scholarly journals Simulations of Gamma-Ray Emission from Magnetized Microquasar Jets

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Odysseas Kosmas ◽  
Theodoros Smponias
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Stellar System ◽  
Compact Object ◽  
High Energy ◽  
Radiative Properties ◽  
Flow Density ◽  
Hadronic Jets ◽  
X Ray ◽  
Jet Plasma

In this work, we simulate γ-rays created in the hadronic jets of the compact object in binary stellar systems known as microquasars. We utilize as the main computational tool the 3D relativistic magnetohydrodynamical code PLUTO combined with in-house derived codes. Our simulated experiments refer to the SS433 X-ray binary, a stellar system in which hadronic jets have been observed. We examine two new model configurations that employ hadron-based emission mechanisms. The simulations aim to explore the dependence of the γ-ray emissions on the dynamical as well as the radiative properties of the jet (hydrodynamic parameters of the mass-flow density, gas-pressure, temperature of the ejected matter, high energy proton population inside the jet plasma, etc.). The results of the two new scenarios of initial conditions for the microquasar stellar system studied are compared to those of previously considered scenarios.

scholarly journals Tidal tearing of circumstellar disks in Be/X-ray and gamma-ray binaries

2016 ◽  
Vol 12 (S329) ◽  
pp. 432-432
Author(s):  
Atsuo T. Okazaki
Keyword(s):  
Gamma Ray ◽  
Compact Object ◽  
High Energy ◽  
High Mass ◽  
List Type ◽  
X Ray ◽  
Short Period ◽  
Be Star ◽  
X Ray Binaries

AbstractAbout one half of high-mass X-ray binaries host a Be star [an OB star with a viscous decretion (slowly outflowing) disk]. These Be/X-ray binaries exhibit two types of X-ray outbursts (Stella et al. 1986), normal X-ray outbursts (LX~1036−37 erg s−1) and occasional giant X-ray outbursts (LX > 1037 erg s−1). The origin of giant X-ray outbursts is unknown. On the other hand, a half of gamma-ray binaries have a Be star as the optical counterpart. One of these systems [LS I +61 303 (Porb = 26.5 d)] shows the superorbital (1,667 d) modulation in radio through X-ray bands. No consensus has been obtained for its origin. In this paper, we study a possibility that both phenomena are caused by a long-term, cyclic evolution of a highly misaligned Be disk under the influence of a compact object, by performing 3D hydrodynamic simulations. We find that the Be disk cyclically evolves in mildly eccentric, short-period systems. Each cycle consists of the following stages: 1)As the Be disk grows with time, the initially circular disk becomes eccentric by the Kozai-Lidov mechanism.2)At some point, the disk is tidally torn off near the base and starts precession.3)Due to precession, a gap opens between the disk base and mass ejection region, which allows the formation of a new disk in the stellar equatorial plane (see Figure 1).4)The newly formed disk finally replaces the precessing old disk. Such a cyclic disk evolution has interesting implications for the long-term behavior of high energy emission in Be/X-ray and gamma-ray binaries.

scholarly journals Multiband nonthermal radiative properties of pulsar wind nebulae

2018 ◽  
Vol 609 ◽  
pp. A110 ◽  
Author(s):  
Bo-Tao Zhu ◽  
Li Zhang ◽  
Jun Fang
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
High Energy ◽  
Maximum Energy ◽  
Energy Electron ◽  
Radiative Properties ◽  
Spectral Energy ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Pulsar Wind

Aims. The nonthermal radiative properties of 18 pulsar wind nebulae (PWNe) are studied in the 1D leptonic model. Methods. The dynamical and radiative evolution of a PWN in a nonradiative supernova remnant are self-consistently investigated in this model. The leptons (electrons/positrons) are injected with a broken power-law form, and nonthermal emission from a PWN is mainly produced by time-dependent relativistic leptons through synchrotron radiation and inverse Compton process. Results. Observed spectral energy distributions (SEDs) of all 18 PWNe are reproduced well, where the indexes of low-energy electron components lie in the range of 1.0–1.8 and those of high-energy electron components in the range of 2.1–3.1. Our results show that FX/Fγ > 10 for young PWNe; 1 <FX/Fγ ≤ 10 for evolved PWNe, except for G292.0+1.8; and FX/Fγ ≤ 1 for mature/old PWNe, except for CTA 1. Moreover, most PWNe are particle-dominated. Statistical analysis for the sample of 14 PWNe further indicate that (1) not all pulsar parameters have correlations with electron injection parameters, but electron maximum energy and PWN magnetic field correlate with the magnetic field at the light cylinder, the potential difference at the polar cap, and the spin-down power; (2) the spin-down power positively correlates with radio, X-ray, bolometric, and synchrotron luminosities, but does not correlate with gamma-ray luminosity; (3) the spin-down power positively correlates with radio, X-ray, and γ-band surface brightness; and (4) the PWN radius and the PWN age negatively correlate with X-ray luminosity, the ratio of X-ray to gamma-ray luminosities, and the synchrotron luminosity.

scholarly journals Comptonization as Blazar High Energy Emission

1996 ◽  
Vol 175 ◽  
pp. 421-422 ◽  
Author(s):  
Oliver Dreissigacker
Keyword(s):  
Particle Acceleration ◽  
Gamma Ray ◽  
High Energy ◽  
Energy Output ◽  
Relativistic Electrons ◽  
X Ray ◽  
Γ Ray ◽  
Exotic Particle ◽  
Jet Plasma ◽  
High Energy Emission

We explain the overall continuous Grazar (Gamma Ray Blazar) spectrum from the synchrotron turnover to the EGRET GeV detections by means of Comptonization in the parsec scale jet's substructures.While making use of the constraints on the synchrotron spectrum and other measurable quantities, no exotic particle acceleration is needed to achieve the high energy output.We show, that the “Lighthouse Model” of blobs of relativistic electrons, travelling with the jet plasma at relativistic speeds, produce both, correct timescales and shapes for the lightcurve, and correct ratios and slopes of the synchrotron, X-ray and γ-ray branches.

scholarly journals Gamma-Ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 36
Author(s):  
Yoshiyuki Inoue ◽  
Dmitry Khangulyan ◽  
Akihiro Doi
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Thermal Activity ◽  
X Ray ◽  
Cascade Models ◽  
Coronal Activity ◽  
Ngc 1068 ◽  
High Energy Particles

To explain the X-ray spectra of active galactic nuclei (AGN), non-thermal activity in AGN coronae such as pair cascade models has been extensively discussed in the past literature. Although X-ray and gamma-ray observations in the 1990s disfavored such pair cascade models, recent millimeter-wave observations of nearby Seyferts have established the existence of weak non-thermal coronal activity. In addition, the IceCube collaboration reported NGC 1068, a nearby Seyfert, as the hottest spot in their 10 yr survey. These pieces of evidence are enough to investigate the non-thermal perspective of AGN coronae in depth again. This article summarizes our current observational understanding of AGN coronae and describes how AGN coronae generate high-energy particles. We also provide ways to test the AGN corona model with radio, X-ray, MeV gamma ray, and high-energy neutrino observations.

scholarly journals Fermi-LAT and WMAP observations of the supernova remnant Puppis A

2013 ◽  
Vol 9 (S296) ◽  
pp. 295-299
Author(s):  
Marie-Hélène Grondin ◽  
John W. Hewitt ◽  
Marianne Lemoine-Goumard ◽  
Thierry Reposeur ◽  
Keyword(s):  
Supernova Remnants ◽  
Supernova Remnant ◽  
Gamma Ray ◽  
High Energy ◽  
Radio Spectrum ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Large Area ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Γ Ray

AbstractThe supernova remnant (SNR) Puppis A (aka G260.4-3.4) is a middle-aged supernova remnant, which displays increasing X-ray surface brightness from West to East corresponding to an increasing density of the ambient interstellar medium at the Eastern and Northern shell. The dense IR photon field and the high ambient density around the remnant make it an ideal case to study in γ-rays. Gamma-ray studies based on three years of observations with the Large Area Telescope (LAT) aboard Fermi have revealed the high energy gamma-ray emission from SNR Puppis A. The γ-ray emission from the remnant is spatially extended, and nicely matches the radio and X-ray morphologies. Its γ-ray spectrum is well described by a simple power law with an index of ~2.1, and it is among the faintest supernova remnants yet detected at GeV energies. To constrain the relativistic electron population, seven years of Wilkinson Microwave Anisotropy Probe (WMAP) data were also analyzed, and enabled to extend the radio spectrum up to 93 GHz. The results obtained in the radio and γ-ray domains are described in detail, as well as the possible origins of the high energy γ-ray emission (Bremsstrahlung, Inverse Compton scattering by electrons or decay of neutral pions produced by proton interactions).

scholarly journals The Nature of the Compact Object in the Hard X-Ray Source 4U2206+54

2004 ◽  
Vol 194 ◽  
pp. 208-208
Author(s):  
J. M. Torrejón ◽  
I. Kreykenbohni ◽  
A. Orr ◽  
L. Titarchuk ◽  
I. Negueruela
Keyword(s):  
Neutron Star ◽  
Accretion Disk ◽  
Compact Object ◽  
High Energy ◽  
Energy Data ◽  
X Ray ◽  
Hot Plasma ◽  
Cyclotron Line ◽  
First Time

We present an analysis of archival RXTE and BeppoSAX data of the X-ray source 4U2206+54. For the first time, high energy data (≥ 30 keV) is analyzed. The data is well described by comptonization models in which seed photons with temperatures between 1.1 keV arid 1.5 keV are comptonized by a hot plasma at 50 keV thereby producing a hard tail which extends up to 100 keV. From luminosity arguments it is shown that the area of the soft photons source must be small (r ≈ 1 km) and that the presence of an accretion disk in this system is unlikely. Here we report on the possible existence of a cyclotron line around 30 keV . The presence of a neutron star in the system is strongly favored by the available data.

scholarly journals Imaging in Hard X-ray Astronomy

2003 ◽  
Vol 214 ◽  
pp. 70-83 ◽  
Author(s):  
T. P. Li
Keyword(s):  
Gamma Ray ◽  
Signal To Noise Ratio ◽  
High Energy ◽  
High Signal ◽  
Wide Field ◽  
X Rays ◽  
X Ray ◽  
Energy Gamma ◽  
High Resolution Images ◽  
Energy Processes

The energy range of hard X-rays is a key waveband to the study of high energy processes in celestial objects, but still remains poorly explored. In contrast to direct imaging methods used in the low energy X-ray and high energy gamma-ray bands, currently imaging in the hard X-ray band is mainly achieved through various modulation techniques. A new inversion technique, the direct demodulation method, has been developed since early 90s. with this technique, wide field and high resolution images can be derived from scanning data of a simple collimated detector. The feasibility of this technique has been confirmed by experiment, balloon-borne observation and analyzing simulated and real astronomical data. Based the development of methodology and instrumentation, a high energy astrophysics mission – Hard X-ray Modulation Telescope (HXMT) has been proposed and selected in China for a four-year Phase-A study. The main scientific objectives are a full-sky hard X-ray (20–200 keV) imaging survey and high signal-to-noise ratio timing studies of high energy sources.

scholarly journals Mergers of equal-mass binaries with compact object companions from mass transfer in triple star systems

2020 ◽  
Vol 496 (2) ◽  
pp. 1819-1833
Author(s):  
Nathan W C Leigh ◽  
Silvia Toonen ◽  
Simon F Portegies Zwart ◽  
Rosalba Perna
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Compact Object ◽  
Supernova Explosion ◽  
Equal Mass ◽  
Initial Population ◽  
Triple Systems ◽  
Blue Stragglers ◽  
Orbital Periods ◽  
Binary Evolution

ABSTRACT In this paper, we consider triple systems composed of main-sequence (MS) stars, and their internal evolution due to stellar and binary evolution. Our focus is on triples that produce white dwarfs (WDs), where Roche lobe overflow of an evolving tertiary triggers accretion on to the inner binary via a circumbinary disc (CBD) driving it towards a mass ratio of unity. We present a combination of analytic- and population synthesis-based calculations performed using the SeBa code to constrain the expected frequency of such systems, given a realistic initial population of MS triples, and provide the predicted distributions of orbital periods. We identify the parameter space for triples that can accommodate a CBD, to inform future numerical simulations of suitable initial conditions. We find that ≳10 per cent of all MS triples should be able to accommodate a CBD around the inner binary, and compute lower limits for the production rates. This scenario broadly predicts mergers of near equal-mass binaries, producing blue stragglers (BSs), Type Ia supernovae, gamma-ray bursts and gravitational wave-induced mergers, along with the presence of an outer WD tertiary companion. We compare our predicted distributions to a sample of field BS binaries, and argue that our proposed mechanism explains the observed range of orbital periods. Finally, the mechanism considered here could produce hypervelocity MS stars, WDs, and even millisecond pulsars with masses close to the Chandrasekhar mass limit, and be used to constrain the maximum remnant masses at the time of any supernova explosion.

scholarly journals Gamma-Ray Pulsar Emission Models

1996 ◽  
Vol 160 ◽  
pp. 315-322 ◽  
Author(s):  
Alice K. Harding
Keyword(s):  
Spectral Index ◽  
Gamma Ray ◽  
High Energy ◽  
Pulsar Emission ◽  
High Energy Radiation ◽  
X Ray ◽  
Gamma Ray Detectors ◽  
Emerging Patterns ◽  
Increased Sensitivity ◽  
Emission Models

AbstractWith the increased sensitivity of gamma-ray detectors on the Compton Gamma-Ray Observatory (CGRO) the number of presently known gamma-ray pulsars has grown. The new detections are beginning to provide clues to the origin of the high-energy radiation in the form of emerging patterns and correlations among observed quantities such as gamma-ray efficiency and spectral index vs. age. But there are still many questions about the location of the emission and its relation to the radio, optical and X-ray pulses. This paper will review models for gamma-ray emission from pulsars and will examine how well the detailed predictions of these models account for the existing observations.

scholarly journals Time-Domain Astronomy with Swift, Fermi and Lobster

2011 ◽  
Vol 7 (S285) ◽  
pp. 41-46 ◽  
Author(s):  
Neil Gehrels ◽  
Scott D. Barthelmy ◽  
John K. Cannizzo
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Tidal Disruption ◽  
X Ray ◽  
Order Of Magnitude ◽  
New Type ◽  
The Crab Nebula ◽  
High Energy Emission ◽  
Higher Sensitivity

AbstractThe dynamic transient gamma-ray sky is revealing many interesting results, largely due to findings by Fermi and Swift. The list includes new twists on gamma-ray bursts (GRBs), a GeV flare from a symbiotic star, GeV flares from the Crab Nebula, high-energy emission from novae and supernovae, and, within the last year, a new type of object discovered by Swift—a jetted tidal disruption event. In this review we present highlights of these exciting discoveries. A new mission concept called Lobster is also described; it would monitor the X-ray sky at order-of-magnitude higher sensitivity than current missions can.

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