López Moya, Marcos

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First Name
Last Name
López Moya
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Estructura de la Materia, Física Térmica y Electrónica
Física Atómica, Molecular y Nuclear
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Now showing 1 - 10 of 158
  • Publication
    Search for very high energy gamma-rays from the z=0.896 quasar 4C+55.17 with the MAGIC telescopes
    (Wiley, 2014-05) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Satalecka, Konstanzja; Scapin, Valeria
    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.
  • Publication
    Very high energy gamma-ray radiation from the stellar mass black hole binary Cygnus X-1
    (IOP Publishing, 2007-08-10) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nieto, Daniel
    We report on the results from the observations in the very high energy band ( VHE; GeV) of the black E = 100 g hole X- ray binary ( BHXB) Cygnus X- 1. The observations were performed with the MAGIC telescope, for a total of 40 hr during 26 nights, spanning the period between 2006 June and November. Searches for steady gamma - ray signals yielded no positive result, and upper limits to the integral flux ranging between 1% and 2% of the Crab Nebula flux, depending on the energy, have been established. We also analyzed each observation night independently, obtaining evidence of gamma- ray signals at the 4.0 j significance level ( 3.2 j after trial correction) for 154 minutes of effective on- time ( EOT) on September 24 between 20: 58 and 23: 41 UTC, coinciding with an X- ray flare seen by RXTE, Swift, and INTEGRAL. A search for faster- varying signals within a night resulted in an excess with a significance of 4.9 j ( 4.1 j after trial correction) for 79 minutes EOT between 22: 17 and 23: 41 UTC. The measured excess is compatible with a pointlike source at the position of Cygnus X- 1 and excludes the nearby radio nebula powered by its relativistic jet. The differential energy spectrum is well fitted by an unbroken power law described as dN/(dA dt dE) = ( 2.3 +/- 0.6)* 10 ( E/1TeV). This is the first experimental evidence of VHE emission from a stellar mass black hole and therefore from a confirmed accreting X- ray binary.
  • Publication
    An 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.
  • Publication
    Detection 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, Lab
    We 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.
  • Publication
    Constraining very-high-energy and optical emission from FRB 121102 with the MAGIC telescopes
    (Oxford Univ Press, 2018-12) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca Gonzáez, Victoria; Hoang, Kim Dinh; López Moya, Marcos; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, Lab; otros, ...
    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.
  • Publication
    Probing the very high energy gamma-ray spectral curvature in the blazar PG 1553+113 with the MAGIC telescopes
    (Oxford University Press, 2015-07-11) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Satalecka, Konstanzja; Scapin, Valeria
    PG 1553+113 is a very-high-energy (VHE, E > 100 GeV) γ-ray emitter classified as a BL Lac object. Its redshift is constrained by intergalactic absorption lines in the range 0.4 < z < 0.58. The MAGIC telescopes have monitored the source’s activity since 2005. In early 2012, PG 1553+113 was found in a high-state, and later, in April of the same year, the source reached its highest VHE flux state detected so far. Simultaneous observations carried out in X-rays during 2012 April show similar flaring behaviour. In contrast, the γ-ray flux at E < 100 GeV observed by Fermi-LAT is compatible with steady emission. In this paper, a detailed study of the flaring state is presented. The VHE spectrum shows clear curvature, being well fitted either by a power law with an exponential cut-off or by a log-parabola. A simple power-law fit hypothesis for the observed shape of the PG 1553+113 VHE γ-ray spectrum is rejected with a high significance (fit probability P=2.6 ×10−6). The observed curvature is compatible with the extragalactic background light (EBL) imprint predicted by current generation EBL models assuming a redshift z ∼ 0.4. New constraints on the redshift are derived from the VHE spectrum. These constraints are compatible with previous limits and suggest that the source is most likely located around the optical lower limit, z = 0.4, based on the detection of Lyα absorption. Finally, we find that the synchrotron self-Compton (SSC) model gives a satisfactory description of the observed multi-wavelength spectral energy distribution during the flare.
  • Publication
    Magic observations of the unidentified gamma-ray source TEV J2032+4130
    (IOP Publishing, 2008-03-01) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nieto, Daniel
    We observed the first known very high energy (VHE) gamma-ray-emitting unidentified source, TeV J2032 + 4130, for 94 hr with the MAGIC telescope. The source was detected with a significance of 5.6 sigma. The flux, position, and angular extension are compatible with the previous ones measured by the HEGRA telescope system 5 years ago. The integral flux amounts to (4.5 +/- 0.3(stat)+/- 0.35(sys)) x 10 (- 13) photons cm(-2) s(-1) above 1 TeV. The source energy spectrum, obtained with the lowest energy threshold to date, is compatible with a single power law with a hard photon index of Gamma= - 2.0 +/- 0.3(stat)+/- 0.2(sys). Miranda Pantka
  • Publication
    Observations of Markarian 421 with the MAGIC telescope
    (IOP Publishing, 2007-07-01) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel
    The MAGIC telescope took data of very high energy gamma-ray emission from the blazar Markarian 421 ( Mrk 421) between 2004 November and 2005 April. We present a combined analysis of data samples recorded under different observational conditions, down to gamma- ray energies of 100 GeV. The flux was found to vary between 0.5 and 2 crab ( integrated above 200 GeV), considered a low state when compared to known data. Although the flux varied day by day, no short-term variability was observed, although there is some indication that not all nights show an equally quiescent state. The results at higher energies were found to be consistent with previous observations. A clear correlation is observed between gamma-ray and X-ray fluxes, whereas no significant correlation between gamma-ray and optical data is seen. The spectral energy distribution between 100 GeVand 3 TeV shows a clear deviation from a power law, more clearly and at lower flux than previous observations at higher energies. The deviation persists after correcting for the effect of attenuation by the extragalactic background light, and most likely is source- inherent. There is a rather clear indication of an inverse Compton peak around 100 GeV. The spectral energy distribution of Mrk 421 can be fitted by a one-zone synchrotron self-Compton model, suggesting once again a leptonic origin of the very high energy gamma-ray emission from this blazar.
  • Publication
    Very haigh energy gamma-Rays from the universe's middle age: detection of the z=0.940 blazar PKS 1441+25 with Magic
    (IOP Publishing, 2015-12-20) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Miguel; Satalecka, Konstanzja; Otros, ...
    The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218 +357 (z = 0.944), PKS 1441+25 is the most distant very high energy (VHE) blazar detected to date. The observations were triggered by an outburst in 2015 April seen at GeV energies with the Large Area Telescope on board Fermi. Multi wavelength observations suggest a subdivision of the high state into two distinct flux states. In the band covered by MAGIC, the variability timescale is estimated to be 6.4 ± 1.9 days. Modeling the broadband spectral energy distribution with an external Compton model, the location of the emitting region is understood as originating in the jet outside the broad-line region (BLR) during the period of high activity, while being partially within the BLR during the period of low (typical) activity. The observed VHE spectrum during the highest activity is used to probe the extragalactic background light at an unprecedented distance scale for ground-based gamma-ray astronomy.
  • Publication
    First NuSTAR observations of MRK 501 within a radio to TeV multi-instrument capaign
    (American Astronomical Society, 2015-10-10) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia; Satalecka, Konstanzja; Scapin, Valeria; Otros, ...
    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.