Person:
Nievas Rosillo, Mireia

First Name

Mireia

Last Name

Nievas Rosillo

URI

https://hdl.handle.net/20.500.14352/86790

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Estructura de la Materia, Física Térmica y Electrónica

Identifiers

Full item page

Search Results

Now showing 1 - 10 of 43

First multi-wavelength campaign on the gamma-ray-loud active galaxy IC 310
(Astronomy & astrophysics, 2017) Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Fonseca González, Mª Victoria; López Moya, Marcos; Nievas Rosillo, Mireia
Context. The extragalactic very-high-energy gamma-ray sky is rich in blazars. These are jetted active galactic nuclei that are viewed at a small angle to the line-of-sight. Only a handful of objects viewed at a larger angle are so far known to emit above 100 GeV. Multi-wavelength studies of such objects up to the highest energies provide new insights into the particle and radiation processes of active galactic nuclei. Aims. We aim to report the results from the first multi-wavelength campaign observing the TeV detected nucleus of the active galaxy IC 310, whose jet is observed at a moderate viewing angle of 10 degrees-20 degrees. Methods. The multi-instrument campaign was conducted between 2012 November and 2013 January, and involved observations with MAGIC, Fermi, INTEGRAL, Swift, OVRO, MOJAVE and EVN. These observations were complemented with archival data from the AllWISE and 2MASS catalogs. A one-zone synchrotron self-Compton model was applied to describe the broadband spectral energy distribution. Results. IC 310 showed an extraordinary TeV flare at the beginning of the campaign, followed by a low, but still detectable TeV flux. Compared to previous measurements in this energy range, the spectral shape was found to be steeper during the low emission state. Simultaneous observations in the soft X-ray band showed an enhanced energy flux state and a harder-when-brighter spectral shape behavior. No strong correlated flux variability was found in other frequency regimes. The broad-band spectral energy distribution obtained from these observations supports the hypothesis of a double-hump structure. Conclusions. The harder-when-brighter trend in the X-ray and VHE emission, observed for the first time during this campaign, is consistent with the behavior expected from a synchrotron self-Compton scenario. The contemporaneous broadband spectral energy distribution is well described with a one-zone synchrotron self-Compton model using parameters that are comparable to those found for other gamma-ray-emitting misaligned blazars.
MAGIC detection of very high energy gamma-ray emission from the low-luminosity blazar 1ES 1741+196
(Monthly notices of the Royal Astronomical Society, 2017) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez, A.; Fidalgo, D.; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia
We present the first detection of the nearby (z=0.084) low-luminosity BL Lac object 1ES 1741+196 in the very high energy (VHE: E>100 GeV) band. This object lies in a triplet of interacting galaxies. Early predictions had suggested 1ES 1741+196 to be, along with several other high-frequency BL Lac sources, within the reach of MAGIC detectability. Its detection by MAGIC, later confirmed by VERITAS, helps to expand the small population of known TeV BL Lacs. The source was observed with the MAGIC telescopes between 2010 April and 2011 May, collecting 46 h of good quality data. These observations led to the detection of the source at 6.0 σ confidence level, with a steady flux F(> 100 GeV) = (6.4 ± 1.7_(stat) ± 2.6_(syst)) • 10^(−12) ph cm^(−2) s^( −1) and a differential spectral photon index Γ = 2.4 ± 0.2_(stat) ± 0.2_(syst) in the range of ∼80 GeV - 3 TeV. To study the broad-band spectral energy distribution (SED) simultaneous with MAGIC observations, we use KVA, Swift/UVOT and XRT, and Fermi/LAT data. One-zone synchrotron-self-Compton (SSC) modeling of the SED of 1ES 1741+196 suggests values for the SSC parameters that are quite common among known TeV BL Lacs except for a relatively low Doppler factor and slope of electron energy distribution. A thermal feature seen in the SED is well matched by a giant elliptical’s template. This appears to be the signature of thermal emission from the host galaxy, which is clearly resolved in optical observations.
Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A
(Science, 2018) Domínguez Díaz, Alberto; Barrio Uña, Juan Abel; Contreras González, José Luis; Fonseca González, María Victoria; López Moya, Marcos; Nievas Rosillo, Mireia; Fidalgo, David; Sivakoff, Gregory; American Association for the Advancement of Science
Neutrino emission from a flaring blazar Neutrinos interact only very weakly with matter, but giant detectors have succeeded in detecting small numbers of astrophysical neutrinos. Aside from a diffuse background, only two individual sources have been identified: the Sun and a nearby supernova in 1987. A multiteam collaboration detected a high-energy neutrino event whose arrival direction was consistent with a known blazar—a type of quasar with a relativistic jet oriented directly along our line of sight. The blazar, TXS 0506+056, was found to be undergoing a gamma-ray flare, prompting an extensive multiwavelength campaign. Motivated by this discovery, the IceCube collaboration examined lower-energy neutrinos detected over the previous several years, finding an excess emission at the location of the blazar. Thus, blazars are a source of astrophysical neutrinos.
Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
(Astronomy & astrophysics, 2017) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Domínguez, A.; Fidalgo, D.; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia
Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the γ-ray range from 0.1 GeV to 20 TeV, RXTE and Swift to cover wavelengths from UV to hard X-rays, and GASP-WEBT that provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St.Petersburg observatories. We evaluate the variability of the source and interband correlations, the γ-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Methods. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands, where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the “single-curve SSC model adjustment” typically reported in the literature. Results. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two-independent-zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very high energy (> 100 GeV, VHE) γ-rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE γ-rays). Conclusions. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month long observing campaign in 2009, the highest-energy (and most variable) electrons that are responsible for the VHE γ-rays do not make a dominant contribution to the ∼1 keV emission. Alternatively, there could be a very variable component contributing to the VHE γ-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed γ-ray flaring activity, with the EVPA rotation coincident with the first γ-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties.
Prospects for Cherenkov Telescope Array observations of the young supernova remnant RX J1713.7-3946
(Astrophysical journal, 2017) Arqueros Martínez, Fernando; Barrio Uña, Juan Abel; Contreras González, José Luis; Franco Peláez, Francisco Javier; López Moya, Marcos; Mirabal Barrios, Néstor; Nievas Rosillo, Mireia; Rosado Vélez, Jaime; Tejedor Álvarez, Luis Ángel
We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7−3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti)correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7−3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.
Gamma-ray flaring activity of NGC 1275 in 2016-2017 measured by MAGIC
(Astronomy & astrophysics, 2018) 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, Lab; otros, ...
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 in the eventuality of an enhancement of the magnetic field threading the hole from its equipartition value with the gas pressure in the accretion flow. The observed gamma-ray flare therefore challenges all the discussed models for fast variability of VHE gamma-ray emission in active galactic nuclei.
Very-high-energy gamma-ray observations of the Type Ia Supernova SN 2014J with the MAGIC telescopes
(Astronomy & astrophysics, 2017) Antoranz Canales, Pedro; Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Domínguez, A.; Fidalgo, D.; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia
Context. In this work we present data from observations with the MAGIC telescopes of SN 2014J detected in January 21 2014, the closest Type Ia supernova since Imaging Air Cherenkov Telescopes started to operate. Aims. We probe the possibility of very-high-energy (VHE; E ≥ 100 GeV) gamma rays produced in the early stages of Type Ia supernova explosions. Methods. We performed follow-up observations after this supernova explosion for 5 days, between January 27 and February 2 in 2014. We search for gamma-ray signal in the energy range between 100 GeV and several TeV from the location of SN 2014J using data from a total of ∼ 5.5 hours of observations. Prospects for observing gamma-rays of hadronic origin from SN 2014J in the near future are also being addressed. Results. No significant excess was detected from the direction of SN 2014J. Upper limits at 95% confidence level on the integral flux, assuming a power-law spectrum, dF/dE ∝ E −Γ , with a spectral index of Γ = 2.6, for energies higher than 300 GeV and 700 GeV, are established at 1.3 × 10−12 and 4.1 × 10−13 photons cm−2 s −1 , respectively. Conclusions. For the first time, upper limits on the VHE emission of a Type Ia supernova are established. The energy fraction isotropically emitted into TeV gamma rays during the first ∼ 10 days after the supernova explosion for energies greater than 300 GeV is limited to 10−6 of the total available energy budget (∼ 1051 erg). Within the assumed theoretical scenario, the MAGIC upper limits on the VHE emission suggest that SN 2014J will not be detectable in the future by any current or planned generation of Imaging Atmospheric Cherenkov Telescopes.
Constraining very-high-energy and optical emission from FRB 121102 with the MAGIC telescopes
(Monthly notices of the royal astronomical society, 2018) 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.
A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
(Monthly notices of the royal astronomical society, 2017) Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Domínguez-Adame Acosta, Francisco; Fidalgo, David Friedrich Carreto; Fonseca González, Mª Victoria; López Moya, Marcos; Nievas Rosillo, Mireia
It is widely believed that the bulk of the Galactic cosmic rays are accelerated in supernova remnants (SNRs). However, no observational evidence of the presence of particles of PeV energies in SNRs has yet been found. The young historical SNR Cassiopeia A (Cas A) appears as one of the best candidates to study acceleration processes. Between December 2014 and October 2016 we observed Cas A with the MAGIC telescopes, accumulating 158 hours of good-quality data. We derived the spectrum of the source from 100 GeV to 10 TeV. We also analysed ∼8 years of F ermiLAT to obtain the spectral shape between 60 MeV and 500 GeV. The spectra measured by the LAT and MAGIC telescopes are compatible within the errors and show a clear turn off (4.6 σ) at the highest energies, which can be described with an exponential cut-off at Ec = 3.5(₋₁‚₀⁺¹’⁶ )_(stat) (⁺⁰’⁸ ₋‚₀₉)_(sys) TeV. The gamma-ray emission from 60 MeV to 10 TeV can be attributed to a population of high-energy protons with spectral index ∼2.2 and energy cut-off at ∼10 TeV. This result indicates that Cas A is not contributing to the high energy (∼PeV) cosmic-ray sea in a significant manner at the present moment. A one-zone leptonic model fails to reproduce by itself the multiwavelength spectral energy distribution. Besides, if a non-negligible fraction of the flux seen by MAGIC is produced by leptons, the radiation should be emitted in a region with a low magnetic field (B<≈100µG) like in the reverse shock.
Multiwavelength observations of a VHE gamma-ray flare from PKS 1510–089 in 2015
(Astronomy & astrophysics, 2017) Barrio Uña, Juan Abel; Bonnefoy, Simon Francois Albert; Contreras González, José Luis; Domínguez-Adame Acosta, Francisco; Fidalgo, David Friedrich Carreto; Fonseca González, Mª Victoria; López Moya, Marcos; Nievas Rosillo, Mireia
Context. PKS 1510 089 is one of only a few flat spectrum radio quasars detected in the VHE (very-high-energy, > 100 GeV) gamma-ray band. Aims. We study the broadband spectral and temporal properties of the PKS 1510 089 emission during a high gamma-ray state. Methods. We performed VHE gamma-ray observations of PKS 1510-089 with the MAGIC telescopes during a long, high gamma-ray state in May 2015. In order to perform broadband modeling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray, and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state. Results. PKS 1510-089 was detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, due to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to the ones obtained during previous measurements of the source. The observed flux variability sets for the first time constraints for the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.