Phase-resolved energy spectra of the Crab pulsar in the range of 50–400 GeV measured with the MAGIC telescopes

Aleksić, J.; Álvarez, Ezequiel; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, Michael; Barrio, J. A.; Bastieri, D.; González, J. Becerra; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Böck, R.; Boller, A.; Bonnoli, G.; Tridon, D. Borla; Braun, I.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Dazzi, F.; Angelis, A. De; Caneva, G. De; Pozo, E. De Cea del; Lotto, B. De; Mendez, C. Delgado; Ortega, A. Diago; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Eisenacher, D.; Elsäesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; López, R. J. García; Garczarczyk, M.; Garrido, Daniel; Giavitto, G.; Godinović, N.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, Dario; Jogler, T.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; Kushida, J.; Barbera, A. La; Lelas, D.; Leonardo, E.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Oramas, A.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martı́nez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Niedźwiecki, A.; Nieto, D.; Nilsson, K.; Nowak, N.; Orito, R.; Paneque, D.; Paoletti, R.; Pardo, Sharon; Paredes, J. M.; Partini, S.; Pérez-Torres, M. A.; Peršić, M.; Peruzzo, L.; Pilia, M.; Pochon, J.; Prada, Francisco; Moroni, P. G. Prada; Prandini, E.; Gimenez, I. Puerto; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Rügamer, S.; Saggion, A.; Saito, Koji; Saito, Takayuki; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shayduk, M.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Šnidarić, Iva; Sobczyńska, D.; Spanier, F.; Spiro, S.; Stamatescu, V.; Stamerra, A.; Steinke, B.; Storz, J.; Strah, N.; Surić, T.; Takalo, L. O.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Tibolla, O.; Torres, D. F.; Treves, A.; Uellenbeck, M.; Vankov, H.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zabalza, V.; Zandanel, F.; Zanin, R.; Hirotani, Kouichi

doi:10.1051/0004-6361/201118166

Cited by 96 publications

(105 citation statements)

References 22 publications

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“…It is commonly accepted that the observed HE gamma rays are primarily the result of curvature radiation from electrons/positrons accelerated along the magnetic field lines by the rotationally induced electric field, but the recent detections of pulsations from the Crab pulsar at energies up to ∼400 GeV by VERITAS (Aliu et al 2011) and MAGIC (Aleksić et al 2011(Aleksić et al , 2012 suggest that either an additional component is necessary or a different process is at work (e.g., Lyutikov 2012). The exact location in the magnetosphere where the acceleration occurs is still uncertain.…”

Section: Introductionmentioning

confidence: 99%

Constraints on the Emission Geometries and Spin Evolution of Gamma-Ray Millisecond Pulsars

Johnson

Venter

Harding

et al. 2014

ApJS

101

157

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Millisecond pulsars (MSPs) are a growing class of gamma-ray emitters. Pulsed gamma-ray signals have been detected from more than 40 MSPs with the Fermi Large Area Telescope (LAT). The wider radio beams and more compact magnetospheres of MSPs enable studies of emission geometries over a broader range of phase space than non-recycled radio-loud gamma-ray pulsars. We have modeled the gamma-ray light curves of 40 LAT-detected MSPs using geometric emission models assuming a vacuum retarded-dipole magnetic field. We modeled the radio profiles using a single-altitude hollow-cone beam, with a core component when indicated by polarimetry; however, for MSPs with gamma-ray and radio light curve peaks occurring at nearly the same rotational phase, we assume that the radio emission is co-located with the gamma rays and caustic in nature. The best-fit parameters and confidence intervals are determined using a maximum likelihood technique. We divide the light curves into three model classes, with gamma-ray peaks trailing (Class I), aligned (Class II), or leading (Class III) the radio peaks. Outer gap and slot gap (two-pole caustic) models best fit roughly equal numbers of Class I and II, while Class III are exclusively fit with pair-starved polar cap models. Distinguishing between the model classes based on typical derived parameters is difficult. We explore the evolution of the magnetic inclination angle with period and spin-down power, finding possible correlations. While the presence of significant off-peak emission can often be used as a discriminator between outer gap and slot gap models, a hybrid model may be needed.

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Section: Introductionmentioning

confidence: 99%

Constraints on the Emission Geometries and Spin Evolution of Gamma-Ray Millisecond Pulsars

Johnson

Venter

Harding

et al. 2014

ApJS

101

157

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“…However, the Fermi-LAT and the MAGIC data below 60 GeV can equally be well parameterized by a broken power law and an exponential cutoff. Recent observations by VERITAS and MAGIC revealed that in the higher energy range between 100 GeV and 400 GeV, the measured spectrum can be well described by only a simple power law with a spectral index equal to 3.8 (Aliu et al 2011;Aleksić et al 2012). Nevertheless, we assume that the detection of the exponential cutoff at higher (>400 GeV) photon energies is still quite realistic.…”

Section: Discussionmentioning

confidence: 86%

“…The VERITAS collaboration recently reported the detection of pulsed very high energy (VHE) γ -rays above 100 GeV from the Crab pulsar (Aliu et al 2011); this detection was later confirmed by observations from the MAGIC Cherenkov telescope (Aleksić et al 2011(Aleksić et al , 2012. Prior to that, the measured energy limit of pulsed emission was around 25 GeV (Aliu et al 2008).…”

Section: Introductionmentioning

confidence: 92%

ON THE SPECTRUM OF THE PULSED GAMMA-RAY EMISSION OF THE CRAB PULSAR FROM 10 MeV TO 400 GeV

Chkheidze

Machabeli

Osmanov

2013

ApJ

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In the present paper, a self-consistent theory, interpreting VERITAS and the MAGIC observations of the very high-energy pulsed emission from the Crab pulsar, is considered. The photon spectrum between 10 MeV and 400 GeV can be described by two power-law functions with spectral indices of 2.0 and 3.8. The source of the pulsed emission above 10 MeV is assumed to be synchrotron radiation, which is generated near the light cylinder during the quasi-linear stage of the cyclotron instability. The emitting particles are the primary beam electrons with Lorentz factors up to 10 9 . Such high energies of beam particles can be reached due to Landau damping of the Langmuir waves in the light cylinder region.

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“…The observations suffer then from non-optimal atmospheric conditions along their lineof-sight, instead of actively avoiding them. However, optimal atmospheric conditions may be decisive for the practicability of low-energy analyses [61], those requiring precision pointing [62], or those requiring maximum sensitivity for monitoring purposes, while other types of observations may be practically unaffected. Selecting data according to these criteria later on offline is hence the worst of all strategies, at least in terms of achievable duty cycle, and if sources with less sensitivity to such non-optimal conditions could have been observed instead.…”

Section: Intelligent Target Selectionmentioning

confidence: 99%

CTA Atmospheric Calibration

Gaug

2017

EPJ Web Conf.

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Abstract. The main contribution to the systematic uncertainties of Atmospheric Imaging Cherenkov Telescopes (IACTs) currently stems from the uncertainty in the determination of atmospheric properties for a given moment of observation. This technique uses the atmosphere as a calorimeter of gamma-ray induced atmospheric air showers and measures the amount of Cherenkov light collected by large mirrors and focused towards a pixellized camera. Atmospheric conditions affect the measured Cherenkov light yield in several ways: the air-shower development itself, the variation of the Cherenkov angle with altitude and the loss of photons due to scattering and absorption of Cherenkov light. Although IACTs use to be located at astronomical sites, characterized by extremely clear atmospheric conditions, the local atmosphere should be continuously monitored, in terms of molecular density profiles, aerosol extinction profiles, and clouds. Moreover, a general understanding of the site and particularly aerosol climatology is desirable for a robust interpretation of the sensing instruments' data. Here, the strategy of the Cherenkov Telescope Array (CTA) on atmospheric monitoring is presented, designed to ensure that the related systematic uncertainties are brought down by at least a factor of two with respect to current installations. Additionally, a more intelligent scheduling scheme is aimed at, where source observations are selected using dedicated auxiliary atmospheric monitoring instruments and taking into account the feasibility of a later analysis according to the underlying scientific case. This plan should reduce data loss during offline data selection and enhance the effective duty cycle of the CTA.

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Phase-resolved energy spectra of the Crab pulsar in the range of 50–400 GeV measured with the MAGIC telescopes

Cited by 96 publications

References 22 publications

Constraints on the Emission Geometries and Spin Evolution of Gamma-Ray Millisecond Pulsars

Constraints on the Emission Geometries and Spin Evolution of Gamma-Ray Millisecond Pulsars

ON THE SPECTRUM OF THE PULSED GAMMA-RAY EMISSION OF THE CRAB PULSAR FROM 10 MeV TO 400 GeV

CTA Atmospheric Calibration

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