method with our proposed method which counts only cells most specific for red cell fragmentation (helmet, crescent and triangular schistocytes); and evaluate inter- and intra-observer agreement. Blood films were sourced from the Australian Snakebite Project, including non-envenomed and envenomed cases, with and without TMA. In blood films across the range of schistocytosis, the predominant poikilocytes present were helmets and crescents. Triangles, keratocytes and microspherocytes were typically only present when ICSH schistocyte count was >1%. With results dichotomised as <1.0% or ≥1.0%, our proposed new method versus the ICSH method showed almost perfect agreement [observed agreement 95%, Cohen's kappa (κ)=0.84, SE 0.04, 95% CI 0.76–0.92, p<0.005]. Inter-observer strength of agreement for our method was moderate (Fleiss' κ for comparisons between three non-unique microscopists κ=0.50, SE 0.05, 95% CI 0.41–0.59, p<0.005). Intra-observer reproducibility assessed in two microscopists ranged from substantial (Cohen's κ=0.71, SE 0.08, 95% CI 0.55–0.86, p<0.005) to borderline almost perfect agreement (Cohen's κ=0.81, SE 0.07, 95% CI 0.68–0.93, p<0.005). Schistocyte quantitation using our new method is simpler than the 2012 ICSH method and had almost perfect agreement. Our finding of moderate inter-observer agreement in quantitating helmet, triangle and crescent schistocytes is applicable to both the ICSH and our newly proposed method. This finding underscores the importance of clinicopathological correlation and repeated examinations in the context of a clinically suspected TMA.

Published
2021
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8. Stable and changing characteristics of high-level handball as evidenced from World Men's Championships.

Author

PANAGIOTIS, MELETAKOS G., KONSTANTINOS, NOUTSOS S., and IOANNIS, BAYIOS A.

Abstract

The systematic observation and notational analysis of games helped the development of research in this particular field. The aim of the study is to present the model of play in high level Men's handball, taking a quantitative approach for the teams ranked in the first four positions, out of the total twenty four teams that participated in the eight consecutive World Championships from 2005 to 2019, in order to seek differentiation over the years as well as highlight differences between the teams. The sample consisted of 300 matches, where all the relevant statistics for each team were recorded. Results showed that the total number of new offenses and shots per game seem to have had a significant downward trend over the years, from 2005 to 2019, which however was not reflected by a collateral drop in goals scored. Over the years, statistically significant fluctuations can be seen in the percentage distribution of goals for 6m, 9m and breakthroughs. In the last three championships, the number of goals scored for 6m equaled the ones scored for the 9m. No significant differences were observed over the years for the court players and goalkeeper efficacies, where the specific indices remain high and stable .The stepwise logistic regression model revealed that the court players' breakthrough efficacy, the goalkeeper's efficacy from 6m shots and the number of steals per game can discriminate the teams that won the first place from teams that ranked fourth. Decision making leaders must choose players who are able to support the strategies and tactics that the coach decides dependent on the circumstances and game development. [ABSTRACT FROM AUTHOR]

Published
2020
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9. Workplace locations of 2011-2017 Northern Territory Medical Program graduates.

Author

Campbell, Narelle, Kennedy, Emma, Rissel, Chris, Gill, Eliza, Bergin, Shirley, Noutsos, Tina, and O'Donoghue, Olivia

Abstract

The article informs about Workplace locations of 2011-2017 Northern Territory Medical Program graduates. Topics include Data are from administrative records of student progression and publicly available data of medical registration with the Australian Health Practitioner Regulation Agency (AHPRA); and graduates working in the Northern Territory (NT) supports the value of locally trained medical practitioners.

Published
2021
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10. Morphological characteristics of adolescent elite female handball and volleyball players.

Author

KONSTANTINOS, NOUTSOS S., PANAGIOTIS, MELETAKOS G., and IOANNIS, BAYIOS A.

Abstract

The aim of the current study is to compare morphological characteristics of adolescent elite female handball and volleyball players and to investigate probable differences between them. The sample of the current study consists of athletes from women's national handball teams (n=32, age=17.8±1.1 years, body height 166.6±4.5 cm, body mass 65.0±5.4 kg) and volleyball (n=16, age=18.0±1.4 years, body height 176.5±5.7 cm, body mass 68.1±7.4 kg). The measurements included five skin folds thicknesses (biceps, triceps, subscapular, suprailiac and calf), three circumferences [calf and biceps girth (relaxed and tensed)] end two widths (femur, humerus). In the initial somatometric parameters, the athletes exhibit higher performance triceps (p<0.001), subscapular (p<0.001) skinfold (mm) and biceps girth (relaxed) (cm) while volleyball players exhibit body height (cm) (p<0.05) and humeral diameter (cm) (p<0.05). In the secondary parameters, handball players express statistically significant body mass indices (kg/m²) (p<0.05), body fat (%) (p<0.002), sum of 5 skinfold (mm) (p<0.001), while volleyball players express fat free mass (kg) (p<0.001). The handball players' somatotype is taken to be a mesomorph-endomorph (3.9-3.8-1.7) with a much greater component in endomorphy (p<0.001), mesomorphy (p<0.001), and SDM (p<0.001), while volleyball players were taken as balanced endomorph (3.3- 2.6-3.1) with a much greater component of ectomorphy (p<0.001), ... SAM (p<0.006). In conclusion, the differences may probably be due to the specific training of the female athletes. [ABSTRACT FROM AUTHOR]

Published
2019
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11. The Northern Territory Medical Program - growing our own in the NT.

Author

Worley, Paul, Lowe, Michael, Notaras, Leonard, Strasser, Sarah, Kidd, Michael, Slee, Mark, Williams, Rhys, Noutsos, Tina, and Wakerman, John

Abstract

Context: The Northern Territory (NT) is characterised by major health inequalities. A high proportion of the population is Indigenous, with poor socioeconomic conditions and a high burden of disease. The small NT population – 1% of the total Australian population – is dispersed over one-sixth of Australia’s land mass. Given this very low population density and the geographical isolation of many small communities, access to services is often difficult. Medical workforce recruitment and retention have been persistent problems. Prior to 2011, NT residents who aspired to study medicine had to leave the NT. This was the only Australian state or territory that did not have the capacity for students to complete an entire medical degree within the jurisdiction. This article describes the development, implementation and outcomes of the Northern Territory Medical Program (NTMP), which commenced in Darwin in 2011. This was a major development of the Flinders University distributed program, which aimed to develop the medical workforce for the challenging NT environment. Issues: Based on evidence regarding the importance of selection in achieving rural workforce outcomes, and a national priority to graduate more Indigenous Australian doctors, NT residents and Indigenous applicants to the NTMP were prioritised in the selection process. Aspiring doctors would not now have to move interstate to study. The curriculum of Flinders University, based in Adelaide, South Australia, would be contextualised to the NT. The NTMP was developed and implemented in collaboration with Charles Darwin University, the major university in the NT. Lessons learned: Some of the lessons learned may be useful to others contemplating the delivery of a distributed program that includes a full medical program in a remote area. These include: 1. Leadership at the highest levels of the university is crucial. Expect faculty turnover and avoid single person vulnerabilities. 2. 3. Actively engage local clinicians. Ensure a strong focus on new or alternative selection processes that are able to predict progression. 4. Provide preparatory skills and support for students, especially Indigenous students, with non-science backgrounds. 5. Appreciate and accommodate the community and family pressures experienced by some Indigenous students. 6. Anticipate that the first pioneering cohort of students will not be typical of future cohorts, and work with them to adapt the curriculum, teaching and selection methods. 7. Whilst exemplary telecommunications are needed, some elements of the curriculum will be able to be delivered far better locally than at the larger campus. 8. Do not underestimate the level of student and staff support required both locally and centrally. Develop a ‘network’ rather than a ‘hub and spoke’ model. 9. The network may include multiple dispersed placement sites, requiring infrastructure, staffing and ongoing support. 10. The ‘new kid’ will mean the ‘older sibling’ will change for the better and use the small size and agility to explore innovations. 11. Focus on the goals. We wanted to contribute to improved economic, social and health outcomes for NT residents by developing an appropriately prepared medical workforce, thereby eliminating the need to recruit doctors from interstate and overseas, and by graduating more Indigenous doctors – potential medical leaders for Australia. 12. Build your expectation for success based on past successes in innovation. Flinders University was able to build on its experience in developing the first 4-year medical program in Australia. [ABSTRACT FROM AUTHOR]

Published
2019
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12. Performance indicators and competition ranking in Women's and Men's World Handball Championship 2017.

Author

Konstantinos, Noutsos S., Elissavet, Rousanoglou N., Panagiotis, Meletakos G., Ioannis, Bayios A., and Konstantinos, Boudolos D.

Abstract

The study aims to evaluate the efficacy of specific performance indicators in the final competition ranking of national handball teams, of different competitive levels on a world scale. Also, an attempt was made to portray to what degree the examined performance indicators influence game performance. Additionally, an attempt was made to clarify to what degree the observed indices affect the final ranking. The collected data comprised eight indices: a) Age (years) b) Body Height (cm) c) Body Mass (kg) d) International Matches played e) International Goals scored f) Total Shots per player g) Total goals per player h) Team Scoring Efficiency (%). These indices were grouped into: i) Anthropometric index that includes, a) Body Height (cm) b) Body Mass (kg) (ii) Game experience indices that include a) Age (years) b) International Matches played c) International Goals scored, (iii) Performance efficacy indices that include a) Total Shots per player b) Total goals per player c) Team Scoring Efficiency (%). Descriptive statistics were used (mean, standard deviation), a comparison between the group with ONE-WAY-ANOVA followed by non-parametric correlation Spearman's rho and Factor analysis. Placing the indices in order of hierarchy by our results, the most critical parameters in the ranking of the men's teams is game experience and anthropometric index that influence the final team ranking. As far as the women's groups are concerned, the index that played a vital role and affects the final ranking, in order of importance, are performance efficacy, game experience indices, follow anthropometrically and finally Team Scoring Efficiency. [ABSTRACT FROM AUTHOR]

Published
2018
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13. Recurrent and Refractory Hemophagocytic Lymphohistiocytosis in an Elderly. Role of Immune Aberration Due to Myeloid Gene Mutation

Author

Ramamoorthy, Suthanthira kannan, Noutsos, Tina, Wei, David, Yasmin Laidman, Alexandra, and Szabo, Ferenc

Abstract

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal hyper-inflammatory disease induced by aberrant immune activation and subsequent proliferation of macrophages, histiocytes and T-helper cells. In this abstract we present a case of HLH, which relapsed twice despite ongoing treatment, and we hypothesize on possible causes and mechanisms.

Published
2020
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15. Genomes of 13 domesticated and wild rice relatives highlight genetic conservation, turnover and innovation across the genus Oryza

Author

Stein, Joshua C., Yu, Yeisoo, Copetti, Dario, Zwickl, Derrick J., Zhang, Li, Zhang, Chengjun, Chougule, Kapeel, Gao, Dongying, Iwata, Aiko, Goicoechea, Jose Luis, Wei, Sharon, Wang, Jun, Liao, Yi, Wang, Muhua, Jacquemin, Julie, Becker, Claude, Kudrna, Dave, Zhang, Jianwei, Londono, Carlos E. M., Song, Xiang, Lee, Seunghee, Sanchez, Paul, Zuccolo, Andrea, Ammiraju, Jetty S. S., Talag, Jayson, Danowitz, Ann, Rivera, Luis F., Gschwend, Andrea R., Noutsos, Christos, Wu, Cheng-chieh, Kao, Shu-min, Zeng, Jhih-wun, Wei, Fu-jin, Zhao, Qiang, Feng, Qi, El Baidouri, Moaine, Carpentier, Marie-Christine, Lasserre, Eric, Cooke, Richard, Rosa Farias, Daniel da, da Maia, Luciano Carlos, dos Santos, Railson S., Nyberg, Kevin G., McNally, Kenneth L., Mauleon, Ramil, Alexandrov, Nickolai, Schmutz, Jeremy, Flowers, Dave, Fan, Chuanzhu, Weigel, Detlef, Jena, Kshirod K., Wicker, Thomas, Chen, Mingsheng, Han, Bin, Henry, Robert, Hsing, Yue-ie C., Kurata, Nori, de Oliveira, Antonio Costa, Panaud, Olivier, Jackson, Scott A., Machado, Carlos A., Sanderson, Michael J., Long, Manyuan, Ware, Doreen, and Wing, Rod A.

Abstract

The genus Oryzais a model system for the study of molecular evolution over time scales ranging from a few thousand to 15 million years. Using 13 reference genomes spanning the Oryzaspecies tree, we show that despite few large-scale chromosomal rearrangements rapid species diversification is mirrored by lineage-specific emergence and turnover of many novel elements, including transposons, and potential new coding and noncoding genes. Our study resolves controversial areas of the Oryzaphylogeny, showing a complex history of introgression among different chromosomes in the young ‘AA’ subclade containing the two domesticated species. This study highlights the prevalence of functionally coupled disease resistance genes and identifies many new haplotypes of potential use for future crop protection. Finally, this study marks a milestone in modern rice research with the release of a complete long-read assembly of IR 8 ‘Miracle Rice’, which relieved famine and drove the Green Revolution in Asia 50 years ago.

Published
2018
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17. Pulsar timing for the Fermigamma-ray space telescope *

Author

Smith, D. A., Guillemot, L., Camilo, F., Cognard, I., Dumora, D., Espinoza, C., Freire, P. C. C., Gotthelf, E. V., Harding, A. K., Hobbs, G. B., Johnston, S., Kaspi, V. M., Kramer, M., Livingstone, M. A., Lyne, A. G., Manchester, R. N., Marshall, F. E., McLaughlin, M. A., Noutsos, A., Ransom, S. M., Roberts, M. S. E., Romani, R. W., Stappers, B. W., Theureau, G., Thompson, D. J., Thorsett, S. E., Wang, N., Weltevrede, P., Smith, D. A., Guillemot, L., Camilo, F., Cognard, I., Dumora, D., Espinoza, C., Freire, P. C. C., Gotthelf, E. V., Harding, A. K., Hobbs, G. B., Johnston, S., Kaspi, V. M., Kramer, M., Livingstone, M. A., Lyne, A. G., Manchester, R. N., Marshall, F. E., McLaughlin, M. A., Noutsos, A., Ransom, S. M., Roberts, M. S. E., Romani, R. W., Stappers, B. W., Theureau, G., Thompson, D. J., Thorsett, S. E., Wang, N., and Weltevrede, P.

Abstract

We describe a comprehensive pulsar monitoring campaign for the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope(formerly GLAST). The detection and study of pulsars in gamma rays give insights into the populations of neutron stars and supernova rates in the Galaxy, into particle acceleration mechanisms in neutron star magnetospheres, and into the “engines” driving pulsar wind nebulae. LAT's unprecedented sensitivity between 20 MeV and 300 GeV together with its 2.4 sr field-of-view makes detection of many gamma-ray pulsars likely, justifying the monitoring of over two hundred pulsars with large spin-down powers. To search for gamma-ray pulsations from most of these pulsars requires a set of phase-connected timing solutions spanning a year or more to properly align the sparse photon arrival times. We describe the choice of pulsars and the instruments involved in the campaign. Attention is paid to verifications of the LAT pulsar software, using for example giant radio pulses from the Craband from PSR B1937+21recorded at Nançay, and using X-ray data on PSR J0218+4232from XMM-Newton. We demonstrate accuracy of the pulsar phase calculations at the microsecond level.

Published
2008
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18. Discovery of two candidate pulsar wind nebulae in very-high-energy gamma rays

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, S., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Ruppel, J., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., O'C. Drury, L., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, S., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Ruppel, J., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Context.We present the discovery of two very-high-energy γ-ray sources in an ongoing systematic search for emission above 100 GeV from pulsar wind nebulae in survey data from the HESS telescope array.

Published
2007
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19. Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232with HESS and broadband characterisation

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Context.The blazar 1ES 1101-232was observed with the High Energy Stereoscopic System (HESS) of Atmospheric Cherenkov Telescopes (ACT) in 2004 and 2005, for a live time of 43 h. VHE (E> 1011eV) γ-rays were detected for the first time from this object.

Published
2007
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20. Discovery of a point-like very-high-energy γ-ray source in Monoceros

Author

Aharonian, F. A., Akhperjanian, A. G., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Ruppel, J., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Moriguchi, Y., Fukui, Y., Aharonian, F. A., Akhperjanian, A. G., Bazer-Bachi, A. R., Behera, B., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Fiasson, A., Förster, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pedaletti, G., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Ruppel, J., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Moriguchi, Y., and Fukui, Y.

Abstract

Aims.The complex Monoceros Loop SNR/Rosette Nebula region contains several potential sources of very-high-energy (VHE) γ-ray emission and two as yet unidentified high-energy EGRET sources. Sensitive VHE observations are required to probe acceleration processes in this region.

Published
2007
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21. Detection of extended very-high-energy γ-ray emission towards the young stellar cluster Westerlund 2

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.Results from γ-ray observations by the HESS telescope array in the direction of the young stellar cluster Westerlund 2 are presented.

Published
2007
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22. Search for pulsed VHE gamma-ray emission from young pulsars with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Eifert, T., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Manchester, R. N., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schmidt, F., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Boutelier, T., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Eifert, T., Emmanoulopoulos, D., Espigat, P., Farnier, C., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Manchester, R. N., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Petrucci, P.-O., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schmidt, F., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.We present the results of a search for pulsed very-high-energy (VHE) γ-ray emission from young pulsars using data taken with the HESS imaging atmospheric Cherenkov telescope system.

Published
2007
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23. Primary particle acceleration above 100 TeV in the shell-type supernova remnant RX J1713.7-3946with deep HESS observations

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brion, E., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Coignet, G., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Hoppe, S., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Kerschhaggl, M., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Lamanna, G., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Olive, J.-P., Orford, K. J., Osborne, J. L., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Ranchon, S., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rosier-Lees, S., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Schwemmer, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tam, P. H., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.We present deep HESS observations of the supernova remnant (SNR) RX J1713.7-3946. Combining data of three years – from 2003 to 2005 – we obtain significantly increased statistics and energy coverage as compared to earlier 2003 and 2004 results.

Published
2007
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24. 3.9 day orbital modulation in the TeV γ-ray flux and spectrum from the X-ray binary LS 5039

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., O'C. Drury, L., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., O'C. Drury, L., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.LS 5039 is a High Mass X-ray Binary (HMXRB) comprising a compact object in an eccentric 3.9 day orbit around a massive O6.5V star. Observations at energies above 0.1 TeV (1011eV) by the High Energy Stereoscopic System (HESS) in 2004 revealed that LS 5039 is a source of Very High Energy (VHE) γ-rays and hence, is able to accelerate particles to multi-TeV energies. Deeper observations by HESS were carried out in 2005 in an effort to probe further the high energy astrophysics taking place. In particular, we have searched for orbital modulation of the VHE γ-ray flux, which if detected, would yield new information about the complex variation in γ-ray absorption and production within X-ray binary systems.

Published
2006
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25. Energy dependent γ-ray morphology in the pulsar wind nebula HESS J1825–137

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., Moulin, E., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.We present results from deep γ-ray observations of the Galactic pulsar wind nebula HESS J1825–137performed with the HESS array.

Published
2006
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26. Observations of the Crab nebula with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Context.The Crab nebula was observed with the HESS stereoscopic Cherenkov-telescope array between October 2003 and January 2005 for a total of 22.9 h (after data quality selection). This period of time partly overlapped with the commissioning phase of the experiment; observations were made with three operational telescopes in late 2003 and with the complete 4 telescope array in January–February 2004 and October 2004–January 2005.

Published
2006
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27. Discovery of the two “wings” of the Kookaburra complex in VHE γ-rays with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, S., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fiasson, A., Fontaine, G., Funk, S., Funk, S., Füßling, M., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Kendziorra, E., Khélifi, B., Komin, Nu., Konopelko, A., Kosack, K., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., Maurin, G., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Santangelo, A., Saugé, L., Schlenker, S., Schlickeiser, R., Schröder, R., Schwanke, U., Schwarzburg, S., Shalchi, A., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

Aims.Search for Very High Energy γ-ray emission in the Kookaburra complex through observations with the HESS array.

Published
2006
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28. Discovery of very high energy γ-ray emission from the BL Lacertae object H 2356-309 with the HESS Cherenkov telescopes

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Ferrero, E., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

The extreme synchrotron BL Lac object H 2356-309, located at a redshift of $z = 0.165$, was observed from June to December 2004 with a total exposure of ≈40 h live-time with the HESS (High Energy Stereoscopic System) array of atmospheric-Cherenkov telescopes (ACTs). Analysis of this data set yields, for the first time, a strong excess of 453 γ-rays (10 standard deviations above background) from H 2356-309, corresponding to an observed integral flux above 200 GeV of I(>200 GeV) = (4.1 ±0.5) $\times$10-12cm-2s-1(statistical error only). The differential energy spectrum of the source between 200 GeV and 1.3 TeV is well-described by a power law with a normalisation (at 1 TeV) of N0= (4.1 ±0.5) $\times$10-13cm-2s-1TeV-1and a photon index of Γ= $3.09\,\pm\,0.24_\mathrm{stat}\,\pm\,0.10_\mathrm{sys}$. H 2356-309 is one of the most distant BL Lac objects detected at very-high-energy γ-rays so far. Results from simultaneous observations from ROTSE-III (optical), RXTE (X-rays) and NRT (radio) are also included and used together with the HESS data to constrain a single-zone homogeneous synchrotron self-Compton (SSC) model. This model provides an adequate fit to the HESS data when using a reasonable set of model parameters.

Published
2006
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29. A detailed spectral and morphological study of the gamma-ray supernova remnant RX J1713.7–3946with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Klages, S., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Klages, S., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., and Wagner, S. J.

Abstract

Aims.We present results from deep observations of the Galactic shell-type supernova remnant (SNR) RX J1713.7-3946(also known as G347.3-0.5) conducted with the complete HESS array in 2004.Methods.Detailed morphological and spatially resolved spectral studies reveal the very-high-energy (VHE – Energies $E > 100$GeV) gamma-ray aspects of this object with unprecedented precision. Since this is the first in-depth analysis of an extended VHE gamma-ray source, we present a thorough discussion of our methodology and investigations of possible sources of systematic errors.Results.Gamma rays are detected throughout the whole SNR. The emission is found to resemble a shell structure with increased fluxes from the western and northwestern parts. The differential gamma-ray spectrum of the whole SNR is measured over more than two orders of magnitude, from 190 GeV to 40 TeV, and is rather hard with indications for a deviation from a pure power law at high energies. Spectra have also been determined for spatially separated regions of RX J1713.7-3946. The flux values vary by more than a factor of two, but no significant change in spectral shape is found. There is a striking correlation between the X-ray and the gamma-ray image. Radial profiles in both wavelength regimes reveal the same shape almost everywhere in the region of the SNR.Conclusions.The VHE gamma-ray emission of RX J1713.7-3946is phenomenologically discussed for two scenarios, one where the gamma rays are produced by VHE electrons via Inverse Compton scattering and one where the gamma rays are due to neutral pion decay from proton-proton interactions. In conjunction with multi-wavelength considerations, the latter case is favoured. However, no decisive conclusions can yet be drawn regarding the parent particle population dominantly responsible for the gamma-ray emission from RX J1713.7-3946.

Published
2006
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30. Evidence for VHE γ-ray emission from the distant BL Lac PG 1553+113

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

The high-frequency peaked BL Lac PG 1553+113 was observed in 2005 with the HESS stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia. Using the HESS standard analysis, an excess was measured at the 4.0σlevel in these observations (7.6 hours live time). Three alternative, lower-threshold analyses yield >5σexcesses. The observed integral flux above 200 GeV is $(4.8\pm1.3_{\rm stat}\pm1.0_{\rm syst})\times10^{-12}$cm-2s-1, and shows no evidence for variability. The measured energy spectrum is characterized by a very soft power law (photon index of $\Gamma=4.0\pm0.6$). Although the redshift of PG 1553+113 is unknown, there are strong indications that it is greater than $z=0.25$and possibly larger than $z=0.78$. The observed spectrum is interpreted in the context of VHE γ-ray absorption by the Extragalactic Background Light, and is used to place an upper limit on the redshift of $z<0.74$.

Published
2006
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31. First detection of a VHE gamma-ray spectral maximum from a cosmic source: HESS discovery of the Vela X nebula

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Epinat, B., Espigat, P., Feinstein, F., Ferrero, E., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Ward, M., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Bühler, R., Büsching, I., Carrigan, S., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Egberts, K., Emmanoulopoulos, D., Epinat, B., Espigat, P., Feinstein, F., Ferrero, E., Fontaine, G., Funk, Seb., Funk, S., Gallant, Y. A., Giebels, B., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, D., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nedbal, D., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schwanke, U., Sol, H., Spangler, D., Spanier, F., Steenkamp, R., Stegmann, C., Superina, G., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., van Eldik, C., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., and Ward, M.

Abstract

The Vela supernova remnant (SNR) is a complex region containing a number of sources of non-thermal radiation. The inner section of this SNR, within 2 degrees of the pulsar PSR B0833-45, has been observed by the HESS γ-ray atmospheric Cherenkov detector in 2004 and 2005. A strong signal is seen from an extended region to the south of the pulsar, within an integration region of radius $0.8\ensuremath{^{\circ}}$around the position ($\rm \alpha = 08^{h} 35^{m} 00^{s}$, $\delta = -45\ensuremath{^{\circ}}36\arcmin$J2000.0). The excess coincides with a region of hard X-ray emission seen by the ROSAT and ASCA satellites. The observed energy spectrum of the source between 550 GeV and 65 TeV is well fit by a power law function with photon index $\Gamma = 1.45 \pm 0.09\ensuremath{_{{\rm stat}}}\ \pm 0.2\ensuremath{_{{\rm sys}}}$and an exponential cutoff at an energy of $13.8 \pm 2.3\ensuremath{_{{\rm stat}}}\ \pm 4.1\ensuremath{_{{\rm sys}}}$TeV. The integral flux above 1 TeV is $(1.28 \pm 0.17\ensuremath{_{{\rm stat}}}\ \pm 0.38\ensuremath{_{{\rm sys}}}) \times 10^{-11}\ \ensuremath{{\rm cm}^{-2}\,{\rm s}^{-1}}$. This result is the first clear measurement of a peak in the spectral energy distribution from a VHE γ-ray source, likely related to inverse Compton emission. A fit of an Inverse Compton model to the HESS spectral energy distribution gives a total energy in non-thermal electrons of ~$2 \times 10^{45}$erg between 5 TeV and 100 TeV, assuming a distance of 290 parsec to the pulsar. The best fit electron power law index is 2.0, with a spectral break at 67 TeV.

Published
2006
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32. Multi-wavelength observations of PKS 2155-304 with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J ., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J ., and Wagner, S. J.

Abstract

The High Energy Stereoscopic System (HESS) has observed the high-frequency peaked BL Lac object PKS 2155-304 in 2003 between October 19 and November 26 in Very High Energy (VHE) γ-rays ($E\geq 160\,\rm GeV$for these observations). Observations were carried out simultaneously with the Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer satellite (RXTE), the Robotic Optical Transient Search Experiment (ROTSE) and the Nançay decimetric radiotelescope (NRT). Intra-night variability is seen in the VHEband, the source being detected with a high significance on each night it was observed. Variability is also found in the X-ray and optical bands on kilosecond timescales, along with flux-dependent spectral changes in the X-rays. A transient X-ray event with a 1500 s timescale is detected, making this the fastest X-ray flare seen in this object. No correlation can be established between the X-ray and the γ-ray fluxes, or any of the other wavebands, over the small range of observed variability. The average HESS spectrum shows a very soft power law shape with a photon index of $3.37 \pm 0.07_{\rm stat} \pm 0.10_{\rm sys}$. The energy outputs in the 2–$10\,\rm keV$and in the VHE γ-ray range are found to be similar, with the X-rays and the optical fluxes at a level comparable to some of the lowest historical measurements, indicating that PKS 2155-304 was in a low or quiescent state during the observations. Both a leptonic and a hadronic model are used to derive source parameters from these observations. These parameters are found to be sensitive to the model of Extragalactic Background Light (EBL) that attenuates the VHE signal at this source's redshift ($z=0.117$).

Published
2005
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33. A possible association of the new VHE γ-ray source HESS J1825–137 with the pulsar wind nebula G 18.0–0.7

Author

Aharonian, F. A., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Aharonian, F. A., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., and Wagner, S. J.

Abstract

We report on a possible association of the recently discovered very high-energy γ-ray source HESS J1825–137 with the pulsar wind nebula (commonly referred to as G 18.0–0.7) of the $2.1\times 10^{4}$year old Vela-like pulsar PSR B1823–13. HESS J1825–137 was detected with a significance of 8.1σin the Galactic Plane survey conducted with the HESS instrument in 2004. The centroid position of HESS J1825–137 is offset by 11´  south of the pulsar position. XMM-Newtonobservations have revealed X-ray synchrotron emission of an asymmetric pulsar wind nebula extending to the south of the pulsar. We argue that the observed morphology and TeV spectral index suggest that HESS J1825–137 and G 18.0–0.7 may be associated: the lifetime of TeV emitting electrons is expected to be longer compared to the XMM-NewtonX-ray emitting electrons, resulting in electrons from earlier epochs (when the spin-down power was larger) contributing to the present TeV flux. These electrons are expected to be synchrotron cooled, which explains the observed photon index of ~2.4, and the longer lifetime of TeV emitting electrons naturally explains why the TeV nebula is larger than the X-ray size. Finally, supernova remnant expansion into an inhomogeneous medium is expected to create reverse shocks interacting at different times with the pulsar wind nebula, resulting in the offset X-ray and TeV γ-ray morphology.

Published
2005
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34. Discovery of the binary pulsar PSR B1259-63in very-high-energy gamma rays around periastron with HESS

Author

Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Johnston, S., Khélifi, B., Kirk, J. G., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Martineau-Huynh, O., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Skjæraasen, O., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Johnston, S., Khélifi, B., Kirk, J. G., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Martineau-Huynh, O., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Skjæraasen, O., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., and Wagner, S. J.

Abstract

We report the discovery of very-high-energy (VHE) γ-ray emission of the binary system PSR B1259-63/SS 2883of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the HESS experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a γ-ray signal from the binary system was detected with a total significance above $13\sigma$. The flux was found to vary significantly on timescales of days which makes PSR B1259-63the first variable galactic source of VHE γ-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law $F_0(E/1\,\rm TeV)^{-\Gamma}$with a photon index $\Gamma = 2.7\pm0.2_\mathrm{stat}\pm0.2_\mathrm{sys}$and flux normalisation $F_0 = (1.3 \pm 0.1_\mathrm{stat} \pm 0.3_\mathrm{sys}) \times 10^{-12}\,\rm TeV^{-1}\,\rm cm^{-2}\,\rm s^{-1}$. This detection of VHE γ-rays provides unambiguous evidence for particle acceleration to multi-TeV energies in the binary system. In combination with coeval observations of the X-ray synchrotron emission by the RXTEand INTEGRALinstruments, and assuming the VHE γ-ray emission to be produced by the inverse Compton mechanism, the magnetic field strength can be directly estimated to be of the order of 1 G.

Published
2005
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35. A search for very high energy γ-ray emission from the starburst galaxy NGC 253 with HESS

Author

Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Bernlöhr, K., Boisson, C., Bolz, O., Borrel, V., Braun, I., Breitling, F., Brown, A. M., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Dickinson, H. J., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., Jacholkowska, A., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martin, J. M., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Spangler, D., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., and Wagner, S. J.

Abstract

We present the result of 28 h of observations of the nearby starburst galaxy NGC 253 with the HESS detector in 2003. We find no evidence for very high energy γ-ray emission from this object. Gamma-ray emission above 400 GeV from NGC 253 had been reported by the CANGAROO collaboration in 2002. From the HESS data we derive upper limits on the flux above 300 GeV of $1.9\,\times\,10^{-12}$photons cm-2s-1for a point-like source and $6.3\,\times\,10^{-12}$photons cm-2s-1for a source of radius 0.5° as reported by CANGAROO, both at a confidence level of 99%. These upper limits are inconsistent with the spectrum reported by CANGAROO. The expected very high energy γ-ray emission from this object is discussed in the framework of a galactic wind propagation model.

Published
2005
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36. Discovery of extended VHE gamma-ray emission from the asymmetric pulsar wind nebula in MSH 15-52with HESS

Author

Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Emmanoulopoulos, D., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Fuchs, Y., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Glicenstein, J. F., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine-Goumard, M., Leroy, N., Lohse, T., Martineau-Huynh, O., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Völk, H. J., and Wagner, S. J.

Abstract

The Supernova Remnant MSH 15-52has been observed in very high energy (VHE) γ-rays using the HESS 4-telescope array located in Namibia. A γ-ray signal is detected at the 25 sigma level during an exposure of 22.1 h live time. The image reveals an elliptically shaped emission region around the pulsar PSR B1509–58, with semi-major axis ~$6'$in the NW-SE direction and semi-minor axis ~$2'$. This morphology coincides with the diffuse pulsar wind nebula as observed at X-ray energies by ROSAT. The overall energy spectrum from 280 GeV up to 40 TeV can be fitted by a power law with photon index $\Gamma=2.27\pm0.03_{\textrm {\scriptsize \,stat}}\pm 0.20_{\textrm{\scriptsize \,syst}}$. The detected emission can be plausibly explained by inverse Compton scattering of accelerated relativistic electrons with soft photons.

Published
2005
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37. Very high energy gamma rays from the composite SNR G 0.9+0.1

Author

Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Borgmeier, C., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine, M., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Visser, B., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Boisson, C., Bolz, O., Borgmeier, C., Braun, I., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Dubus, G., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Goret, P., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemière, A., Lemoine, M., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Terrier, R., Théoret, C. G., Tluczykont, M., Vasileiadis, G., Venter, C., Vincent, P., Visser, B., Völk, H. J., and Wagner, S. J.

Abstract

Very high energy (>100 GeV) gamma-ray emission has been detected for the first time from the composite supernova remnant G 0.9+0.1 using the HESS  instrument. The source is detected with a significance of ≈$13\sigma$, and a photon flux above 200 GeV of ($5.7\pm0.7_{\rm stat}\pm1.2_{\rm sys})\times10^{-12}$cm-2s-1, making it one of the weakest sources ever detected at TeV energies. The photon spectrum is compatible with a power law (${\rm d}N/{\rm d}E \propto E^{-\Gamma}$) with photon index $\Gamma = 2.40\pm0.11_{\rm stat}\pm0.20_{\rm sys}$. The gamma-ray emission appears to originate in the plerionic core of the remnant, rather than the shell, and can be plausibly explained as inverse Compton scattering of relativistic electrons.

Published
2005
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38. H.E.S.S. observations of PKS 2155-304

Author

Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Bolz, O., Boisson, C., Borgmeier, C., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chitnis, V. R., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L.O'C., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Goret, P., Guy, J., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemoine, M., Lemière, A., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pohl, M., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rivoal, M., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Théoret, C. G., Tluczykont, M., van der Walt, D. J., Vasileiadis, G., Vincent, P., Visser, B., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Bolz, O., Boisson, C., Borgmeier, C., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chitnis, V. R., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L.O'C., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y. A., Giebels, B., Gillessen, S., Goret, P., Guy, J., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemoine, M., Lemière, A., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pohl, M., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rivoal, M., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Théoret, C. G., Tluczykont, M., van der Walt, D. J., Vasileiadis, G., Vincent, P., Visser, B., Völk, H. J., and Wagner, S. J.

Abstract

The high-frequency peaked BL Lac PKS 2155-304 at redshift $z=0.117$has been detected with high significance (~45σ) at energies greater than 160 GeV, using the H.E.S.S. stereoscopic array of imaging air-Cherenkov telescopes in Namibia. A strong signal is found in each of the data sets corresponding to the dark periods of July and October, 2002, and June–September, 2003. The observed flux of VHE gamma rays shows variability on time scales of months, days, and hours. The monthly-averaged integral flux above 300 GeV varies between 10% and 60% of the flux observed from the Crab Nebula. Energy spectra are measured for these individual periods of data taking and are characterized by a steep power law with a time-averaged photon index of $\Gamma=3.32\pm0.06$. An improved $\chi^2$per degree of freedom is found when either a power law with an exponential cutoff energy or a broken power law are fit to the time-averaged energy spectrum. However, the significance of the improvement is marginal (~2σ). The suggested presence of features in the energy spectrum may be intrinsic to the emission from the blazar, or an indication of absorption of TeV gamma rays by the extragalactic infrared background light.

Published
2005
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39. Very high energy gamma rays from the direction of Sagittarius A*

Author

Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Bolz, O., Boisson, C., Borgmeier, C., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chitnis, V. R., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y., Giebels, B., Gillessen, S., Goret, P., Guy, J., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemoine, M., Lemière, A., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pohl, M., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rivoal, M., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Théoret, C. G., Tluczykont, M., van der Walt, D. J., Vasileiadis, G., Vincent, P., Visser, B., Völk, H. J., Wagner, S. J., Aharonian, F., Akhperjanian, A. G., Aye, K.-M., Bazer-Bachi, A. R., Beilicke, M., Benbow, W., Berge, D., Berghaus, P., Bernlöhr, K., Bolz, O., Boisson, C., Borgmeier, C., Breitling, F., Brown, A. M., Bussons Gordo, J., Chadwick, P. M., Chitnis, V. R., Chounet, L.-M., Cornils, R., Costamante, L., Degrange, B., Djannati-Ataï, A., Drury, L. O'C., Ergin, T., Espigat, P., Feinstein, F., Fleury, P., Fontaine, G., Funk, S., Gallant, Y., Giebels, B., Gillessen, S., Goret, P., Guy, J., Hadjichristidis, C., Hauser, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holleran, M., Horns, D., de Jager, O. C., Jung, I., Khélifi, B., Komin, Nu., Konopelko, A., Latham, I. J., Le Gallou, R., Lemoine, M., Lemière, A., Leroy, N., Lohse, T., Marcowith, A., Masterson, C., McComb, T. J. L., de Naurois, M., Nolan, S. J., Noutsos, A., Orford, K. J., Osborne, J. L., Ouchrif, M., Panter, M., Pelletier, G., Pita, S., Pohl, M., Pühlhofer, G., Punch, M., Raubenheimer, B. C., Raue, M., Raux, J., Rayner, S. M., Redondo, I., Reimer, A., Reimer, O., Ripken, J., Rivoal, M., Rob, L., Rolland, L., Rowell, G., Sahakian, V., Saugé, L., Schlenker, S., Schlickeiser, R., Schuster, C., Schwanke, U., Siewert, M., Sol, H., Steenkamp, R., Stegmann, C., Tavernet, J.-P., Théoret, C. G., Tluczykont, M., van der Walt, D. J., Vasileiadis, G., Vincent, P., Visser, B., Völk, H. J., and Wagner, S. J.

Abstract

We report the detection of a point-like source of very high energy (VHE) γ-rays coincident within $1'$of Sgr A*, obtained with the HESS array of Cherenkov telescopes. The γ-rays exhibit a power-law energy spectrum with a spectral index of $-2.2 \pm 0.09 \pm 0.15$and a flux above the 165 GeV threshold of $(1.82 \pm 0.22) \times 10^{-7}$m-2s-1. The measured flux and spectrum differ substantially from recent results reported in particular by the CANGAROO collaboration.

Published
2004
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40. Band plus algebra preconditioners for two-level Toeplitz systems

Author

Noutsos, D. and Vassalos, P.

Abstract

Abstract: In this paper we are interested in the fast and efficient solution of nm×nm symmetric positive definite ill-conditioned Block Toeplitz with Toeplitz Blocks (BTTB) systems of the form T nm (f)x=b, where the generating function f is a priori known. The preconditioner that we propose and analyze is an extension of the one proposed in (D. Noutsos and P. Vassalos, Comput. Math. Appl., 56 (2008), pp. 1255–1270) and it arises as a product of a Block band Toeplitz matrix and matrices that may belong to any trigonometric matrix algebra. The underlying idea of the proposed scheme is to embody the well known advantages characterizing each component of the product when used alone. As a result we obtain spectral equivalence and a weak clustering of the eigenvalues of the preconditioned matrix around unity, ensuring the convergence of the Preconditioned Conjugate Gradient (PCG) method with a number of iterations independent of the partial dimensions. Finally, we compare our method with techniques already employed in the literature. A wide range of numerical experiments confirms the effectiveness of the proposed procedure and the adherence to the theoretical analysis.

Published
2011
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41. Pulsar timing for the Fermi gamma-ray space telescope

Author

Smith, D., Guillemot, L., Camilo, F., Cognard, I., Dumora, D., Espinoza, C., Freire, P., Gotthelf, E., Harding, A., Hobbs, G., Johnston, S., Kaspi, V., Kramer, M., Livingstone, M., Lyne, A., Manchester, R., Marshall, F., McLaughlin, M., Noutsos, A., Ransom, S., Roberts, M., Romani, R., Stappers, B., Theureau, G., Thompson, D., Thorsett, S., Wang, N., and Weltevrede, P.

Abstract

We describe a comprehensive pulsar monitoring campaign for the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The detection and study of pulsars in gamma rays give insights into the populations of neutron stars and supernova rates in the Galaxy, into particle acceleration mechanisms in neutron star magnetospheres, and into the ?engines? driving pulsar wind nebulae. LAT's unprecedented sensitivity between 20?MeV and 300?GeV together with its 2.4?sr field-of-view makes detection of many gamma-ray pulsars likely, justifying the monitoring of over two hundred pulsars with large spin-down powers. To search for gamma-ray pulsations from most of these pulsars requires a set of phase-connected timing solutions spanning a year or more to properly align the sparse photon arrival times. We describe the choice of pulsars and the instruments involved in the campaign. Attention is paid to verifications of the LAT pulsar software, using for example giant radio pulses from the Crab and from PSR?B1937+21 recorded at Nan?ay, and using X-ray data on PSR?J0218+4232 from XMM-Newton. We demonstrate accuracy of the pulsar phase calculations at the microsecond level.

Published
2008

42. Block band Toeplitz preconditioners derived from generating function approximations: analysis and applications

Author

Noutsos, D., Capizzano, S., and Vassalos, P.

Abstract

We are concerned with the study and the design of optimal preconditioners for ill-conditioned Toeplitz systems that arise from a priori known real-valued nonnegative generating functions f(x,y) having roots of even multiplicities. Our preconditioned matrix is constructed by using a trigonometric polynomial θ(x,y) obtained from Fourier/kernel approximations or from the use of a proper interpolation scheme. Both of the above techniques produce a trigonometric polynomial θ(x,y) which approximates the generating function f(x,y), and hence the preconditioned matrix is forced to have clustered spectrum. As θ(x,y) is chosen to be a trigonometric polynomial, the preconditioner is a block band Toeplitz matrix with Toeplitz blocks, and therefore its inversion does not increase the total complexity of the PCG method. Preconditioning by block Toeplitz matrices has been treated in the literature in several papers. We compare our method with their results and we show the efficiency of our proposal through various numerical experiments.We are concerned with the study and the design of optimal preconditioners for ill-conditioned Toeplitz systems that arise from a priori known real-valued nonnegative generating functions f(x,y) having roots of even multiplicities. Our preconditioned matrix is constructed by using a trigonometric polynomial θ(x,y) obtained from Fourier/kernel approximations or from the use of a proper interpolation scheme. Both of the above techniques produce a trigonometric polynomial θ(x,y) which approximates the generating function f(x,y), and hence the preconditioned matrix is forced to have clustered spectrum. As θ(x,y) is chosen to be a trigonometric polynomial, the preconditioner is a block band Toeplitz matrix with Toeplitz blocks, and therefore its inversion does not increase the total complexity of the PCG method. Preconditioning by block Toeplitz matrices has been treated in the literature in several papers. We compare our method with their results and we show the efficiency of our proposal through various numerical experiments.

Published
2006
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43. A Young-Eidson's type algorithm for complex p-cyclic SOR spectra

Author

Galanis, S., Hadjidimos, A., and Noutsos, D.

Abstract

In a recent work of ours we have solved the problem of the minimization of the spectral radius of the iteration matrix of ap-cyclic successive overrelaxation (SOR) method for the solution of the linear systemAx = b, when the matrixA is blockp-cyclic consistently ordered, for what is known as the “one-point” problem, for anyp ⩾ 3. Particular cases of the “one-point” problem were solved by Young, Varga, Kjellberg, Kredell, Russell and others. In the present work we develop a theory using the results of our previous one and solve first the“two-point” problem special cases of which were solved by Wrigley, Eiermann, Niethammer, Ruttan, Noutsos and others. Secondly, we generalize and extend our theory to cover the“many-point” problem and develop a Young-Eidson's type algorithm for its solution. As possible application areas we mention among others the best blockp-cyclic repartitioning for the SOR method are the solution of large scale systems arising in queueing network problems in Markov analysis.

Published
1999
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46. Exact SOR convergence regions for a general class ofp-cyclic matrices

Author

Hadjidimos, A., Noutsos, D., and Tzoumas, M.

Abstract

Linear systems whose associated block Jacobi iteration matrixB is weakly cyclic generated by the cyclic permutation s = (s1,s2,..., sp) in the spirit of Li and Varga are considered. Regions of convergence for the corresponding blockp-cyclic SOR method are derived and the exact convergence domains for real spectra, s(Bp), of the same sign are obtained. Moreover, analytical expressions for two special cases forp = 5 are given and numerical results are presented confirming the theory developed. The tools used for this work are mainly from complex analysis and extensive use of (asteroidal) hypocycloids in the complex plane is made to produce our results.

Published
1995
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47. On the convergence of monoparametric k-step iterative euler methods for the solution of linear systems

Author

Galanis, S., Hadjidimos, A., and Noutsos, D.

Abstract

For the solution of the nonsingular linear system x = Tx+c, two monoparametric stationary k - step iterative methods are considered. By using Euler transforms and for various values of their parameter ω the two methods are analyzed and studied as regards: (i) Their (optimum) convergence for a given configuration of the spectrum σ(T) of T and (ii) Their region of convergence Rk, for a permissible ω, for all T's for which σ(T) ⊂ Rk. Answers to both questions are given and it is shown that if the two methods share the same quantity ρ, defined in the paper, the optimum second method is asymptotically much faster than the optimum first one.

Published
1988
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49. Optimum first and second order extrapolations of Successive Overrelaxation type methods for certain classes of matrices

Author

Galanis, S., Hadjidimos, A., and Noutsos, D.

Abstract

This paper deals with the iterative solution of the linear systemx=Bx+c when its Jacobi matrixB is weakly 2-cyclic consistently ordered and has a complex eigenvalue spectrum which lies on a straight-line segment. The optimization problem of the following three methods is considered and solved: i) The extrapolation of the optimum Successive Overrelaxation (SOR) ii) The second order extrapolation of a “good” SOR and iii) The second order extrapolation of the Gauss-Seidel method. In addition a variant of the second order methods considered, suitable for the solution of the system even ifB isnot necessarily weakly 2-cyclic consistently ordered, is proposed. Finally a reference to a theoretical comparison of the various optimum methods in the paper is made and their asymptotic convergence factors for selected eigenvalue spectra are illustrated in a Table in support of the theory developed.

Published
1989
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