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Search Results: 1 - 10 of 172 matches for " Nissim Fraija "
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GeV - PeV Neutrino Production and Oscillation in hidden jets from GRBs
Nissim Fraija
Physics , 2013, DOI: 10.1093/mnras/stt2036
Abstract: Long gamma-ray bursts have been widely associated with collapsing massive stars in the framework of collapsar model. High-energy neutrinos and photons can be produced in the internal shocks of middle relativistic jets from core-collapse supernova. Although photons can hardly escape, high-energy neutrinos could be the only signature when the jets are hidden. We show that using suitable parameters, high-energy neutrinos in GeV - PeV range can be produced in the hidden jet inside the collapsar, thus demonstrating that these objects are candidates to produce neutrinos with energies between 1 - 10 PeV which were observed with IceCube. On the other hand, due to matter effects, high-energy neutrinos may oscillate resonantly from one flavor to another before leaving the star. Using two (solar, atmospheric and accelerator parameters) and three neutrino mixing, we study the possibility of resonant oscillation for these neutrinos created in internal shocks. Also we compute the probabilities of neutrino oscillations in the matter at different distances along the jet (before leaving the star) and after in vacuum, on their path to Earth. Finally, neutrino flavor ratios on Earth are estimated.
Could a plasma in quasi-thermal equilibrium be associated to the "orphan" TeV flares ?
Nissim Fraija
Physics , 2015, DOI: 10.1016/j.astropartphys.2015.04.007
Abstract: TeV $\gamma$-ray detections in flaring states without activity in X-rays from blazars have attracted much attention due to the irregularity of these "orphan" flares. Although the synchrotron self-Compton model has been very successful in explaining the spectral energy distribution and spectral variability of these sources, it has not been able to describe these atypical flaring events. On the other hand, an electron-positron pair plasma at the base of the AGN jet was proposed as the mechanism of bulk acceleration of relativistic outflows. This plasma in quasi-themal equilibrium called Wein fireball emits radiation at MeV-peak energies serving as target of accelerated protons. In this work we describe the "orphan" TeV flares presented in blazars 1ES 1959+650 and Mrk421 assuming geometrical considerations in the jet and evoking the interactions of Fermi-accelerated protons and MeV-peak target photons coming from the Wein fireball. After describing successfully these "orphan" TeV flares, we correlate the TeV $\gamma$-ray, neutrino and UHECR fluxes through p$\gamma$ interactions and calculate the number of high-energy neutrinos and UHECRs expected in IceCube/AMANDA and TA experiment, respectively. In addition, thermal MeV neutrinos produced mainly through electron-positron annihilation at the Wein fireball will be able to propagate through it. By considering two- (solar, atmospheric and accelerator parameters) and three-neutrino mixing, we study the resonant oscillations and estimate the neutrino flavor ratios as well as the number of thermal neutrinos expected on Earth.
GRB 110731A: Early afterglow in stellar wind powered by a magnetized outflow
Nissim Fraija
Physics , 2015, DOI: 10.1088/0004-637X/804/2/105
Abstract: One of the most energetic gamma-ray burst GRB 110731A was observed from optical to GeV energy range. Previous analysis on the prompt phase revealed similarities with the Large Area Telescope (LAT) bursts observed by Fermi: i) a delayed onset of the high-energy emission ($> 100$ MeV), ii) a short-lasting bright peak at later times and iii) a temporally extended component from this phase and lasting hundreds of seconds. Additionally to the prompt phase, multiwavelength observations over different epochs showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind of its progenitor. We apply this model to interpret the temporally extended LAT emission and the brightest LAT peak exhibited by the prompt phase of GRB 110731A. Additionally, using the same set of parameters, we describe the multiwavelength afterglow observations. The origin of the temporally extended LAT, X-ray and optical flux is explained through synchrotron radiation from the forward shock and the brightest LAT peak is described evoking the synchrotron self-Compton emission from the reverse shock. The bulk Lorentz factor required in this model ($\Gamma\simeq520$) lies in the range of values demanded for most LAT-detected gamma-ray bursts. We show that the strength of the magnetic field in the reverse-shock region is $\sim$ 50 times stronger than in the forward-shock region. This result suggests that for GRB 110731A, the central engine is likely entrained with strong magnetic fields.
Propagation and neutrino oscillations in the base of a highly magnetized gamma-ray burst fireball flow
Nissim Fraija
Physics , 2014, DOI: 10.1088/0004-637X/787/2/140
Abstract: Neutrons play an important role in the dynamics of gamma-ray bursts. The presence of neutrons in the baryon-loaded fireball is expected. If the neutrons abundance is comparable to that of protons, important features may be observed such as quasi-thermal multi-GeV neutrinos in coincidence with a subphotospheric $\gamma$-ray emission, nucleosynthesis at later times and rebrightening of the afterglow emission. Additionally, thermal MeV neutrinos are created by electron-positron annihilation, electron (positron) capture on protons (neutrons) and nucleonic bremsstrahlung. Although MeV neutrinos are difficult to detect, quasi-thermal GeV neutrinos are expected in km$^3$ detectors and/or DeepCore+IceCube. In this paper, we show that neutrino oscillations have outstanding implications for the dynamics of the fireball evolution and also that they can be detected through their flavor ratio on Earth. For that we derive the resonance and charged-neutrality conditions as well as the neutrino self-energy and effective potential up to order $m_W^{-4}$ at strong, moderate and weak magnetic field approximation to constrain the dynamics of the fireball. We found important implications: i) resonant oscillations are suppressed for high baryon densities as well as neutrons abundance larger than that of protons and ii) the effect of magnetic field is to decrease the proton-to-neutron ratio aside from the number of multi-GeV neutrinos expected in DeepCore detector. Also we estimate the GeV neutrino flavor ratios along the jet and on Earth.
Gamma-ray fluxes from the core emission of Centaurus A: A puzzle solved
Nissim Fraija
Physics , 2014, DOI: 10.1093/mnras/stu652
Abstract: A high-energy component in the radio galaxy Centaurus A was reported after analyzing four years of Fermi data. The spectrum of this component is described by means of a broken power law with a break energy of 4 GeV and, below and above spectral indices of $\alpha_1$=2.74$\pm$0.03 and $\alpha_2$=2.09$\pm$0.20, respectively. Also a faint $\gamma$-ray flux at TeV energies was detected by H.E.S.S.. In this paper we show that the spectrum at GeV-TeV energies is described through synchrotron self-Compton emission up to a few GeV ($\sim$ 4 GeV) and $\pi^0$ decay products up to TeV energies, although the emission of synchrotron radiation by muons could contribute to the spectrum at GeV energies, if they are rapidly accelerated. Muons and $\pi^0$s are generated in the interactions of accelerated protons with two populations of seed photons which were reported by Compton Gamma-Ray Observatory: one population at intermediate state emission with energy peak of 0.15 MeV and another at low state emission with energy peak of 0.59 MeV. In addition, we show that the reported observations of ultra-high-energy cosmic rays and non high-energy neutrino detection around Centaurus A can be explained through these interactions, assuming that proton spectrum is extended up to ultra-high-energies.
Resonant oscillations of GeV - TeV neutrinos in internal shocks from gamma-ray burst jets inside the stars
Nissim Fraija
Physics , 2015, DOI: 10.1093/mnras/stv737
Abstract: High-energy neutrinos generated in collimated jets inside the progenitors of gamma-ray bursts (GRBs) have been related with the events detected by IceCube. These neutrinos, produced by hadronic interactions of Fermi-accelerated protons with thermal photons and hadrons in internal shocks, are the only signature when jet has not broken out or failed. Taking into account that the photon field is thermalized at keV energies and the standard assumption that the magnetic field maintains a steady value throughout the shock region (with a width of $10^{10} - 10^{11}$ cm in the observed frame), we study the effect of thermal and magnetized plasma generated in internal shocks on the neutrino oscillations. We calculate the neutrino effective potential generated by this plasma, the effects of the envelope of the star, and the vacuum on the path to Earth. By considering these three effects, the two (solar, atmospheric and accelerator parameters) and three neutrino mixing, we show that although GeV - TeV neutrinos can oscillate resonantly from one flavor to another, a nonsignificant deviation of the standard flavor ratio (1:1:1) could be expected on Earth.
Correlation of $γ$-ray and high-energy cosmic ray fluxes from the giant lobes of Centaurus A
Nissim Fraija
Physics , 2013, DOI: 10.1088/0004-637X/783/1/44
Abstract: The spectral energy distribution of giant lobes shows one main peak detected by the Wilkinson Microwave Anisotropy Probe at low energy of $10^{-5}$ eV and a faint $\gamma$-ray flux imaged by Fermi Large Area Telescope at energy $\geq$ 100 MeV. On the other hand, Pierre Auger Observatory associated some ultra-high-energy cosmic rays with the direction of Centaurus A and IceCube reported 28 neutrino-induced events in a TeV - PeV energy range, although none of them related with this direction. In this work we describe the spectra for each of the lobes, the main peak with synchrotron radiation, and the high-energy emission with $pp$ interactions. Obtaining a good description of the main peak, we deduce the magnetic fields, electron densities and the age of the lobes. Describing successfully the $\gamma$-ray emission by pp interactions and considering as targets those thermal particles in the lobes with density in the range $10^{-10}$ to $10^{-4}\, {\rm cm}^{-3}$, we calculate the number of ultra-high-energy cosmic rays. Although $\gamma$-spectrum is well described with any density in the range, only when $10^{-4}\, {\rm cm}^{-3}$ is considered, the expected number of events is very similar to that observed by Pierre Auger Observatory, otherwise we obtain an excessive luminosity. In addition, correlating the $\gamma$-ray and neutrino fluxes through pp interactions we calculate the number of high-energy neutrinos expected in IceCube. Our analysis indicates that neutrinos above 1 TeV cannot be produced in the lobes of Centaurus A, which is consistent with the results recently published by IceCube Collaboration.
Could a multi-PeV neutrino event have as origin the internal shocks inside the GRB progenitor star?
Nissim Fraija
Physics , 2015,
Abstract: The IceCube Collaboration initially reported the detection of 37 extraterrestrial neutrinos in the TeV - PeV energy range. The reconstructed neutrino events were obtained during three consecutive years of data taking, from 2010 to 2013. Although these events have been discussed to have an extragalactic origin, they have not correlated to any known source. Recently, the IceCube Collaboration reported a neutrino-induced muon event with energy of $2.6\pm0.3$ PeV which corresponds to the highest event ever detected. Neither the reconstructed direction of this event (J2000.0), detected on June 11 2014 at R.A.=110$^\circ$.34, Dec.=11$^\circ$.48 matches with any familiar source. Long gamma-ray bursts (lGRBs) are usually associated with the core collapse of massive stars leading a relativistic-collimated jets inside the star with high-energy neutrino production. These neutrinos have been linked to the 37 events previously detected by IceCube detector. In this work, we explore the conditions so that the highest neutrino recently detected could be generated by proton-photon and proton-hadron interactions in internal shocks inside GRB progenitor star and then be detected in IceCube detector. We found that not only low-luminosity but also high-luminosity GRBs could produce this neutrino in progenitors such as Wolf-Rayet and blue super giant stars.
TeV $γ$-ray fluxes from the long campaigns on Mrk421 as constraints on the emission of TeV-PeV Neutrinos and UHECRs
Nissim Fraija,Antonio Marinelli
Physics , 2014, DOI: 10.1016/j.astropartphys.2015.04.005
Abstract: Long TeV $\gamma$-ray campaigns have been carried out to study the spectrum, variability and duty cycle of the BL Lac object Markarian 421. These campaigns have given some evidence of the presence of protons in the jet: i) Its spectral energy distribution which shows two main peaks; one at low energies ($\sim$ 1 keV) and the other at high energies (hundreds of GeV), has been described by using synchrotron proton blazar model. ii) The study of the variability at GeV $\gamma$-rays and X-rays has indicated no significant correlation. iii) TeV $\gamma$-ray detections without activity in X-rays, called "orphan flares" have been observed in this object.\\ Recently, The Telescope Array Collaboration reported the arrival of 72 ultra-high-energy cosmic rays with some of them possibly related to the direction of Markarian 421. The IceCube Collaboration reported the detection of 37 extraterrestrial neutrinos in the TeV - PeV energy range collected during three consecutive years. In particular, no neutrino track events were associated with this source. In this paper, we consider the proton-photon interactions to correlate the TeV $\gamma$-ray fluxes reported by long campaigns with the neutrino and ultra-high-energy cosmic ray observations around this blazar. Considering the results reported by The IceCube and Telescope Array Collaborations, we found that only from $\sim$ 25\% to 70\% of TeV fluxes described with a power law function with exponential cutoff can come from the proton-photon interactions.
Neutrino Oscillation as a constraint in the dynamics of Pop III Gamma Ray Bursts
Nissim Fraija,Enrique Moreno Mendez
Physics , 2014,
Abstract: Population III stars are believed to be rapidly-rotating sources with a mass range of hundreds to thousand of solar masses. Masses larger than 260 M$_\odot$ are expected to collapse resulting in central rotating Kerr black holes with large rotation parameter a. Due to particle-antiparticle asymmetry is small, we use the neutrino effective potential up to order $1/M_W^4$ in a magnetized plasma at the base of the ejecta to constrain the rotation parameter by means of neutrino oscillations. Additionally, we investigate the implications in the magnetic field, temperature and electron asymmetry.
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