Person: Miener, Tjark
Universidad Complutense de Madrid
Faculty / Institute
Now showing 1 - 10 of 24
PublicationAn intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state(Wiley, 2020-08) Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Miranda Pantoja, José Miguel; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...Extreme high-frequency BL Lacs (EHBL) feature their synchrotron peak of the broad-band spectral energy distribution (SED) at nu(s) >= 10(17) Hz. The BL Lac object 1ES 2344+514 was included in the EHBL family because of its impressive shift of the synchrotron peak in 1996. During the following years, the source appeared to be in a low state without showing any extreme behaviours. In 2016 August, 1ES 2344+514 was detected with the groundbased gamma-ray telescope FACT during a high gamma-ray state, triggering multiwavelength (MWL) observations. We studied the MWL light curves of 1ES 2344+514 during the 2016 flaring state, using data from radio to very-high-energy (VHE) gamma-rays taken with OVRO, KAIT, KVA, NOT, some telescopes of the GASP-WEBT collaboration at the Teide, Crimean, and St. Petersburg observatories, Swift-UVOT, Swift-XRT, Fermi-LAT, FACT, and MAGIC. With simultaneous observations of the flare, we built the broad-band SED and studied it in the framework of a leptonic and a hadronic model. The VHE gamma-ray observations show a flux level of 55 per cent of the Crab Nebula flux above 300 GeV, similar to the historical maximum of 1995. The combination of MAGIC and Fermi-LAT spectra provides an unprecedented characterization of the inverse-Compton peak for this object during a flaring episode. The Gamma index of the intrinsic spectrum in the VHE gamma-ray band is 2.04 +/- 0.12(stat) +/- 0.15(sys). We find the source in an extreme state with a shift of the position of the synchrotron peak to frequencies above or equal to 1018 Hz. PublicationDetection of the Geminga pulsar with MAGIC hints at a power-law tail emission beyond 15 GeV(EDP Sciencies, 2020-11-20) Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, LabWe report the detection of pulsed gamma-ray emission from the Geminga pulsar (PSR J0633+1746) between 15 GeV and 75 GeV. This is the first time a middle-aged pulsar has been detected up to these energies. Observations were carried out with the MAGIC telescopes between 2017 and 2019 using the low-energy threshold Sum-Trigger-II system. After quality selection cuts, similar to 80 h of observational data were used for this analysis. To compare with the emission at lower energies below the sensitivity range of MAGIC, 11 years of Fermi-LAT data above 100 MeV were also analysed. From the two pulses per rotation seen by Fermi-LAT, only the second one, P2, is detected in the MAGIC energy range, with a significance of 6.3 sigma. The spectrum measured by MAGIC is well-represented by a simple power law of spectral index Gamma =5.62 +/- 0.54, which smoothly extends the Fermi-LAT spectrum. A joint fit to MAGIC and Fermi-LAT data rules out the existence of a sub-exponential cut-off in the combined energy range at the 3.6 sigma significance level. The power-law tail emission detected by MAGIC is interpreted as the transition from curvature radiation to Inverse Compton Scattering of particles accelerated in the northern outer gap. PublicationBounds on Lorentz Invariance Violation from MAGIC Observation of GRB 190114C(American Physical Society, 2020-07-09) Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...On January 14, 2019, the Major Atmospheric Gamma Imaging Cherenkov telescopes detected GRB 190114C above 0.2 TeV, recording the most energetic photons ever observed from a gamma-ray burst. We use this unique observation to probe an energy dependence of the speed of light in vacuo for photons as predicted by several quantum gravity models. Based on a set of assumptions on the possible intrinsic spectral and temporal evolution, we obtain competitive lower limits on the quadratic leading order of speed of light modification. PublicationvFAB: Facilitando el método de clase invertida mediante la producción de material audiovisual aplicado a los seminarios de Física Aplicada a la Biología(2023-07-12) Nieto Castaño, Daniel; Domínguez Díaz, Alberto; Barrio Uña, Juan Abel; Contreras González, José Luis; Láinez Lezáun, María; Miener, TjarkEl proyecto "vídeo Física Aplicada a la Biología" (vFAB) pretende facilitar el método de clase invertida mediante la producción de material audiovisual aplicado a los seminarios de dicha asignatura. Esta memoria resume el desarrollo del proyecto durante el curso académico 2022/2023, describiendo los materiales confeccionados, su despliegue y utilización en el marco de la clase invertida, y comentando los resultados obtenidos. PublicationProton acceleration in thermonuclear nova explosions revealed by gamma rays(Nature Publishing Group, 2022) Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Mas Aguilar, Alvaro; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; otros, ...Classical novae are cataclysmic binary star systems in which the matter of a companion star is accreted on a white dwarf(1,2). Accumulation of hydrogen in a layer eventually causes a thermonuclear explosion on the surface of the white dwarf(3), brightening the white dwarf to similar to 10(5) solar luminosities and triggering ejection of the accumulated matter. Novae provide the extreme conditions required to accelerate particles, electrons or protons, to high energies. Here we present the detection of gamma rays by the MAGIC telescopes from the 2021 outburst of RS Ophiuchi, a recurrent nova with a red giant companion, which allowed us to accurately characterize the emission from a nova in the 60 GeV to 250 GeV energy range. The theoretical interpretation of the combined Fermi LAT and MAGIC data suggests that protons are accelerated to hundreds of gigaelectronvolts in the nova shock. Such protons should create bubbles of enhanced cosmic ray density, of the order of 10 pc, from the recurrent novae. PublicationHESS and MAGIC observations of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 in May 2016(EDP Sciencies, 2021-04-07) Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behaviour and it is one of only a few FSRQs detected in very-high-energy (VHE, E>100 GeV) gamma rays. The VHE gamma -ray observations with H.E.S.S. and MAGIC in late May and early June 2016 resulted in the detection of an unprecedented flare, which revealed, for the first time, VHE gamma -ray intranight variability for this source. While a common variability timescale of 1.5 h has been found, there is a significant deviation near the end of the flare, with a timescale of similar to 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, a curvature was detected in the VHE gamma -ray spectrum of PKS 1510-089, which can be fully explained by the absorption on the part of the extragalactic background light. Optical R-band observations with ATOM revealed a counterpart of the gamma -ray flare, even though the detailed flux evolution differs from the VHE gamma -ray light curve. Interestingly, a steep flux decrease was observed at the same time as the cessation of the VHE gamma -ray flare. In the high-energy (HE, E> 100 MeV) gamma -ray band, only a moderate flux increase was observed with Fermi-LAT, while the HE gamma -ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the gamma -ray spectrum indicates that the emission region is located outside of the BLR. Radio very-long-baseline interferometry observations reveal a fast-moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located similar to 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this is indeed a true correlation, the VHE gamma rays must have been produced far down in the jet, where turbulent plasma crosses a standing shock. PublicationStudy of the GeV to TeV morphology of the gamma Cygni SNR (G 78.2+2.1) with MAGIC and Fermi-LAT: Evidence for cosmic ray escape(EDP Sciencies, 2023-01-30) Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...Context. Diffusive shock acceleration (DSA) is the most promising mechanism that accelerates Galactic cosmic rays (CRs) in the shocks of supernova remnants (SNRs). It is based on particles scattering caused by turbulence ahead and behind the shock. The turbulence upstream is supposedly generated by the CRs, but this process is not well understood. The dominant mechanism may depend on the evolutionary state of the shock and can be studied via the CRs escaping upstream into the interstellar medium (ISM). Aims. Previous observations of the gamma Cygni SNR showed a difference in morphology between GeV and TeV energies. Since this SNR has the right age and is at the evolutionary stage for a significant fraction of CRs to escape, our aim is to understand gamma-ray emission in the vicinity of the gamma Cygni SNR. Methods. We observed the region of the gamma Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov telescopes between 2015 May and 2017 September recording 87 h of good-quality data. Additionally, we analysed Fermi-LAT data to study the energy dependence of the morphology as well as the energy spectrum in the GeV to TeV range. The energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the CR escape process and their gamma-ray generation. Results. The MAGIC and Fermi-LAT data allowed us to identify three emission regions that can be associated with the SNR and that dominate at different energies. Our hadronic emission model accounts well for the morphology and energy spectrum of all source components. It constrains the time-dependence of the maximum energy of the CRs at the shock, the time-dependence of the level of turbulence, and the diffusion coefficient immediately outside the SNR shock. While in agreement with the standard picture of DSA, the time-dependence of the maximum energy was found to be steeper than predicted, and the level of turbulence was found to change over the lifetime of the SNR. PublicationMultiwavelength Observations of the Blazar VER J0521+211 during an Elevated TeV Gamma-Ray State(IOP Publishing, 2022-06-01) Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; López Moya, Marcos; Mas Aguilar, Alvaro; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; otros, ...We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 +/- 0.4) x 10(-7) photons m(-2) s(-1), or similar to 37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be z <= 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object. PublicationInvestigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017(EDP Sciencies, 2021-11-29) Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...Aims. We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. Methods. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. Results. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e., orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3 sigma. A VHE flare observed on MJD 57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from gamma(min)' = 2 x 10(4) to gamma(max)' = 6 x 10(5). PublicationUnraveling the Complex Behavior of Mrk 421 with Simultaneous X-Ray and VHE Observations during an Extreme Flaring Activity in 2013 April(University Chicago Press, 2020-06) Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miener, Tjark; Morcuende, D.; Peñil del Campo, Pablo; Saha, Lab; otros, ...We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses, among others, data from GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), Swift, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Large Area Telescope, Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma Imaging Cherenkov (MAGIC). The large blazar activity and the 43 hr of simultaneous NuSTAR and MAGIC/VERITAS observations permitted variability studies on 15 minute time bins over three X-ray bands (3-7 keV, 7-30 keV, and 30-80 keV) and three very-high-energy (VHE; >0.1 TeV) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV, and >0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all of the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-rays and the VHE gamma-rays. The three VHE bands and the three X-ray bands are positively correlated with no time lag, but the strength and characteristics of the correlation change substantially over time and across energy bands. Our findings favor multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer.