Person: Domínguez Díaz, Alberto
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First Name
Alberto
Last Name
Domínguez Díaz
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Identifiers
31 results
Search Results
Now showing 1 - 10 of 31
- PublicationThe Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope: Data Release 3(University Chicago Press, 2022) Domínguez Díaz, Alberto; otros, ...An incremental version of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope is presented. This version (4LAC-DR3) derives from the third data release of the 4FGL catalog based on 12 yr of E > 50 MeV gamma-ray data, where the spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates and four radio galaxies. We describe the properties of the new sample and outline changes affecting the previously published one. We also introduce two new parameters in this release, namely the peak energy of the SED high-energy component and the corresponding flux. These parameters allow an assessment of the Compton dominance, the ratio of the inverse-Compton to the synchrotron-peak luminosities, without relying on X-ray data.
- PublicationSensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre(Iop Publishing, 2021-01) Arqueros Martínez, Fernando; Baquero Larriva, Orlando Andrés; Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; López Moya, Marcos; Miener, Tjark; Morcuende Parrilla, Daniel; Nieto Castaño, Daniel; Rosado Vélez, Jaime; Tejedor Álvarez, Luis Ángel; otros, ...We provide an updated assessment of the power of the Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at the TeV scale, via the associated gamma-ray signal from pair-annihilating dark matter particles in the region around the Galactic centre. We find that CTA will open a new window of discovery potential, significantly extending the range of robustly testable models given a standard cuspy profile of the dark matter density distribution. Importantly, even for a cored profile, the projected sensitivity of CTA will be sufficient to probe various well-motivated models of thermally produced dark matter at the TeV scale. This is due to CTA's unprecedented sensitivity, angular and energy resolutions, and the planned observational strategy. The survey of the inner Galaxy will cover a much larger region than corresponding previous observational campaigns with imaging atmospheric Cherenkov telescopes. CTA will map with unprecedented precision the large-scale diffuse emission in high-energy gamma rays, constituting a background for dark matter searches for which we adopt state-of-the-art models based on current data. Throughout our analysis, we use up-to-date event reconstruction Monte Carlo tools developed by the CTA consortium, and pay special attention to quantifying the level of instrumental systematic uncertainties, as well as background template systematic errors, required to probe thermally produced dark matter at these energies.
- PublicationDeep observations of the globular cluster M15 with the MAGIC telescopes(Wiley, 2019-04) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, Lab; otros, ...A population of globular clusters (GCs) has been recently established by the Fermi-LAT telescope as a new class of GeV gamma-ray sources. Leptons accelerated to TeV energies, in the inner magnetospheres of MSPs or in their wind regions, should produce gamma-rays through the inverse Compton scattering in the dense radiation field from the huge population of stars. We have conducted deep observations of the GC M15 with the MAGIC telescopes and used 165 h in order to search for gamma-ray emission. A strong upper limit on the TeV gamma-ray flux < 3.2 x 10(-13) cm(-2) s(-1) above 300 GeV ( < 0.26 per cent of the Crab nebula flux) has been obtained. We interpret this limit as a constraint on the efficiency of the acceleration of leptons in the magnetospheres of the MSPs. We constrain the injection rate of relativistic leptons, eta(e), from the MSPs magnetospheres and their surrounding. We conclude that eta(e) must be lower than expected from the modelling of high-energy processes in MSP inner magnetospheres. For leptons accelerated with the power-law spectrum in the MSP wind regions, eta(e) is constrained to be much lower than derived for the wind regions around classical pulsars. These constraints are valid for the expected range of magnetic field strengths within the GC and for the range of likely energies of leptons injected from the inner magnetospheres, provided that the leptons are not removed from the GC very efficiently due to advection process. We discuss consequences of these constraints for the models of radiation processes around millisecond pulsars.
- PublicationThe Blazar TXS 0506+056 Associated with a High-energy Neutrino: Insights into Extragalactic Jets and Cosmic-Ray Acceleration(IOP Publishing Ltd, 2018-08-10) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Victoria; Hoang, Kim Dinh; López Moya, Marcos; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, LabA neutrino with energy similar to 290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS. 0506+056 during enhanced gamma-ray activity, with chance coincidence being rejected at similar to 3 sigma level. We monitored the object in the very-high-energy (VHE) band with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for similar to 41 hr from 1.3 to 40.4 days after the neutrino detection. Day-timescale variability is clearly resolved. We interpret the quasi-simultaneous neutrino and broadband electromagnetic observations with a novel one-zone lepto-hadronic model, based on interactions of electrons and protons co-accelerated in the jet with external photons originating from a slow-moving plasma sheath surrounding the faster jet spine. We can reproduce the multiwavelength spectra of TXS 0506+056 with neutrino rate and energy compatible with IceCube-170922A, and with plausible values for the jet power of similar to 10(45) - 4 x 10(46) erg s(-1). The steep spectrum observed by MAGIC is concordant with internal gamma gamma absorption above similar to 100 GeV entailed by photohadronic production of a similar to 290 TeV neutrino, corroborating a genuine connection between the multi-messenger signals. In contrast to previous predictions of predominantly hadronic emission from neutrino sources, the gamma-rays can be mostly ascribed to inverse Compton upscattering of external photons by accelerated electrons. The X-ray and VHE bands provide crucial constraints on the emission from both accelerated electrons and protons. We infer that the maximum energy of protons in the jet comoving frame can be in the range similar to 10(14) - 10(18) eV.
- PublicationDiscovery of TeV γ-ray emission from the neighbourhood of the supernova remnant G24.7+0.6 by MAGIC(Wiley, 2019-03) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, Lab; otros, ...SNR G24.7+0.6 is a 9.5 kyrs radio and gamma-ray supernova remnant evolving in a dense medium. In the GeV regime, SNR G24.7+0.6 (3FHL J1834.1-0706e/FGFS J1834.1-0706) shows a hard spectral index (Gamma similar to 2) up to 200 GeV, which makes it a good candidate to be observed with Cherenkov telescopes such as MAGIC. We observed the field of view of SNR G24.7+0.6 with the MAGIC telescopes for a total of 31 h. We detect very high-energy gamma-ray emission from an extended source located 0.34 degrees away from the centre of the radio SNR. The new source, named MAGIC J1835-069 is detected up to 5 TeV, and its spectrum is well-represented by a power-law function with spectral index of 2.74 +/- 0.08. The complexity of the region makes the identification of the origin of the very high-energy emission difficult; however, the spectral agreement with the LAT source and overlapping position at less than 1.5 sigma point to a common origin. We analysed 8 yr of Fermi-LAT data to extend the spectrum of the source down to 60 MeV. Fermi-LAT and MAGIC spectra overlap within errors and the global broad-band spectrum is described by a power law with exponential cut-off at 1.9 +/- 0.5 TeV. The detected gamma-ray emission can be interpreted as the results of proton-proton interaction between the supernova and the CO-rich surrounding.
- PublicationConstraining dark matter lifetime with a deep gamma-ray survey of the Perseus galaxy cluster with MAGIC(Elsevier B.V., 2018-12) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, Lab; otros, ...Clusters of galaxies are the largest known gravitationally bound structures in the Universe, with masses around 10(15)M circle dot, most of it in the form of dark matter. The ground-based Imaging Atmospheric Cherenkov Telescope MAGIC made a deep survey of the Perseus cluster of galaxies using almost 400 h of data recorded between 2009 and 2017. This is the deepest observational campaign so far on a cluster of galaxies in the very high energy range. We search for gamma-ray signals from dark matter particles in the mass range between 200 GeV and 200 TeV decaying into standard model pairs. We apply an analysis optimized for the spectral and morphological features expected from dark matter decays and find no evidence of decaying dark matter. From this, we conclude that dark matter particles have a decay lifetime longer than similar to 10(26) s in all considered channels. Our results improve previous lower limits found by MAGIC and represent the strongest limits on decaying dark matter particles from ground-based gamma-ray instruments. (C) 2018 Elsevier B.V. All rights reserved.
- PublicationDetection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state(EDP Sciences S A, 2018-09-13) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Victoria; López Moya, Marcos; Nievas Rosillo, Mireia; otros, ...Aims. The very high energy (VHE greater than or similar to 100 GeV) gamma-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z >= 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and gamma-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy gamma-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100 degrees. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL).
- PublicationPeriastron Observations of TeV Gamma-Ray Emission from a Binary System with a 50-year Period(IOP Publishing Ltd, 2018-11-01) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Victoria; Hoang, Kim Dinh; López Moya, Marcos; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, LabWe report on observations of the pulsar/Be star binary system PSR J2032+4127/MT91 213 in the energy range between 100 GeV and 20 TeV with the Very Energetic Radiation Imaging Telescope Array and Major Atmospheric Gamma Imaging Cherenkov telescope arrays. The binary orbit has a period of approximately 50 years, with the most recent periastron occurring on 2017 November 13. Our observations span from 18 months prior to periastron to one month after. A new point-like gamma-ray source is detected, coincident with the location of PSR J2032+4127/MT91 213. The gamma-ray light curve and spectrum are well characterized over the periastron passage. The flux is variable over at least an order of magnitude, peaking at periastron, thus providing a firm association of the TeV source with the pulsar/Be star system. Observations prior to periastron show a cutoff in the spectrum at an energy around 0.5 TeV. This result adds a new member to the small population of known TeV binaries, and it identifies only the second source of this class in which the nature and properties of the compact object are firmly established. We compare the gamma-ray results with the light curve measured with the X-ray Telescope on board the Neil Gehrels Swift Observatory and with the predictions of recent theoretical models of the system. We conclude that significant revision of the models is required to explain the details of the emission that we have observed, and we discuss the relationship between the binary system and the overlapping steady extended source, TeV J2032+4130.
- PublicationModeling the Extragalactic Background Light and the Cosmic Star Formation History.(IOP Publishing, 2022-12-01) Finke, Justin D.; Ajello, Marco; Domínguez Díaz, Alberto; Desai, Abhishek; Hartmann, Dieter H.; Paliya, Valdehi S.; Saldaña López, AlbertoWe present an updated model for the extragalactic background light (EBL) from stars and dust, over wavelengths approximate to 0.1-1000 mu m. This model uses accurate theoretical stellar spectra, and tracks the evolution of star formation, stellar mass density, metallicity, and interstellar dust extinction and emission in the universe with redshift. Dust emission components are treated self-consistently, with stellar light absorbed by dust reradiated in the infrared as three blackbody components. We fit our model, with free parameters associated with star formation rate and dust extinction and emission, to a wide variety of data: luminosity density, stellar mass density, and dust extinction data from galaxy surveys; and gamma-ray absorption optical depth data from gamma-ray telescopes. Our results strongly constraint the star formation rate density and dust photon escape fraction of the universe out to redshift z = 10, about 90% of the history of the universe. We find our model result is, in some cases, below lower limits on the z = 0 EBL intensity, and below some low-z gamma-ray absorption measurements.
- PublicationDiscovery of TeV γ-ray emission from the neighbourhood of the supernova remnant G24.7+0.6 by MAGIC(Wiley, 2019-03) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Mª Victoria; Hoang, Kim Dinh; López Moya, Marcos; Nievas Rosillo, Mireia; Peñil del Campo, Pablo; Saha, Lab; otros, ...SNR G24.7+0.6 is a 9.5 kyrs radio and gamma-ray supernova remnant evolving in a dense medium. In the GeV regime, SNR G24.7+0.6 (3FHL J1834.1-0706e/FGFS J1834.1-0706) shows a hard spectral index (Gamma similar to 2) up to 200 GeV, which makes it a good candidate to be observed with Cherenkov telescopes such as MAGIC. We observed the field of view of SNR G24.7+0.6 with the MAGIC telescopes for a total of 31 h. We detect very high-energy gamma-ray emission from an extended source located 0.34 degrees away from the centre of the radio SNR. The new source, named MAGIC J1835-069 is detected up to 5 TeV, and its spectrum is well-represented by a power-law function with spectral index of 2.74 +/- 0.08. The complexity of the region makes the identification of the origin of the very high-energy emission difficult; however, the spectral agreement with the LAT source and overlapping position at less than 1.5 sigma point to a common origin. We analysed 8 yr of Fermi-LAT data to extend the spectrum of the source down to 60 MeV. Fermi-LAT and MAGIC spectra overlap within errors and the global broad-band spectrum is described by a power law with exponential cut-off at 1.9 +/- 0.5 TeV. The detected gamma-ray emission can be interpreted as the results of proton-proton interaction between the supernova and the CO-rich surrounding.