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© ESO 2010. Supported by INFN Padova. We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Polish MNiSzW Grant No. N203 390834, by the YIP of the Helmholtz Gemeinschaft, and by grant DO02-353 of the the Bulgarian National Science Fund., Context. Part of the very high energy gamma-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the trajectories of these cascade pairs and, in turn, convert cosmic background photons to.-ray energies by inverse Compton scattering. These secondary photons can form an extended halo around bright VHE sources. Aims. We searched for an extended emission around the bright blazars Mrk 421 and Mrk 501 using the MAGIC telescope data. Methods. If extended emission is present, the angular distribution of reconstructed gamma-ray arrival directions around the source is broader than for a point-like source. In the analysis of a few tens of hours of observational data taken from Mrk 421 and Mrk 501 we used a newly developed method that provides better angular resolution. This method is based on the usage of multidimensional decision trees. Comparing the measured shapes of angular distributions with those expected from a point-like source one can detect or constrain possible extended emission around the source. We also studied the influence of different types of systematic errors on the shape of the distribution of reconstructed gamma-ray arrival directions for a point source. Results. We present upper limits for an extended emission calculated for both sources for various source extensions and emission profiles. We obtain upper limits on the extended emission around the Mrk 421 (Mrk 501) on the level of <5% (<4%) of the Crab Nebula flux above the energy threshold of 300 GeV. Using these results we discuss possible constraints on the extragalactic magnetic fields strength around a few times 10(-15) G., INFN Padova, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Polish MNiSzW, Helmholtz Gemeinschaft, Bulgarian National Science Fund, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Astronomical Society. Supported by INFN Padova.We thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN are gratefully acknowledged. This work was also supported by the Polish MNiSzW Grant N N203 390834, by the YIP of the Helmholtz Gemeinschaft, and by grant DO02-353 of the Bulgarian National Science Fund. S. T. is grateful for the support of the RATAN observations and the Russian Foundation for Basic Research, grant N08-02-00504-a., Cygnus X-3 is a microquasar consisting of an accreting compact object orbiting around a Wolf-Rayet star. It has been detected at radio frequencies and up to high-energy. rays (above 100 MeV). However, many models also predict a very high energy (VHE) emission (above hundreds of GeV) when the source displays relativistic persistent jets or transient ejections. Therefore, detecting such emission would improve the understanding of the jet physics. The imaging atmospheric Cherenkov telescope MAGIC observed Cygnus X-3 for about 70 hr between 2006 March and 2009 August in different X-ray/radio spectral states and also during a period of enhanced gamma-ray emission. MAGIC found no evidence for a VHE signal from the direction of the microquasar. An upper limit to the integral flux for energies higher than 250 GeV has been set to 2.2 x 10(-12) photons cm(-2) s(-1) (95% confidence level). This is the best limit so far to the VHE emission from this source. The non-detection of a VHE signal during the period of activity in the high-energy band sheds light on the location of the possible VHE radiation favoring the emission from the innermost region of the jets, where absorption is significant. The current and future generations of Cherenkov telescopes may detect a signal under precise spectral conditions., INFN Padova, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Polish MNiSzW, YIP of the Helmholtz Gemeinschaft, Bulgarian National Science Fund, RATAN observations, Russian Foundation for Basic Research, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 The Royal Astronomical Society. We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPANCSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the DFG Cluster of Excellence 'Origin and Structure of the Universe', by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3 and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0.The Fermi-LAT Collaboration acknowledges support from a number of agencies and institutes for both development and the operation of the LAT as well as scientific data analysis. These include NASA and DOE in the United States; CEA/Irfu and IN2P3/CNRS in France; ASI and INFN in Italy; MEXT, KEK and JAXA in Japan; and the K. A. Wallenberg Foundation, the Swedish Research Council and the National Space Board in Sweden. Additional support from INAF in Italy and CNES in France for science analysis during the operations phase is also gratefully acknowledged. This research is partially supported by NASA through the Fermi Guest Investigator Grants NNX09AT92G and NNX10AP22G. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester., Indications of a GeV component in the emission from gamma-ray bursts (GRBs) are known since the Energetic Gamma-Ray Experiment Telescope observations during the 1990s and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy (VHE) photons (E > 30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z = 1.547) field and Fermi Large Area Telescope data in the same time interval are analysed to derive upper limits of the GeV/TeV emission. We compare these results to the expected emissions evaluated for different processes in the framework of a relativistic blastwave model for the afterglow. Simultaneous upper limits with Fermi and a Cherenkov telescope have been derived for this GRB observation. The results we obtained are compatible with the expected emission although the difficulties in predicting the HE and VHE emission for the afterglow of this event makes it difficult to draw firmer conclusions. Nonetheless, MAGIC sensitivity in the energy range of overlap with space-based instruments (above about 40 GeV) is about one order of magnitude better with respect to Fermi. This makes evident the constraining power of ground-based observations and shows that the MAGIC telescope has reached the required performance to make possible GRB multiwavelength studies in the VHE range., German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Spanish Consolider-Ingenio programme, Bulgarian NSF, Academy of Finland, DFG Cluster of Excellence 'Origin and Structure of the Universe', DFG Collaborative Research Centers, Polish MNiSzW, NASA through the Fermi Guest Investigator, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© Elsevier. The authors wish to thank the financial support given by the CICYT (project FPA2003-9543-C02-01) which made this work possible, and the IAC for providing excellent working conditions in La Palma. The MAGIC telescope is mainly supported by BMBF (Germany), CICYT (Spain), INFN and MUR (Italy). We also acknowledge Razmik Mirzoyan, Manel Martinez, Eva Domingo and the IFAE engineering team, Alex Gonzalez and Isaac Martinez for their valuable help in the installation. Also, we thank Juan Cortina and Emma On˜ a-Wilhelmi of the IFAE group for their suggestions and help in modifying the PMT base., The MAGIC telescope has been designed for the observation of Cherenkov light generated in Extensive Air Showers initiated by cosmic particles. However, its 17m diameter mirror and optical design makes the telescope suitable for direct optical observations as well. In this paper, we report about the development of a system based on the use of a dedicated photo-multiplier (PMT) for optical observations. This PMT is installed in the centre of the MAGIC camera (the so-called central pixel). An electro-to-optical system has been developed in order to transmit the PMT output signal by an optical fibre to the counting room, where it is digitized and stored for off-line analysis. The performance of the system using the optical pulsation of the Crab nebula as calibration source is presented. The time required for a 5 sigma detection of the Crab pulsar in the optical band is less than 20s. The central pixel will be mainly used to perform simultaneous observations of the Crab pulsar both in the optical and gamma-ray regimes. It will also allow for periodic testing of the precision of the MAGIC timing system using the Crab rotational optical pulses as a very precise timing reference. (c) 2008 Elsevier B.V. All rights reserved., CICYT, German BMBF, INFN, MUR, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO, 2012. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Marie Curie program, by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the YIP of the Helmholtz Gemeinschaft, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESSMAGIC /2010/0. We thank R. Bühler, L. Costamante and B. Giebels for providing H.E.S.S. and multi-wavelength data. We also thank the anonymous referee for useful comments which helped to improve the manuscript., Context. The high frequency peaked BL Lac PKS 2155-304 with a redshift of z = 0.116 was discovered in 1997 in the very high energy (VHE, E > 100 GeV) gamma-ray range by the University of Durham Mark VI gamma-ray Cherenkov telescope in Australia with a flux corresponding to 20% of the Crab Nebula flux. It was later observed and detected with high significance by the southern Cherenkov observatory H. E. S. S. establishing this source as the best studied southern TeV blazar. Detection from the northern hemisphere is difficult due to challenging observation conditions under large zenith angles. In July 2006, the H. E. S. S. collaboration reported an extraordinary outburst of VHE gamma-emission. During the outburst, the VHE gamma-ray emission was found to be variable on the time scales of minutes and with a mean flux of similar to 7 times the flux observed from the Crab Nebula. Follow-up observations with the MAGIC-I standalone Cherenkov telescope were triggered by this extraordinary outburst and PKS 2155-304 was observed between 28 July to 2 August 2006 for 15 h at large zenith angles. Aims. We studied the behavior of the source after its extraordinary flare. Furthermore, we developed an analysis method in order to analyze these data taken under large zenith angles. Methods. Here we present an enhanced analysis method for data taken at high zenith angles. We developed improved methods for event selection that led to a better background suppression. Results. The quality of the results presented here is superior to the results presented previously for this data set: detection of the source on a higher significance level and a lower analysis threshold. The averaged energy spectrum we derived has a spectral index of (-3.5 +/- 0.2) above 400 GeV, which is in good agreement with the spectral shape measured by H. E. S. S. during the major flare on MJD 53 944. Furthermore, we present the spectral energy distribution modeling of PKS 2155-304. With our observations we increased t, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Marie Curie program, Spanish Consolider-Ingenio 2010 programme, Bulgarian NSF, Academy of Finland, YIP of the Helmholtz Gemeinschaft, DFG Cluster of Excellence “Origin and Structure of the Universe”, DFG Collaborative Research Centers, Polish MNiSzW, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2015 Elsevier B.V. Artículo firmado por 167 autores. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO, and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Centro de Excelencia Severo Ochoa SEV-2012-0234, CPAN CSD2007-00042, and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant 268740 of the Academy of Finland, by the Croatian Science Foundation (HrZZ) Project 09/176 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0. We thank the two anonymous referees for thorough reading and helpful comments on the manuscript., The MAGIC telescopes are two Imaging Atmospheric Cherenkov Telescopes (IACTs) located on the Canary island of La Palma. The telescopes are designed to measure Cherenkov light from air showers initiated by gamma rays in the energy regime from around 50 GeV to more than 50 TeV. The two telescopes were built in 2004 and 2009, respectively, with different cameras, triggers and readout systems. In the years 2011-2012 the MAGIC collaboration undertook a major upgrade to make the stereoscopic system uniform, improving its overall performance and easing its maintenance. In particular, the camera, the receivers and the trigger of the first telescope were replaced and the readout of the two telescopes was upgraded. This paper (Part I) describes the details of the upgrade as well as the basic performance parameters of MAGIC such as raw data treatment, linearity in the electronic chain and sources of noise. In Part II, we describe the physics performance of the upgraded system., German BMBF and MPG, Italian INFN and INAF, Swiss National Fund SNF, ERDF under the Spanish MINECO, Japanese JSPS, MEXT, Centro de Excelencia Severo Ochoa, Spanish Consolider-Ingenio 2010 programme, Academy of Finland, Croatian Science Foundation (HrZZ), University of Rijeka, the DFG Collaborative Research Centers, Polish MNiSzW, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Astronomical Society. We acknowledge the use of public data from the Swift and RXTE data archives. The Metsahovi team acknowledges the support from the Academy of Finland for the observing projects (numbers 212656, 210338, among others). This research has made use of data obtained from the National Radio Astronomy Observatory's Very Long Baseline Array (VLBA), projects BK150, BP143, and BL149 (MOJAVE). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The St. Petersburg University team acknowledges support from the Russian RFBR foundation via grant 09-02-00092. AZT-24 observations are made within an agreement between Pulkovo, Rome and Teramo observatories. This research is partly based on observations with the 100 m telescope of the MPIfR (Max-Planck-Institut fur Radioastronomie) at Effelsberg, as well as with the Medicina and Noto telescopes operated by INAF-Istituto di Radioastronomia. RATAN-600 observations were supported in part by the RFBR grant 08-02-00545 and the OVRO 40 m program was funded in part by NASA (NNX08AW31G) and the NSF (AST-0808050). The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. M. Villata organized the optical-to-radio observations by GASP-WEBT as the president of the collaboration. The Abastumani Observatory team acknowledges financial support by the Georgian National Science Foundation through grant GNSF/ST07/4-180., We report on the gamma-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) gamma-ray spectrum above 0.3 GeV can be well described by a power-law function with photon index Gamma = 1.78 +/- 0.02 and average photon flux F(>0.3 GeV) = (7.23 +/- 0.16) x 10(-8) ph cm(-2) s(-1). Over this time period, the Fermi-LAT spectrum above 0.3 GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor similar to 3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in gamma-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk 421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk 421 showed a low activity at all wavebands. The extensive multi-instrument (radio to TeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site., Academy of Finland, Russian RFBR foundation, RFBR, NASA, NSF, Smithsonian Institution, Academia Sinica, Georgian National Science Foundation, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Astronomical Society. We would like to thank the IAC for the excellent working conditions on the La Palma Observatory Roque de los Muchachos. We are grateful to the RXTE ASMteamfor their quick-look results. The support of the German BMBF andMPG, the Italian INFN, and the Spanish CICYT is gratefully acknowledged. This work was also supported by ETH research grant TH-34/04-3 and by Polish grant MNiI 1P03D01028. In addition, the authors want to thank Deirdre Horan, Martin Tluczykont, and Frédéric Piron for providing Mrk 501 data from WHIPPLE, HEGRA CT1, and HEGRA CT System and CAT, respectively, and for useful discussions., We report on very high energy gamma-ray observations with the MAGIC Telescope of the pulsar PSR B1951+32 and its associated nebula, CTB 80. Our data constrain the cutoff energy of the pulsar to be less than 32 GeV, assuming the pulsed gamma-ray emission to be exponentially cut off. In the case that the cutoff follows a superexponential behavior, the cutoff energy can be as high as similar to 60 GeV. The upper limit on the flux of pulsed gamma-ray emission above 75 GeV is 4.3; 10(-11) photons cm(-2) s(-1), and the upper limit on the flux of steady emission above 140 GeV is 1.5; 10(-11) photons cm(-2) s(-1). We discuss our results in the framework of recent model predictions and other studies., German BMBF, German MPG, Italian INFN, Spanish CICYT, ETH, Polish grant MNiI, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2014. We are grateful to the journal referee, who helped us to improve the quality of this manuscript. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by Projekt 09/176 of the Croatian science Foundation, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzWgrant 745/N-HESS-MAGIC/2010/0. This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation and the Smithsonian Institution, by NSERC in Canada, by Science Foundation Ireland (SFI 10/RFP/AST2748) and by STFC in the U.K. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the instrument. The St. Petersburg University team acknowledges support from Russian RFBR foundation, grant 12-02-00452. The Abastumani Observatory team acknowledges financial support by the Georgian National Science Foundation through grant GNSF/ST07/180. The Metsähovi team acknowledges the support from the Academy of Finland to our observing projects (numbers 212656, 210338, 121148, and others). We acknowledge the use of public data fromthe Swift and RXTE data archive., Context: Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (> 100 GeV, hereafter VHE).Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. However, most of the -ray studies performed on Mrk 501 during the past years relate to flaring activity, when the source detection and characterization with the available -ray instrumentation was easier to perform. Aims: Our goal is to characterize in detail the source -ray emission, together with the radio-to-X-ray emission, during the non-flaring (low) activity, which is less often studied than the occasional flaring (high) activity. Methods:We organized a multiwavelength (MW) campaign on Mrk 501 between March and May 2008. This multi-instrument effort included the most sensitive VHE -ray instruments in the northern hemisphere, namely the imaging atmospheric Cherenkov telescopes MAGIC and VERITAS, as well as Swift, RXTE, the F-GAMMA, GASP-WEBT, and other collaborations and instruments. This provided extensive energy and temporal coverage of Mrk 501 throughout the entire campaign. Results: Mrk 501 was found to be in a low state of activity during the campaign, with a VHE flux in the range of 10%–20% of the Crab nebula flux. Nevertheless, significant flux variations were detected with various instruments, with a trend of increasing variability with energy and a tentative correlation between the X-ray and VHE fluxes. The broadband spectral energy distribution during the two different emission states of the campaign can be adequately described within the homogeneous one-zone synchrotron self-Compton model, with the (slightly) higher state described by an increase in the electron number density. Conclusions: The one-zone SSC model can adequately describe the broadband spectral energy distribution of the source during the two months covered by the MW campaign. This agrees with previous studies, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2012. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESSMAGIC/2010/0., Context. We present the results of a long M 87 monitoring campaign in very high energy.-rays with the MAGIC-I Cherenkov telescope. Aims. We aim to model the persistent non-thermal jet emission by monitoring and characterizing the very high energy gamma-ray emission of M 87 during a low state. Methods. A total of 150 h of data were taken between 2005 and 2007 with the single MAGIC-I telescope, out of which 128.6 h survived the data quality selection. We also collected data in the X-ray and Fermi-LAT bands from the literature (partially contemporaneous). Results. No flaring activity was found during the campaign. The source was found to be in a persistent low-emission state, which was at a confidence level of 7 sigma. We present the spectrum between 100 GeV and 2 TeV, which is consistent with a simple power law with a photon index Gamma = 2.21 +/- 0.21 and a flux normalization at 300GeV of (7.7 +/- 1.3) x 10(-8) TeV-1 s(-1) m(-2). The extrapolation of the MAGIC spectrum into the GeV energy range matches the previously published Fermi-LAT spectrum well, covering a combined energy range of four orders of magnitude with the same spectral index. We model the broad band energy spectrum with a spine layer model, which can satisfactorily describe our data., German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Spanish Consolider-Ingenio 2010 programme, Bulgarian NSF, Academy of Finland, DFG Cluster of Excellence “Origin and Structure of the Universe”, DFG Collaborative Research Centers, Polish MNiSzW, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Marie Curie program, by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 program, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the YIP of the Helmholtz Gemeinschaft, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0. C.P. gratefully acknowledges financial support of the Klaus Tschira Foundation, We report on the detection of very-high energy (VHE, E > 100 GeV) gamma-ray emission from NGC 1275, the central radio galaxy of the Perseus cluster of galaxies. The source has been detected by the MAGIC telescopes with a statistical significance of 6.6s above 100 GeV in 46 h of stereo observations carried out between August 2010 and February 2011. The measured differential energy spectrum between 70 GeV and 500 GeV can be described by a power law with a steep spectral index of Gamma = -4.1 +/- 0.7(stat) +/- 0.3(syst), and the average flux above 100 GeV is F-gamma = (1.3 +/- 0.2(stat) +/- 0.3(syst)) x 10(-11) cm(-2) s(-1). These results, combined with the power-law spectrum measured in the first two years of observations by the Fermi-LAT above 100 MeV, with a spectral index of Gamma similar or equal to -2.1, strongly suggest the presence of a break or cut-off around tens of GeV in the NGC 1275 spectrum. The light curve of the source above 100 GeV does not show hints of variability on a month time scale. Finally, we report on the nondetection in the present data of the radio galaxy IC 310, previously discovered by the Fermi-LAT and MAGIC. The derived flux upper limit F-gamma(U.L.) (> 300 GeV) = 1.2 x 10(-12) cm(-2) s(-1) is a factor similar to 3 lower than the mean flux measured by MAGIC between October 2009 and February 2010, thus confirming the year time-scale variability of the source at VHE., German MPG, German BMBF, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Marie Curie program, Spanish Consolider-Ingenio program, Bulgarian NSF, Academy of Finland, YIP of the Helmholtz Gemeinschaft, DFG Cluster of Excellence "Origin and Structure of the Universe", DFG Collaborative Research Centers, Polish MNiSzW, Klaus Tschira Foundation, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© Wiley. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant 127740 of the Academy of Finland, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzWgrant 745/N-HESSMAGIC/2010/0., The bright gamma-ray quasar 4C +55.17 is a distant source (z = 0.896) with a hard spectrum at GeV energies as observed by the Large Area Telescope (LAT) on board the Fermi satellite. This source is identified as a good source candidate for very high energy (VHE; > 30 GeV) gamma-rays. In general, VHE gamma-rays from distant sources provide a unique opportunity to study the extragalactic background light (EBL) and underlying astrophysics. The flux intensity of this source in the VHE range is investigated. Then, constraints on the EBL are derived from the attenuation of gamma-ray photons coming from the distant blazar. We searched for a gamma-ray signal from this object using the 35 h observations taken by the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes between 2010 November and 2011 January. No significant VHE gamma-ray signal was detected. We computed the upper limits of the integrated gamma-ray flux at the 95 per cent confidence level of 9.4 x 10(-12) and 2.5 x 10(-12) cm(-2) s(-1) above 100 and 200 GeV, respectively. The differential upper limits in four energy bins in the range from 80 to 500 GeV are also derived. The upper limits are consistent with the attenuation predicted by low-flux EBL models on the assumption of a simple power-law spectrum extrapolated from LAT data., German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Spanish Consolider-Ingenio 2010 progr, Academy of Finland, DFG Cluster of Excellence “Origin and Structure of the Universe”, DFG Collaborative Research Center, Polish MNiSzWgrant, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2015. The American Astronomical Society. Artículo firmado por 278 autores. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). The MAGIC Collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO, and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Centro de Excelencia Severo Ochoa SEV- 2012-0234, CPAN CSD2007-00042, and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant 268740 of the Academy of Finland, by the Croatian Science Foundation (HrZZ) Project 09/176 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0. This research is also supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, and the Smithsonian Institution, by NSERC in Canada, by Science Foundation Ireland (SFI 10/ RFP/AST2748), and by STFC in the U.K. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the VERITAS instrument. The VERITAS Coll, We report on simultaneous broadband observations of the TeV-emitting blazar Markarian 501 between 2013 April 1 and August 10, including the first detailed characterization of the synchrotron peak with Swift and NuSTAR. During the campaign, the nearby BL Lac object was observed in both a quiescent and an elevated state. The broadband campaign includes observations with NuSTAR, MAGIC, VERITAS, the Fermi Large Area Telescope, Swift X-ray Telescope and UV Optical Telescope, various ground-based optical instruments, including the GASPWEBT program, as well as radio observations by OVRO, Metsähovi, and the F-Gamma consortium. Some of the MAGIC observations were affected by a sand layer from the Saharan desert, and had to be corrected using eventby-event corrections derived with a Light Detection and Ranging (LIDAR) facility. This is the first time that LIDAR information is used to produce a physics result with Cherenkov Telescope data taken during adverse atmospheric conditions, and hence sets a precedent for the current and future ground-based gamma-ray instruments. The NuSTAR instrument provides unprecedented sensitivity in hard X-rays, showing the source to display a spectral energy distribution (SED) between 3 and 79 keV consistent with a log-parabolic spectrum and hard X-ray variability on hour timescales. None (of the four extended NuSTAR observations) show evidence of the onset of inverse-Compton emission at hard X-ray energies. We apply a single-zone equilibrium synchrotron selfCompton (SSC) model to five simultaneous broadband SEDs. We find that the SSC model can reproduce the observed broadband states through a decrease in the magnetic field strength coinciding with an increase in the luminosity and hardness of the relativistic leptons responsible for the high-energy emission., Ministerio de Economía y Competitividad (MINECO), España, NASA, German BMBF and MPG, Italian INFN and INAF, Swiss National Fund SNF, Japanese JSPS and MEXT, Centro de Excelencia Severo Ochoa, Spanish Consolider-Ingenio 2010 programme, Academy of Finland, Croatian Science Foundation (HrZZ), University of Rijeka, DFG Collaborative Research Centers, Polish MNiSzW, U.S. Department of Energy Office of Science, U.S. National Science Foundation, Smithsonian Institution, NSERC in Canada, Science Foundation Ireland, STFC in the U.K, National Aeronautics and Space Administration and the Department of Energy in the United States, Commissariat à l’Energie Atomique in France, Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, Agenzia Spaziale Italiana, Istituto Nazionale di Fisica Nucleare in Italy, Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan, High Energy Accelerator Research Organization (KEK) in Japan, Japan Aerospace Exploration Agency (JAXA), K. A. Wallenberg Foundation the Swedish Research Council, Swedish National Space Board in Sweden, Istituto Nazionale di Astrofisica in Italy, Centre National d’Études Spatiales in France, INSU/CNRS (France), IGN (Spain), Istanbul University, Bilim Akademisi, TUBITAK, Russian RFBR, St. Petersburg University, NASA Fermi Guest Investigator, Swift Guest Investigator, Scientific Research Fund of the Bulgarian Ministry of Education and Sciences, Shota Rustaveli National Science Foundation, Institute of Astronomy and Rozhen National Astronomical Observatory, Bulgarian Academy of Sciences, Ministry of Education, Science and Technological Development of the Republic of Serbia, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Astronomical Society. Supported by INFN Padova.We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Polish MNiSzW Grant N N203 390834, by the YIP of the Helmholtz Gemeinschaft, and by grant DO02-353 of the Bulgarian National Science Fund., Between 2004 and 2009, a sample of 28 X-ray selected high-and intermediate-frequency peaked blazars with an X-ray flux larger than 2 mu Jy at 1 keV in the redshift range from 0.018 to 0.361 was observed with the MAGIC telescope at energies above 100 GeV. Seven among them were detected and the results of these observations are discussed elsewhere. Here we concentrate on the remaining 21 blazars which were not detected during this observation campaign and present the 3 sigma (99.7%) confidence upper limits on their flux. The individual flux upper limits lie between 1.6% and 13.6% of the integral flux from the Crab Nebula. Applying a stacking method to the sample of non-detections with a total of 394.1 hr exposure time, we find evidence for an excess with a cumulative significance of 4.9 standard deviations. It is not dominated by individual objects or flares, but increases linearly with the observation time as for a constant source with an integral flux level of similar to 1.5% of that observed from the Crab Nebula above 150 GeV., INFN Padova, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Polish MNiSzW, YIP of the Helmholtz Gemeinschaft, Bulgarian National Science Fund, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© Science. This work was also supported by ETH research grant TH 34/043, the Polish MniSzW grant N N203 390834, and the Young Investigators Program of the Helmholtz Gemeinschaft. VERITAS: This research is supported by grants from the U.S. Department of Energy, NSF, the Smithsonian Institution, the Natural Sciences and Engineering Research Council of Canada, Science Foundation Ireland, and the STFC in the U.K. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and the collaborating institutions in the construction and operation of the instrument. VLBA: The Very Long Baseline Array is operated by the National Radio Astronomy Observatory, a facility of NSF, operated under cooperative agreement by Associated Universities, Inc., The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole., ETH, Polish MniSzW, Young Investigators Program of the Helmholtz Gemeinschaft, U.S. Department of Energy, NSF, Smithsonian Institution, Natural Sciences and Engineering Research Council of Canada, Science Foundation Ireland, STFC, U.K, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2012. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESSMAGIC/2010/0., Context. Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field. Aims. We study for the first time the possible very high energy gamma-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+ 61 and 1E 2259+586. Methods. We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U0142+61 was observed with the MAGIC I telescope in 2008 for about 25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for about 14 h. The data were analyzed with the standard MAGIC analysis software. Results. Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52 x 10(-12) cm(-2) s(-1) and 2.7 x 10(-12) cm(-2) s(-1) with a confidence level of 95% for 4U 0142+ 61 and 1E 2259+586, respectively. The resulting differential upper limits are presented together with X-ray data and upper limits in the GeV energy range., German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Spanish Consolider-Ingenio 2010 programme, Bulgarian NSF, Academy of Finland, DFG Cluster of Excellence “Origin and Structure of the Universe”, DFG Collaborative Research Centers, Polish MNiSzW, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2010. We thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN and Spanish MICINN is gratefully acknowledged. This work was also supported by ETH Research Grant TH 34/043, by the Polish MNiSzW Grant N N203 390834, and by the YIP of the Helmholtz Gemeinschaft., Context. Wide-range spectral coverage of blazar-type active galactic nuclei is of paramount importance for understanding the particle acceleration mechanisms assumed to take place in their jets. The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multiwavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of April 28 and 29, 2006, and June 14, 2006. Aims. We analyzed the corresponding MAGIC very-high energy observations during 9 nights from April 22 to 30, 2006 and on June 14, 2006. We inferred light curves with sub-day resolution and night-by-night energy spectra. Methods. MAGIC detects gamma-rays by observing extended air showers in the atmosphere. The obtained air-shower images were analyzed using the standard MAGIC analysis chain. Results. A strong gamma-ray signal was detected from Mkn 421 on all observation nights. The flux (E > 250 GeV) varied on night-by-night basis between (0.92 +/- 0.11) x 10(-10) cm(-2) s(-1) (0.57 Crab units) and (3.21 +/- 0.15) x 10(-10) cm(-2) s(-1) (2.0 Crab units) in April 2006. There is a clear indication for intra-night variability with a doubling time of 36 +/- 10(stat) min on the night of April 29, 2006, establishing once more rapid flux variability for this object. For all individual nights gamma-ray spectra could be inferred, with power-law indices ranging from 1.66 to 2.47. We did not find statistically significant correlations between the spectral index and the flux state for individual nights. During the June 2006 campaign, a flux substantially lower than the one measured by the Whipple 10-m telescope four days later was found. Using a log-parabolic power law fit we deduced for some data sets the location of the spectral peak in the very-high energy regime. Our results confirm the indications of rising peak energy with increasing flux, as expected in leptonic acceleration models., German BMBF, German MPG, Italian INFN, Spanish MICINN, ETH, Polish MNiSzW, YIP of the Helmholtz Gemeinschaft, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© The American Astronomical Society. The H.E.S.S. Collaboration acknowledges support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S., as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the French Ministry for Research, the CNRS-IN2P3 and the Astroparticle Interdisciplinary Programme of the CNRS, the U.K. Science and Technology Facilities Council (STFC), the IPNP of the Charles University, the Polish Ministry of Science and Higher Education, the South African Department of Science and Technology and National Research Foundation, and by the University of Namibia. We appreciate the excellent work of the technical support staff in Berlin, Durham, Hamburg, Heidelberg, Palaiseau, Paris, Saclay, and in Namibia in the construction and operation of the equipment.The MAGIC Collaboration thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the Marie Curie program, by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant DO02-353 of the Bulgarian NSF, by grant 127740 of the Academy of Finland, by the YIP of the Helmholtz Gemeinschaft, by the DFG Cluster of Excellence "Origin and Structure of the Universe," by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0.The VERITAS Collaboration acknowledges support from the US Department of Energy Office of Science, the US National Science Foundation, and the Smithsonian Institution, from NSERC in Canada, from Science Foundation Ireland (SFI 10/RFP/AST2748), and from STFC in the UK. We acknowledge the excellent work of the technical, The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of tau(rise)(d) = (1.69 +/- 0.30) days and tau(decay)(d) = (0.611 +/- 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (similar to day), peak fluxes (Phi(>0.35 TeV) similar or equal to (1-3) x 10(-11) photons cm(-2) s(-1)), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken similar to 3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core (flux increased by factor similar to 2; variability timescale <2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubb, Facilities Council (STFC), IPNP of the Charles University, Polish Ministry of Science and Higher Education, South African Department of Science and Technology, National Research Foundation, University of Namibia, German BMBF, German MPG, Italian INFN, Swiss National Fund SNF, Spanish MICINN, Bulgarian NSF, Academy of Finland, YIP of the Helmholtz Gemeinschaft, DFG Cluster of Excellence "Origin and Structure of the Universe", DFG Collaborative Research Centers, Polish MNiSzW, US Department of Energy Office of Science, US National Science Foundation, Smithsonian Institution, NSERC in Canada, Science Foundation Ireland (SFI), STFC in the UK, Istituto Nazionale di Astrofisica in Italy, Centre National d'Etudes Spatiales in France, NASA, Associated Universities, Inc., European Community, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Artículo firmado por 193 autores. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF, MPG and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovación (MICINN) (PID2019-104114RBC31, PID2019-104114RB-C32, PID2019-104114RB-C33, PID2019105510GB-C31, PID2019-107847RB-C41, PID2019-107847RB-C42, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-400/18.12.2020 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia ``Severo Ochoa'' (SEV-2016-0588, CEX2019-000920-S), the Unidad de Excelencia ``María de Maeztu'' (CEX2019-000918-M, MDM-20150509-18-2) and by the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP2016-06-9782 and the University of Rijeka Project 13.12.1.3.02; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; the Polish National Research Centre grant UMO2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq and FAPERJ. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 754510., Milky Way dwarf spheroidal galaxies (dSphs) are among the best candidates to search for signals of dark matter annihilation with Imaging Atmospheric Cherenkov Telescopes, given their high mass-to-light ratios and the fact that they are free of astrophysical gamma-ray emitting sources. Since 2011, MAGIC has performed a multi-year observation program in search for Weakly Interacting Massive Particles (WIMPs) in dSphs. Results on the observations of Segue 1 and Ursa Major II dSphs have already been published and include some of the most stringent upper limits (ULs) on the velocity-averaged cross-section of WIMP annihilation from observations of dSphs. In this work, we report on the analyses of 52.1 h of data of Draco dSph and 49.5 h of Coma Berenices dSph observed with the MAGIC telescopes in 2018 and in 2019 respectively. No hint of a signal has been detected from either of these targets and new constraints on the of WIMP candidates have been derived. In order to improve the sensitivity of the search and reduce the effect of the systematic uncertainties due to the J-factor estimates, we have combined the data of all dSphs observed with the MAGIC telescopes. Using 354.3 h of dSphs good quality data, 95% CL ULs on have been obtained for 9 annihilation channels. For most of the channels, these results reach values of the order of 10(-24) cm(3)/s at( )similar to TeV and are the most stringent limits obtained with the MAGIC telescopes so far. (C) 2021 Elsevier B.V. All rights reserved., Union Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICINN)/FEDER, Centro de Excelencia Severo Ochoa, Unidad de Excelencia María de Maeztu, German BMBF Federal Ministry of Education & Research (BMBF), MPG Max Planck Society, HGF, Italian INFN Istituto Nazionale di Fisica Nucleare (INFN), INAF Istituto Nazionale Astrofisica (INAF), Swiss National Fund SNF Swiss National Science Foundation (SNSF), Indian Department of Atomic Energy, Japanese ICRR, University of Tokyo, JSPS Ministry of Education, Culture, Sports, Science and Technology, Japan, MEXT Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), Bulgarian Ministry of Education and Science, National RI Roadmap Project, Academy of Finland Academy of Finland, CERCA program of the Generalitat de Catalunya, Croatian Science Foundation (HrZZ) Project, University of Rijeka, DFG Collaborative Research Center, Polish National Research Centre, Brazilian MCTIC, CNPq Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ), FAPERJ Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Artículo firmado por 443 autores. MAGIC acknowledgements: MAGIC would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF, MPG, and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the grants PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-104114RB-C33, PID2019-105510GB-C31, PID2019-107847RB-C41, PID2019-107847RB-C42, PID2019-107847RB-C44, PID2019-107988GB-C22 funded by MCIN/AEI/ 10.13039/501100011033; the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-400/18.12.2020 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also been supported by Centros de Excelencia 'Severo Ochoa' y Unidades 'Maria de Maeztu' program of the MCIN/AEI/ 10.13039/501100011033 (SEV-2016-0588, SEV-2017-0709, CEX2019-000920-S, CEX2019-000918-M, MDM-2015-0509-18-2) and by the CERCA institution of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project uniri-prirod-18-48; by the DFG Collaborative Research Centers SFB1491 and SFB876/C3; the Polish Ministry Of Education and Science grant No. 2021/WK/08; and by the Brazilian MCTIC, CNPq and FAPERJ. H.E.S.S. acknowledgements: the support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat a l'energie atomiqu, MAXIJ1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to similar to 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 10(11) and 10(13) cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA., German BMBF, German MPG, German HGF, Italian INFN, Italian INAF, Swiss National Fund SNF, MCIN/AEI, Indian Department of Atomic Energy, Japanese ICRR, University of Tokyo, JSPS, MEXT, Bulgarian Ministry of Education and Science, National RI Roadmap Project, Academy of Finland, Centros de Excelencia 'Severo Ochoa' y Unidades 'María de Maeztu' program of the MCIN/AEI, CERCA institution of the Generalitat de Catalunya, Croatian Science Foundation (HrZZ), University of Rijeka, DFG, Polish Ministry Of Education and Science, MCTIC, CNPq, FAPERJ, German Ministry for Education and Research (BMBF), Max Planck Society, German Research Foundation (DFG), Helmholtz Association, Alexander von Humboldt Foundation, French Ministry of Higher Education, Research and Innovation, Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), Commissariat a l'energie atomique et aux energies alternatives (CEA), U.K. Science and Technology Facilities Council (STFC), Irish Research Council (IRC), Science Foundation Ireland (SFI), Knut and Alice Wallenberg Foundation, South African Department of Science and Technology, National Research Foundation, University of Namibia, National Commission on Research, Science & Technology of Namibia (NCRST), Austrian Federal Ministry of Education, Science and Research, Austrian Science Fund (FWF), Australian Research Council (ARC), Japan Society for the Promotion of Science, University of Amsterdam, Science Committee of Armenia, EGI Federation, U.S. Department of Energy Office of Science, U.S. National Science Foundation, Smithsonian Institution, NSERC in Canada, National Energy Research Scientific Computing Center (NERSC), U.S. Department of Energy Office of Science User Facility, MCIN, Agencia Estatal de Investigación, Unidad de Excelencia María de Maeztu 2020-2023, European Research Council (ERC) under the European Union, Ministerio de Asuntos Económicos y Transformación Digital, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. Artículo firmado por 223 autores. The MAGIC collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de losMuchachos in La Palma. The financial support of the German BMBF and MPG; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish MINECO (FPA2017-87859-P, FPA2017-85668-P, FPA201782729-C6-2-R, FPA2017-82729-C6-6-R, FPA2017-82729-C6-5-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2017-87055-C22-P, FPA2017-90566-REDC); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia 'Severo Ochoa' SEV-2016-0588 and SEV-2015-0548, the Unidad de Excelencia 'Maria de Maeztu' MDM-2014-0369 and the 'la Caixa' Foundation (fellowshipLCF/BQ/PI18/11630012), by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, theCommissariat `a l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucl ' eaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fis, We report a characterization of the multiband flux variability and correlations of the nearby (z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsahovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F->1 TeV < 1.7 x 10(-12) ph cm(-2) s(-1)) and in the 2-10 keV (X-ray) band (F2-10 keV < 3.6 x 10(-11) erg cm(-2) s(-1)), during which the Swift-BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy (E > 0.1 TeV) gamma-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of 43(-6)(+9) d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process., Ministerio de Economía y Competitividad (MINECO)/FEDER, Centro de Excelencia Severo Ochoa, Unidad de Excelencia María de Maeztu, German BMBF Federal Ministry of Education & Research (BMBF), MPG Max Planck Society, Italian INFN Istituto Nazionale di Fisica Nucleare (INFN), INAF Istituto Nazionale Astrofisica (INAF), Swiss National Fund SNF Swiss National Science Foundation (SNSF), Indian Department of Atomic Energy, Japanese ICRR, University of Tokyo, JSPS Ministry of Education, Culture, Sports, Science and Technology, Japan, MEXT Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), Bulgarian Ministry of Education and Science, National RI Roadmap Project, Academy of Finland European Commission, Foundation La Caixa, Croatian Science Foundation, University of Rijeka Project, DFG German Research Foundation European Commission, Polish National Research Centre, Brazilian MCTIC, CNPq Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, FAPERJ Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro, DOE United States Department of Energy, NASA Fermi Guest Investigator grant, ETH Zurich, Swiss SNF Swiss National Science Foundation, German BMBF (Verbundforschung Astro-und Astroteilchenphysik) Federal Ministry of Education & Research, HAP (Helmholtz Alliance for Astroparticle Physics), Deutsche Forschungsgemeinschaft (DFG ) German Research Foundation, NASA National Aeronautics & Space Administration, NSF National Science Foundation, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2020. The American Astronomical Society. All rights reserved. Artículo firmado por 259 autores. This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, the Smithsonian Institution, and NSERC in Canada. This research used resources provided by the Open Science Grid, which is supported by the National Science Foundation and the U.S. Department of Energy's Office of Science, and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under contract No. DE-AC0205CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and the collaborating institutions in the construction and operation of the instrument.; The MAGIC collaboration would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP201571662-C2-2-P, FPA201790566REDC), the Indian Department of Atomic Energy, the Japanese JSPS and MEXT, and the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-153/28.08.2018 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" SEV-2016-0588 and SEV2015-0548 and Unidad de Excelencia "María de Maeztu" MDM-2014-0369, the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782, the University of Rijeka Project 13.12.1.3.02, the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382, and the Brazilian MCTIC, CNPq, and FAPERJ.; This publica, We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of similar to 27 Crab Units above 1 TeV was measured in very high energy (VHE) gamma-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE gamma-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE gamma-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy gamma-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsahovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare "decline" epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of similar to 25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (delta greater than or similar to 33) and the size of the emission region (delta R--1(B) less than or similar to 3.8 x 10(13) cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model., Ministerio de Economía y Competitividad (MINECO)/FEDER, Centro de Excelencia Severo Ochoa, Unidad de Excelencia María de Maeztu, U.S. Department of Energy Office of Science United States Department of Energy (DOE), U.S. National Science Foundation (NSF), Smithsonian Institution, NSERC in Canada Natural Sciences and Engineering Research Council of Canada, National Science Foundation (NSF), U.S. Department of Energy's Office of Science United States Department of Energy (DOE), National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility, German BMBF Federal Ministry of Education & Research (BMBF), MPG Max Planck Society, Italian INFN Istituto Nazionale di Fisica Nucleare, INAF, Swiss National Fund SNF Swiss National Science Foundation (SNSF), Indian Department of Atomic Energy, Japanese JSPS, Japanese MEXT, Bulgarian Ministry of Education and Science, National RI Roadmap Project, Croatian Science Foundation (HrZZ) Project, University of Rijeka Project, DFG Collaborative Research Centers German Research Foundation (DFG), Polish National Research Centre grant, Brazilian MCTIC, Brazilian CNPq National Council for Scientific and Technological Development (CNPq), Brazilian FAPERJ, NASA National Aeronautics & Space Administration, NSF National Science Foundation (NSF), NASA Fermi GI award, Russian RFBR foundation, Shota Rustaveli National Science Foundation, Fermi Guest Investigator Program, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2019. Artículo firmado por 22 autores. This work was supported by the Young Investigators Program of the Helmholtz Association, by the Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Center SFB 876 "Providing Information by Resource-Constrained Analysis", project C3 and by the European Commision through the ASTERICS Horizon2020 project (id 653477). We would like to thank the H.E.S.S., MAGIC, VERITAS, and FACT collaborations for releasing the data that were used. This work made use of astropy (Astropy Collaboration 2013) and sherpa (Freeman et al. 2001). The authors are indebted to Abelardo Moralejo and Hans Dembinski for their useful suggestions on the statistical and systematic uncertainty estimation. We are grateful to the anonymous referee for improving the paper with helpful comments., The analysis and combination of data from different gamma-ray instruments involves the use of collaboration proprietary software and case-by-case methods. The effort of defining a common data format for high-level data, namely event lists and instrument response functions (IRFs), has recently started for very-high-energy gamma-ray instruments, driven by the upcoming Cherenkov Telescope Array (CTA). In this work we implemented this prototypical data format for a small set of MAGIC, VERITAS, FACT, and H.E.S.S. Crab nebula observations, and we analyzed them with the open-source gammapy software package. By combining data from Fermi-LAT, and from four of the currently operating imaging atmospheric Cherenkov telescopes, we produced a joint maximum likelihood fit of the Crab nebula spectrum. Aspects of the statistical errors and the evaluation of systematic uncertainty are also commented upon, along with the release format of spectral measurements. The results presented in this work are obtained using open-access on-line assets that allow for a long-term reproducibility of the results., Unión Europea. H2020, Young Investigators Program of the Helmholtz Association, Deutsche Forschungsgemeinschaft (DFG), Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© EDP Sciencies. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, PA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009- 00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project 09/176, the University of Rijeka Project 13.12.1.3.02, the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 2016/22/M/ ST9/00382. Artículo firmado por más de diez autores., Spontaneous breaking of Lorentz symmetry at energies on the order of the Planck energy or lower is predicted by many quantum gravity theories, implying non-trivial dispersion relations for the photon in vacuum. Consequently, gamma-rays of different energies, emitted simultaneously from astrophysical sources, could accumulate measurable differences in their time of flight until they reach the Earth. Such tests have been carried out in the past using fast variations of gamma-ray flux from pulsars, and more recently from active galactic nuclei and gamma-ray bursts. We present new constraints studying the gamma-ray emission of the galactic Crab Pulsar, recently observed up to TeV energies by the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) collaboration. A profile likelihood analysis of pulsar events reconstructed for energies above 400 GeV finds no significant variation in arrival time as their energy increases. Ninety-five percent CL limits are obtained on the effective Lorentz invariance violating energy scale at the level of EQG₁ > 5.5 x 10¹⁷ Ge V (4.5 10¹⁷ Ge V) for a linear, and E(QG₂) > 5.9 x 10¹⁰ Ge V (5.3 10¹⁰ Ge V) for a quadratic scenario, for the subluminal and the superluminal cases, respectively. A substantial part of this study is dedicated to calibration of the test statistic, with respect to bias and coverage properties. Moreover, the limits take into account systematic uncertainties, which are found to worsen the statistical limits by about 36%–42%. Our constraints would have been much more stringent if the intrinsic pulse shape of the pulsar between 200 GeV and 400 GeV was understood in sufficient detail and allowed inclusion of events well below 400 GeV., Ministerio de Economía y Competitividad (MINECO), Centro de Excelencia "Severo Ochoa", Unidad de Excelencia "Maria de Maeztu", German B.M.B.F., German M.P.G., Italian INFN, Italian INAF, Swiss National Fund SNF, Croatian Science Foundation (HrZZ) Project, University of Rijeka Project, DFG Collaborative Research Centers, Polish MNiSzW grant, German Ministry for Education and Research (BMBF), Max Planck Society, German Research Foundation (DFG), French Ministry for Research, CNRS-IN2P3, Astroparticle Interdisciplinary Programme of the CNRS, UK Science and Technology Facilities Council (STFC), IPNP of the Charles University, Czech Science Foundation, Polish Ministry of Science and Higher Education, South African Department of Science and Technology, National Research Foundation, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

©Iop Publishing. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, – 10 – FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042- P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq and FAPERJ. The work of the author M. Vazquez Acosta is financed with grant RYC-2013-14660 of MINECO.Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq and FAPERJ. The work of the author M. Vazquez Acosta is financed with grant RYC-2013-14660 of MINECO. Articulo firmado por más de diez autores, The dwarf spheroidal galaxy Ursa Major II (UMaII) is believed to be one of the most dark-matter dominated systems among the Milky Way satellites and represents a suitable target for indirect dark matter (DM) searches. The MAGIC telescopes carried out a deep observation campaign on UMaII between 2014 and 2016, collecting almost one hundred hours of good-quality data. This campaign enlarges the pool of DM targets observed at very high energy (E ˃∼ 50 GeV) in search for signatures of DM annihilation in the wide mass range between ∼ to 100 GeV and ∼ to 100TeV. To this end, the data are analyzed with the full likelihood analysis, a method based on the exploitation of the spectral information of the recorded events for an optimal sensitivity to the explored DM models. We obtain constraints on the annihilation cross-section for different channels that are among the most robust and stringent achieved so far at the TeV mass scale from observations of dwarf satellite galaxies., Ministerio de Economía y Competitividad (MINECO), German BMBF, German MPG, Italian INFN, Italian INAF, Centro de Excelencia "Severo Ochoa, Unidad de Excelencia "Maria de Maeztu", Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© ESO 2018. Artículo firmado por 154 autores. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015-71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia "Severo Ochoa" SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia "María de Maeztu" MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq and FAPERJ. We would like to thank F. Rieger for useful discussions., We report on the detection of flaring activity from the Fanaroff-Riley I radio galaxy NGC 1275 in very-high-energy (VHE, E> 100 GeV) gamma rays with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes. The observations were performed between 2016 September and 2017 February, as part of a monitoring programme. The brightest outburst, with similar to 1.5 times the Crab Nebula flux above 100 GeV (C.U.), was observed during the night between 2016 December 31 and 2017 January 1. The flux is fifty times higher than the mean flux previously measured in two observational campaigns between 2009 October and 2010 February and between 2010 August and 2011 February. Significant variability of the day-by-day light curve was measured. The shortest flux-doubling timescale was found to be of (611 +/- 101) min. The spectra calculated for this period are harder and show a significant curvature with respect to the ones obtained in the previous campaigns. The combined spectrum of the MAGIC data during the strongest flare state and simultaneous data from the Fermi-LAT around 2017 January 1 follows a power law with an exponential cutoff at the energy (492 +/- 35) GeV. We further present simultaneous optical flux density measurements in the R-band obtained with the Kungliga Vetenskaps Akademien (KVA) telescope and investigate the correlation between the optical and gamma-ray emission. Due to possible internal pair-production, the fast flux variability constrains the Doppler factor to values that are inconsistent with a large viewing angle as observed in the radio band. We investigate different scenarios for the explanation of fast gamma-ray variability, namely emission from magnetospheric gaps, relativistic blobs propagating in the jet (mini-jets), or an external cloud (or star) entering the jet. We find that the only plausible model to account for the luminosities here observed would be the production of gamma rays in a magnetospheric gap around the central black hole, only i, Ministerio de Economía y Competitividad (MINECO)/FEDER, Unidad de Excelencia "Maria de Maeztu", Centro de Excelencia "Severo Ochoa", German BMBF, German MPG, Italian INFN, Italian INAF, Swiss National Fund SNF, Japanese JSPS, Japanese MEXT, Croatian Science Foundation (HrZZ) Project, Croatian University of Rijeka Project, DFG Collaborative Research Centers, Polish National Research Centre grant, Brazilian MCTIC, Brazilian CNPq, Brazilian FAPERJ, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. Artículo firmado por 157 autores. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015- 69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015- 69210-C6-2-R, FPA2015-69210-C6-4-R, FPA2015-69210-C6- 6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015- 71662-C2-2-P, CSD2009-00064), and the Japanese JSPS and MEXT is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2012-0234 and SEV-2015-0548, and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, by the Croatian Science Foundation (HrZZ) Project IP-2016-06- 9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq and FAPERJ. SI thanks support from JSPS KAKENHI Grant Number JP17K05460. The work of K.M. is partially supported by Alfred P. Sloan Foundation and NSF grant No. PHY-1620777., Fast radio bursts (FRBs) are bright flashes observed typically at GHz frequencies with millisecond duration, whose origin is likely extragalactic. Their nature remains mysterious, motivating searches for counterparts at other wavelengths. FRB 121102 is so far the only source known to repeatedly emit FRBs and is associated with a host galaxy at redshift z similar or equal to 0.193. We conducted simultaneous observations of FRB 121102 with the Arecibo and MAGIC telescopes during several epochs in 2016-2017. This allowed searches for millisecond time-scale burst emission in very-high-energy (VHE) gamma-rays as well as the optical band. While a total of five FRBs were detected during these observations, no VHE emission was detected, neither of a persistent nature nor burst-like associated with the FRBs. The average integral flux upper limits above 100 GeV at 95 percent confidence level are 6.6 x 10(-12) photons cm(-2) s(-1) (corresponding to luminosity L-VHE < 10 (45) erg s(-1)) over the entire observation period, and 1.2 x 10(-7) photons cm(-2) s(-1 )(L-VHE < 10 (49) erg s( -1)) over the total duration of the five FRBs. We constrain the optical U-band flux to be below 8.6 mJy at 5 sigma level for 1-ms intervals around the FRB arrival times. A bright burst with U-band flux 29 mJy and duration similar to 12 ms was detected 4.3 s before the arrival of one FRB. However, the probability of spuriously detecting such a signal within the sampled time space is 1.5 percent (2.2, post-trial), i.e. consistent with the expected background. We discuss the implications of the obtained upper limits for constraining FRB models., Ministerio de Economía y Competitividad (MINECO)/FEDER, Centro de Excelencia Severo Ochoa, Unidad de Excelencia 'Maria de Maeztu', German BMBF, German MPG, Italian INFN, Italian INAF, Swiss National Fund SNF, Japanese JSPS, MEXT, Croatian Science Foundation (HrZZ) Project, University of Rijeka Project, DFG Collaborative Research Centers, Polish National Research Centre, Brazilian MCTIC, CNPq, FAPERJ, JSPS KAKENHI, Alfred P. Sloan Foundation, NSF, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

We combine and extend the analyses of effective scalar, vector, Majorana and Dirac fermion Higgs portal models of dark matter (DM), in which DM couples to the Standard Model (SM) Higgs boson via an operator of the form (ODMHH)-H-dagger. For the fermion models, we take an admixture of scalar.. and pseudoscalar (psi) over bari gamma(5)psi interaction terms. For each model, we apply constraints on the parameter space based on the Planck measured DM relic density and the LHC limits on the Higgs invisible branching ratio. For the first time, we perform a consistent study of the indirect detection prospects for these models based on the WMAP7/Planck observations of the cosmic microwave background, a combined analysis of 15 dwarf spheroidal galaxies by Fermi-LAT and the upcoming Cherenkov Telescope Array (CTA). We also perform a correct treatment of the momentum-dependent direct search cross section that arises from the pseudoscalar interaction term in the fermionic DM theories. We find, in line with previous studies, that current and future direct search experiments such as LUX and XENON1T can exclude much of the parameter space, and we demonstrate that a joint observation in both indirect and direct searches is possible for high mass weakly interacting massive particles. In the case of a pure pseudoscalar interaction of a fermionic DM candidate, future gamma-ray searches are the only class of experiment capable of probing the high mass range of the theory., QC 20160715