scholarly journals Refining the origins of the gamma-ray binary 1FGL J1018.6–5856

2018 ◽  
Vol 619 ◽  
pp. A26 ◽  
Author(s):  
B. Marcote ◽  
M. Ribó ◽  
J. M. Paredes ◽  
M. Y. Mao ◽  
P. G. Edwards
Keyword(s):  
Radio Emission ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Three Dimensional ◽  
Compact Object ◽  
High Energy ◽  
Physical Relation ◽  
Long Baseline ◽  
The Galaxy ◽  
Peculiar Motion

Context. Gamma-ray binaries are systems composed of a massive star and a compact object that exhibit emission from radio to very high energy gamma rays. They are ideal laboratories to study particle acceleration and a variety of physical processes that vary as a function of the orbital phase. Aims. We aim to study the radio emission of the gamma-ray binary 1FGL J1018.6–5856 to constrain the emitting region and determine the peculiar motion of the system within the Galaxy to clarify its origin. Methods. We analyzed an observation of 1FGL J1018.6–5856 with the Australian Long Baseline Array (LBA) at 8.4 GHz to obtain an accurate astrometry of the system and study its emission on milliarcsecond scales. We combined these data with the optical Gaia DR2 and UCAC4 catalogs to consolidate the astrometry information therein. Results. The gamma-ray binary 1FGL J1018.6–5856 shows compact radio emission (< 3 mas or ≲20 au at ∼6.4 kpc distance), implying a brightness temperature of ≳5.6 × 106 K, and confirming its nonthermal origin. We report consistent results between the proper motion reported by Gaia DR2 and the positions obtained from the Gaia DR2, UCAC4, and LBA data (spanning 20 yr in total). We also determined the distance to 1FGL J1018.6–5856 to be 6.4−0.7+1.7. Together with the radial velocity of the source we computed its three-dimensional (3D) proper and peculiar motion within the Galaxy. We obtained a peculiar motion of 1FGL J1018.6–5856 on its regional standard of rest (RSR) frame of |u| = 45−9+30, with the system moving away from the Galactic plane. In the simplest scenario of a symmetric stellar core collapse we estimate a mass loss of 4 ≲ ΔM ≲ 9 M⊙ during the creation of the compact object. Conclusions. 1FGL J1018.6–5856 exhibits compact radio emission similar to that detected in other gamma-ray binaries. We provide the first accurate peculiar motion estimations of the system and place it within the Galaxy. The obtained motion and distance excludes the physical relation of the binary source with the supernova remnant (SNR) G284.3−1.8.

scholarly journals Colliding-Wind Binaries as a Source of TeV Cosmic Rays

2021 ◽  
Vol 8 ◽  
Author(s):  
Grzegorz Kowal ◽  
Diego A. Falceta-Gonçalves
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Strong Shock ◽  
Compact Object ◽  
High Energy ◽  
Test Particles ◽  
Very High Energy ◽  
Magnetohydrodynamic Simulations ◽  
Very High

In addition to gamma-ray binaries which contain a compact object, high-energy and very high–energy gamma rays have also been detected from colliding-wind binaries. The collision of the winds produces two strong shock fronts, one for each wind, both surrounding a shock region of compressed and heated plasma, where particles are accelerated to very high energies. Magnetic field is also amplified in the shocked region on which the acceleration of particles greatly depends. In this work, we performed full three-dimensional magnetohydrodynamic simulations of colliding winds coupled to a code that evolves the kinematics of passive charged test particles subject to the plasma fluctuations. After the run of a large ensemble of test particles with initial thermal distributions, we show that such shocks produce a nonthermal population (nearly 1% of total particles) of few tens of GeVs up to few TeVs, depending on the initial magnetization level of the stellar winds. We were able to determine the loci of fastest acceleration, in the range of MeV/s to GeV/s, to be related to the turbulent plasma with amplified magnetic field of the shock. These results show that colliding-wind binaries are indeed able to produce a significant population of high-energy particles, in relatively short timescales, compared to the dynamical and diffusion timescales.

scholarly journals A UNIFIED MODEL OF HIGH-ENERGY ASTROPHYSICAL PHENOMENA

2005 ◽  
Vol 20 (29) ◽  
pp. 6562-6583 ◽  
Author(s):  
A. DE RÚJULA
Keyword(s):  
Cosmic Rays ◽  
Gamma Ray ◽  
Background Radiation ◽  
Compact Object ◽  
Cosmic Ray ◽  
High Energy ◽  
Unified Model ◽  
Theoretical Understanding ◽  
Total Luminosity ◽  
The Galaxy

I outline a unified model of high-energy astrophysics, in which the gamma background radiation, cluster "cooling flows", gamma-ray bursts, X-ray flashes and cosmic-ray electrons and nuclei of all energies — share a common origin. The mechanism underlying these phenomena is the emission of relativistic "cannonballs" by ordinary supernovae, analogous to the observed ejection of plasmoids by quasars and microquasars. I concentrate on Cosmic Rays: the longest-lasting conundrum in astrophysics. The distribution of Cosmic Rays in the Galaxy, their total "luminosity", the broken power-law spectra with their observed slopes, the position of the knee(s) and ankle(s), and the alleged variations of composition with energy are all explained in terms of simple and "standard" physics. The model is only lacking a satisfactory theoretical understanding of the "cannon" that emits the cannonballs in catastrophic episodes of accretion onto a compact object.

scholarly journals Neutrino Astronomy with IceCube

2016 ◽  
Vol 12 (S324) ◽  
pp. 322-329
Author(s):  
Kevin J. Meagher
Keyword(s):  
Real Time ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Galactic Nuclei ◽  
High Energy ◽  
Glacial Ice ◽  
Astrophysical Neutrinos ◽  
Charged Secondary ◽  
Neutrino Astronomy ◽  
The Antarctic

AbstractThe IceCube Neutrino Observatory is a cubic kilometer neutrino telescope located at the Geographic South Pole. Cherenkov radiation emitted by charged secondary particles from neutrino interactions is observed by IceCube using an array of 5160 photomultiplier tubes embedded between a depth of 1.5 km to 2.5 km in the Antarctic glacial ice. The detection of astrophysical neutrinos is a primary goal of IceCube and has now been realized with the discovery of a diffuse, high-energy flux consisting of neutrino events from tens of TeV up to several PeV. Many analyses have been performed to identify the source of these neutrinos: correlations with active galactic nuclei, gamma-ray bursts, and the galactic plane. IceCube also conducts multi-messenger campaigns to alert other observatories of possible neutrino transients in real-time. However, the source of these neutrinos remains elusive as no corresponding electromagnetic counterparts have been identified. This proceeding will give an overview of the detection principles of IceCube, the properties of the observed astrophysical neutrinos, the search for corresponding sources (including real-time searches), and plans for a next-generation neutrino detector, IceCube–Gen2.

scholarly journals SEARCH FOR NEUTRINO EMISSION FROM GAMMA-RAY SOURCES WITH THE ANTARES TELESCOPE

2012 ◽  
Vol 08 ◽  
pp. 307-310
Author(s):  
C. BIGONGIARI
Keyword(s):  
Gamma Ray ◽  
Neutrino Flux ◽  
Three Dimensional ◽  
Effective Area ◽  
High Energy ◽  
Neutrino Telescope ◽  
Neutrino Detector ◽  
Upper Limits ◽  
Cosmic Neutrino ◽  
Promising Source

ANTARES is the first undersea neutrino detector ever built and presently the neutrino telescope with the largest effective area operating in the Northern Hemisphere. A three-dimensional array of photomultiplier tubes detects the Cherenkov light induced by the muons produced in the interaction of high energy neutrinos with the matter surrounding the detector. The detection of astronomical neutrino sources is one of the main goals of ANTARES. The search for point-like neutrino sources with the ANTARES telescope is described and the preliminary results obtained with data collected from 2007 to 2010 are shown. No cosmic neutrino source has been observed and neutrino flux upper limits have been calculated for the most promising source candidates.

scholarly journals Orbital elements of different Galactic population objects

1993 ◽  
Vol 153 ◽  
pp. 369-370
Author(s):  
L.P. Ossipkov ◽  
S.A. Kutuzov
Keyword(s):  
Galactic Plane ◽  
Three Dimensional ◽  
Meridional Plane ◽  
Orbital Elements ◽  
Classical Analysis ◽  
Significant Difference ◽  
Maximal Height ◽  
The Galaxy ◽  
Numerical Orbit ◽  
Component Models

The study of prevalent orbits in galactic subsystems can help us understand galactic structure and clarify its history. The classical analysis of flat orbits and metallicities of old stars led Eggen et al. (1962) to formulate the rapid collapse of the primordial Galaxy. On the other side Yoshii & Saio (1979) studied three-dimensional orbits that separate in spherical coordinates. They found the Galaxy contracted quasi-stationary after the formation of halo objects. Here we shall briefly discuss the results of numerical orbit calculations (with Merson's method) for selected galactic subsystems. The axially symmetrical two-component model of the Galaxy (Kutuzov, Ossipkov 1989) was adopted. One-component models (Barkhatova et al. 1987, Kutuzov 1988) were used also but no significant difference in orbit elements was found (Kutuzov & Ossipkov 1992). Pericenter and apocenter distances, Rp and Ra, and the maximal height of objects over the galactic plane, zm, were used as orbit elements as well as dimensionless quantities e = (Ra — Rp)/(Ra + Rp) (eccentricity) and c = 2zm/(Ra — Rp) (the flatness of box filled by orbit projection on the meridional plane).

scholarly journals Gamma-ray emission in radio galaxies under the VLBI scope

2019 ◽  
Vol 627 ◽  
pp. A148 ◽  
Author(s):  
R. Angioni ◽  
E. Ros ◽  
M. Kadler ◽  
R. Ojha ◽  
C. Müller ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Monitoring Program ◽  
Radio Galaxies ◽  
High Energy ◽  
Viewing Angle ◽  
Long Baseline ◽  
Superluminal Motion ◽  
Multi Wavelength ◽  
The Individual ◽  
The Relationship

Aims. In the framework of the multi-wavelength and very long baseline interferometry (VLBI) monitoring program TANAMI (Tracking Active Nuclei with Austral Milliarcsecond Interferometry), we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the γ-ray properties of the sources. Our study investigates systematically, for the first time, the relationship between the two energy regimes in radio galaxies. In this first paper, we focus on Fermi-LAT-detected sources. Methods. The TANAMI program monitors a large sample of radio-loud AGN at 8.4 GHz and 22.3 GHz with the Australian long baseline array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. We performed a kinematic analysis for five γ-ray detected radio galaxies using multi-epoch 8.4 GHz VLBI images, deriving limits on intrinsic jet parameters such as speed and viewing angle. We analyzed 103 months of Fermi-LAT data in order to study possible connections between the γ-ray properties and the pc-scale jets of Fermi-LAT-detected radio galaxies, both in terms of variability and average properties. We discuss the individual source results and draw preliminary conclusions on sample properties including published VLBI results from the MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) survey, with a total of fifteen sources. Results. We find that the first γ-ray detection of Pictor A might be associated with the passage of a new VLBI component through the radio core, which appears to be a defining feature of high-energy emitting Fanaroff-Riley type II radio galaxies. We detect subluminal parsec-scale jet motions in the peculiar AGN PKS 0521−36, and we confirm the presence of fast γ-ray variability in the source down to timescales of six hours, which is not accompanied by variations in the VLBI jet. We robustly confirm the presence of significant superluminal motion, up to βapp ∼ 3, in the jet of the TeV radio galaxy PKS 0625−35. Our VLBI results constrain the jet viewing angle to be θ <  53°, allowing for the possibility of a closely aligned jet. Finally, by analyzing the first pc-scale multi-epoch images of the prototypical compact symmetric object (CSO) PKS 1718−649, we place an upper limit on the separation speed between the two mini-lobes. This in turn allows us to derive a lower limit on the age of the source. Conclusions. We can draw some preliminary conclusions on the relationship between pc-scale jets and γ-ray emission in radio galaxies, based on Fermi-LAT-detected sources with available multi-epoch VLBI measurements. We find that the VLBI core flux density correlates with the γ-ray flux, as seen in blazars. On the other hand, the γ-ray luminosity does not show any dependence on the core brightness temperature and core dominance, which are two common indicators of jet Doppler boosting. This seems to indicate that γ-ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, in accordance with the unified model of jetted AGN.

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 Gamma-ray observations and the large scale structure of the galaxy

1979 ◽  
Vol 84 ◽  
pp. 125-130
Author(s):  
J. A. Paul
Keyword(s):  
Present Status ◽  
Large Scale ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Large Scale Structure ◽  
Galactic Disc ◽  
Γ Radiation ◽  
Latitude Dependence ◽  
The Galaxy ◽  
Γ Ray

Within the last few years, γ-ray astronomy has shifted from the discovery phase to the exploratory phase, thanks to the SAS-2 and COS-B satellites. The strongest feature of the γ-ray sky is the overwhelming emission of the galactic disc; even the radiation observed away from the galactic plane appears to be predominantly galactic, on the basis of its latitude dependence (Fichtel et al., 1978). Nevertheless, extragalactic γ-ray astronomy is not hopeless: the γ-radiation of the nearby quasar 3C273 has been very recently detected (Swanenburg et al., 1978). A brief summary of the present status of the galactic γ-ray astronomy follows.

scholarly journals Very high energy gamma-ray observations of the Galactic Plane with the CANGAROO-III telescopes

2008 ◽  
Vol 30 (2) ◽  
pp. 47-53 ◽  
Author(s):  
M. Ohishi ◽  
M. Mori ◽  
Y. Adachi ◽  
A. Asahara ◽  
G.V. Bicknell ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Plane ◽  
High Energy ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

scholarly journals Radio Emission from Supernova Remnants

1996 ◽  
Vol 145 ◽  
pp. 333-340
Author(s):  
Richard G. Strom
Keyword(s):  
Cosmic Rays ◽  
Radio Emission ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Energy Content ◽  
Particle Energy ◽  
The Galaxy ◽  
Radio Frequencies ◽  
Shock Fronts

Most of the supernova remnants known in the Galaxy have only been detected at radio frequencies. The reason for this is absorption in the Galactic plane at both optical and X-ray wavelengths. All available evidence suggests that the shock fronts which accompany supernova remnants accelerate enough cosmic rays to GeV energies to produce readily detectable radio emission. This is fortunate, for it enables us to study remnants throughout the Galactic disk, although existing catalogues may be anywhere from 50 to 90 % incomplete. Cosmic rays and the magnetic fields in which they gyrate are the essential ingredients for producing the synchrotron radiation which is observed at radio frequencies. Various methods for estimating magnetic field strengths can be applied to a small number of remnants, and produce values not far from those based upon equipartition between the energy contents of particles and fields. From this, the particle energy content is derived for a number of objects.

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