General
Description
Active Galactic Nuclei (AGN) are characterized by a strong emission coming from a very compact region (only few pcs) at the galaxy center. Blazars form a class of AGN, characterized by high luminosity in a broad frequency range, from radiofrequencies to high energies (X-rays and γ-rays), as well as extreme variability and high polarization at optical and near-infrared and radio wavelengths. The broad-band spectral energy distribution shows two bumps: the low-frequency one, from radio to optical/Xrays; and the high-frequency one, from X-rays to γ-rays. The most accepted scenario to explain the observed properties suggests that the emission is coming from a jet of accelerated relativistic particles, closely aligned with the line of sight and originating at the proximity of a supermassive black hole. In this way, the jet emission is strongly amplified and it exceeds any other kind of radiation coming from the galaxy. Synchrotron emission explains the low-frequency bump, whereas leptonic and hadronic models are competing to describe the high-energy bump.
Nowadays, a respectable number of blazers is being monitored daily by the high-energy space observatories, Fermi and AGILE. Blazers also dominate the Universe in the very high energy gamma-ray band (E>100 GeV), which observations are carried out from the ground using Cherenkov telescopes. Hence follow-up programs to simultaneously cover a broad frequency range are mandatory in order to learn more about the unpredictable flux variability observed in ths type of active nuclei and furthermore to try understanding in more detail the physical processes taking place.
In this project two aspects will be covered: on one side, follow-up observations in the optical and near-infrared ranges will be provided, using the telescopes available at the Teide and Roque de Los Muchachos observatories. These observations are carried out within the framework of a more extense collaboration, the GASP-WEBT, which comprises about 30 other observatories. Remarkably, this is the only way to catch and monitor in detail all phases (rising, peak and falling) of correlated flares, which are the test-bed for the theoretical models for high-energy emission; On the other side, long term series of data (several years) taken at different energy ranges will be analized to search for correlations between bands and also any kind of periodicities which may indicate jet-precession, binary black-holes or any other mechanism. Additional insight can be gained by analyzing a number of flares in different targets but, due to the unpredictable nature of such events, this has to be interpreted in statistical terms.
Members
Principal investigator
José Antonio
Acosta Pulido
Project staff
María Jesús
Arevalo Morales
Josefa
Becerra González
Carlos
Lázaro Hernando
Jorge
Otero Santos
Collaborators
Jorge Andrés
Pérez Prieto
Dr.
M.I. Carnerero Martín
Dr.
C.M. Raiteri
Dr.
A. Capetti
Dr.
F. D'Ammando
Dr.
N. Castro Segura
Results
- The host galaxy morphology of the active nucleus Pks 1502+036 is found to correspond to an elliptical (D'Ammando et al 2018). This active nucleus is a powerful gamma ray emitter which implies the presence of a very massive black hole, contrary to the expected from its spectroscopic classification.
- First redshift determination of the very high energy gamma-ray extreme blazar PGC 2402248 from optical spectroscopy obtained using OSIRIS at GTC (Becerra et al, 2018, ATel 11621). This blazar has been previously detected by MAGIC at very high energy (E > 100GeV).
- The analysis of the light curves in the optical range of two blazars reveals a periodic behaviour with cadence of few years.
Scientific activity
Related publications
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Systematic Search for γ-Ray Periodicity in Active Galactic Nuclei Detected by the Fermi Large Area TelescopeWe use nine years of γ-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves (LCs) of more than 2000 active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different techniques are used, which are organized in an automatic periodicity-search pipeline, in order to search for evidence ofPeñil, P. et al.
Advertised on:
62020 -
Optical spectral characterization of the TeV extreme blazar 2WHSP J073326.7+515354The emission from the relativistic jets in blazars usually outshines their host galaxies, challenging the determination of their distances and the characterization of the stellar population. The situation becomes more favourable in the case of the extreme blazars (EHBLs), for which the bulk of the emission of the relativistic jets is emitted atBecerra González, J. et al.
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42020 -
Unveiling the monster heart: unbeamed properties of blazar 4C 71.074C 71.07 is a high-redshift blazar whose optical radiation is dominated by quasar-like nuclear emission. We here present the results of a spectroscopic monitoring of the source to study its unbeamed properties. We obtained 24 optical spectra at the Nordic Optical Telescope and William Herschel Telescope and 3 near-infrared spectra at the TelescopioRaiteri, C. M. et al.
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42020 -
Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38We report on quasi-periodic variability found in two blazars included in the Steward Observatory Blazar Monitoring data sample: the BL Lac object 3C 66A and the Flat Spectrum Radio Quasar B2 1633+38. We collect optical photometric and polarimetric data in V and R bands of these sources from different observatories: St. Petersburg UniversityOtero-Santos, J. et al.
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32020 -
Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radioWe report the results of decade-long (2008-2018) γ-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ-ray light curves correlate well, with no delay ≳ 3 h, implying general cospatiality of the emission regions. The γ-ray-optical flux-fluxLarionov, V. M. et al.
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32020 -
Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013-2017We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as wellD'Ammando, F. et al.
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122019 -
The beamed jet and quasar core of the distant blazar 4C 71.07The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a 2-yr multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented byRaiteri, C. M. et al.
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102019 -
The afterglow and kilonova of the short GRB 160821BGRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of 16 kpc from the galaxy's center. We present X-ray, optical/nIR, and radio observations of its counterpart and model them with two distinct componentsTroja, E. et al.
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102019 -
A compact jet at the infrared heart of the prototypical low-luminosity AGN in NGC 1052The feeble radiative efficiency characteristic of Low-Luminosity Active Galactic Nuclei (LLAGNs) is ascribed to a sub-Eddington accretion rate, typically at log (Lbol/Ledd) ≲ -3. At the finest angular resolutions that are attainable nowadays using mid-infrared (mid-IR) interferometry, the prototypical LLAGN in NGC 1052 remains unresolved down to 5Fernández-Ontiveros, J. A. et al.
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62019 -
The Weakening Outburst of the Young Eruptive Star V582 AurV582 Aur is a pre-main-sequence FU Orionis type eruptive star, which entered a brightness minimum in 2016 March due to changes in the line-of-sight extinction. Here, we present and analyze new optical B, V, R C , and I C band multiepoch observations and new near-infrared J, H, and K S band photometric measurements from 2018 January–2019 FebruaryZsidi, G. et al.
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32019 -
Extreme HBL behavior of Markarian 501 during 2012Aims: We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods: We organized a multiwavelength campaign to take place betweenDi Pierro, F. et al.
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122018 -
AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburstContext. The flat-spectrum radio quasar 4C +71.07 is a high-redshift (z = 2.172), γ-loud blazar whose optical emission is dominated by thermal radiation from the accretion disc. Aims: 4C +71.07 has been detected in outburst twice by the AGILE γ-ray satellite during the period from the end of October to mid-November 2015, when it reached a γ-rayVercellone, S. et al.
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12019 -
The outbursting protostar 2MASS 22352345 + 7517076 and its environmentWe studied the Class I protostar 2MASS 22352345 + 7517076 whose dramatic brightening between the IRAS, Akari, and WISE surveys was reported by Onozato et al. 2MASS 22352345+7517076 is a member of a small group of low-mass young stellar objects, associated with IRAS 22343 + 7501 in the molecular cloud Lynds 1251. The IRAS, ISO, Spitzer, AkariKun, M. et al.
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32019 -
Multi-wavelength characterization of the blazar S5 0716+714 during an unprecedented outburst phaseContext. The BL Lac object S5 0716+714, a highly variable blazar, underwent an impressive outburst in January 2015 (Phase A), followed by minor activity in February (Phase B). The MAGIC observations were triggered by the optical flux observed in Phase A, corresponding to the brightest ever reported state of the source in the R-band. Aims.TheAhnen, M. L. et al.
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112018 -
Detection of persistent VHE gamma-ray emission from PKS 1510-089 by the MAGIC telescopes during low states between 2012 and 2017Context. PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. To date, very high-energy (VHE, > 100 GeV) emission has been observed from this source either during long high states of optical and GeV activity or during short flares. Aims: We search for low-state VHE gamma-ray emission from PKS 1510-089. WeAcciari, V. A. et al.
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112018 -
Constraining very-high-energy and optical emission from FRB 121102 with the MAGIC telescopesFast 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 atMAGIC Collaboration et al.
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122018 -
Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical stateAims: The very high energy (VHE ≳100 GeV) γ-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 anMAGIC Collaboration et al.
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92018 -
The Blazar TXS 0506+056 Associated with a High-energy Neutrino: Insights into Extragalactic Jets and Cosmic-Ray AccelerationA neutrino with energy ˜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 ˜3σ level. We monitored the object in the very-high-energy (VHE) band with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for ˜41 hrAnsoldi, S. et al.
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82018 -
The broad-band properties of the intermediate synchrotron peaked BL Lac S2 0109+22 from radio to VHE gamma-raysThe Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes observed S2 0109+22 in 2015 July during its flaring activity in high-energy gamma-rays observed by Fermi-Large Area Telescope. We analyse the MAGIC data to characterize the very high energy (VHE) gamma-ray emission of S2 0109+22, which belongs to the subclass of intermediateMAGIC Collaboration et al.
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102018 -
The host galaxy of the γ-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (≥108 M⊙) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending toD'Ammando, F. et al.
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72018
