scholarly journals Radio Jet–Ambient Medium Interactions on Parsec Scales in the Blazar 1055+018

1999 ◽  
Vol 518 (2) ◽  
pp. L87-L90 ◽  
Author(s):  
Joanne M. Attridge ◽  
David H. Roberts ◽  
John F. C. Wardle
Keyword(s):  
Ambient Medium

scholarly journals Jet-torus connection in radio galaxies

2018 ◽  
Vol 609 ◽  
pp. A80 ◽  
Author(s):  
C. M. Fromm ◽  
M. Perucho ◽  
O. Porth ◽  
Z. Younsi ◽  
E. Ros ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Ambient Medium ◽  
Galactic Nuclei ◽  
Radio Galaxies ◽  
Asymmetric Structures ◽  
Long Baseline ◽  
Volume Method ◽  
Index Maps ◽  
Thermal Absorption ◽  
Core Shift

Context. High resolution very long baseline interferometry observations of active galactic nuclei have revealed asymmetric structures in the jets of radio galaxies. These asymmetric structures may be due to internal asymmetries in the jets or they may be induced by the different conditions in the surrounding ambient medium, including the obscuring torus, or a combination of the two. Aims. In this paper we investigate the influence of the ambient medium, including the obscuring torus, on the observed properties of jets from radio galaxies. Methods. We performed special-relativistic hydrodynamic (SRHD) simulations of over-pressured and pressure-matched jets using the special-relativistic hydrodynamics code Ratpenat, which is based on a second-order accurate finite-volume method and an approximate Riemann solver. Using a newly developed radiative transfer code to compute the electromagnetic radiation, we modelled several jets embedded in various ambient medium and torus configurations and subsequently computed the non-thermal emission produced by the jet and thermal absorption from the torus. To better compare the emission simulations with observations we produced synthetic radio maps, taking into account the properties of the observatory. Results. The detailed analysis of our simulations shows that the observed properties such as core shift could be used to distinguish between over-pressured and pressure matched jets. In addition to the properties of the jets, insights into the extent and density of the obscuring torus can be obtained from analyses of the single-dish spectrum and spectral index maps.

scholarly journals The dynamic ejecta of compact object mergers and eccentric collisions

2013 ◽  
Vol 371 (1992) ◽  
pp. 20120272 ◽  
Author(s):  
Stephan Rosswog
Keyword(s):  
Globular Clusters ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Compact Object ◽  
Solar Mass ◽  
Abundance Pattern ◽  
Compact Binary ◽  
Hydrodynamical Simulations ◽  
Rich Material ◽  
R Process

Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the ‘heavy’ ( A >130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta (‘macronovae’), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.

scholarly journals Optical Afterglows as Probes for the Central Engine and Fireball of Gamma-Ray Bursts

2012 ◽  
Vol 8 (S290) ◽  
pp. 263-264
Author(s):  
Liang Li ◽  
En-Wei Liang ◽  
He Gao ◽  
Bing Zhang
Keyword(s):  
Statistical Analysis ◽  
Gamma Rays ◽  
Density Profile ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Medium Density ◽  
Central Engine ◽  
Prompt Emission

AbstractWell-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from literature. We identify possible emission components based on our empirical fits and present statistical analysis for these components. We find that the flares are related to prompt emission, suggesting that they could have the same origin in different episodes. The shallow decay segment is not correlated with prompt gamma-rays. It likely signals a long-lasting injected wind from GRB central engines. Early after onset peak is closely related with prompt emission. The ambient medium density profile is likely n ∝ r−1. No correlation between the late re-brightening bump and prompt gamma-rays or the onset bump is found. They may be from another jet component.

scholarly journals The Close AGN Reference Survey (CARS)

2018 ◽  
Vol 618 ◽  
pp. A27 ◽  
Author(s):  
M. C. Powell ◽  
B. Husemann ◽  
G. R. Tremblay ◽  
M. Krumpe ◽  
T. Urrutia ◽  
...  
Keyword(s):  
Ambient Medium ◽  
Theoretical Models ◽  
Ionized Gas ◽  
X Ray ◽  
Gas Streams ◽  
Hot Gas ◽  
Upper Limits ◽  
Theoretical Predictions ◽  
Different Origins

Aims. We probe the radiatively-efficient, hot wind feedback mode in two nearby luminous unobscured (type 1) AGN from the Close AGN Reference Survey (CARS), which show intriguing kpc-scale arc-like features of extended [O III]ionized gas as mapped with VLT-MUSE. We aimed to detect hot gas bubbles that would indicate the existence of powerful, galaxy-scale outflows in our targets, HE 0227–0931 and HE 0351+0240, from deep (200 ks) Chandra observations. Methods. By measuring the spatial and spectral properties of the extended X-ray emission and comparing with the sub kpc-scale IFU data, we are able to constrain feedback scenarios and directly test if the ionized gas is due to a shocked wind. Results. No extended hot gas emission on kpc-scales was detected. Unless the ambient medium density is low (n H  ∼  1 cm−3 at 100 pc), the inferred upper limits on the extended X-ray luminosities are well below what is expected from theoretical models at matching AGN luminosities. Conclusions. We conclude that the highly-ionized gas structures on kpc scales are not inflated by a hot outflow in either target, and instead are likely caused by photoionization of pre-existing gas streams of different origins. Our nondetections suggest that extended X-ray emission from an AGN-driven wind is not universal, and may lead to conflicts with current theoretical predictions.

scholarly journals A Novel Method for Estimating the Ambient Medium Density Around Distant Radio Sources from Their Observed Radio Spectra

2021 ◽  
Vol 922 (2) ◽  
pp. 197
Author(s):  
Anna Wójtowicz ◽  
Łukasz Stawarz ◽  
Jerzy Machalski ◽  
Luisa Ostorero
Keyword(s):  
Radio Emission ◽  
Ambient Medium ◽  
Radio Galaxies ◽  
Radiative Properties ◽  
Radio Continuum ◽  
Physical Parameters ◽  
Radio Sources ◽  
Data Set ◽  
Radio Structure ◽  
5 Ghz

Abstract The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FR II type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e., sampling the broadband radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here, we analyze the best-fit values of the source physical parameters, derived from extensive modeling of the largest currently available sample of FR II radio sources, for which good-quality multiwavelength radio flux measurements could be collected. In the analyzed data set, we notice a significant and nonobvious correlation between the spectral index of the nonthermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely, the slope of the radio continuum between the rest-frame frequencies 0.4 and 5 GHz, possibly combined with the total linear size of the radio structure.

scholarly journals HYDRODYNAMICAL INTERACTION OF MILDLY RELATIVISTIC EJECTA WITH AN AMBIENT MEDIUM

2016 ◽  
Vol 834 (1) ◽  
pp. 32 ◽  
Author(s):  
Akihiro Suzuki ◽  
Keiichi Maeda ◽  
Toshikazu Shigeyama
Keyword(s):  
Ambient Medium ◽  
Hydrodynamical Interaction

Mechanisms Regulating the Renal Transport of p-Aminohippurate

1957 ◽  
Vol 191 (1) ◽  
pp. 50-54 ◽  
Author(s):  
Abraham G. White
Keyword(s):  
Guinea Pig ◽  
Intraperitoneal Injection ◽  
Ambient Medium ◽  
Renal Transport ◽  
Tissue Cells

The uptake of PAH was studied by the method of Cross and Taggart. Secretion was studied in two ways: a) measuring the movement of PAH into the ambient medium from renal slices which had been preloaded with PAH by the intraperitoneal injection of this compound into rats 40 minutes before killing, and b) measuring the uptake of PAH by guinea-pig renal slices, its rate of acetylation, and the movement of the newly-formed paraacetylaminohippurate (PAAH) from the tissue cells into the medium. The velocity of secretion is approximately 5–7 times that of uptake. Uptake is inhibited by 2,4-dinitrophenol, cyanide and Pentothal, while secretion is not. Pentothal also blocks the stimulatory effect of acetate on the uptake of PAH. The interpretation of the effects of Pentothal, with regard to the mechanism of the stimulatory effect of acetate on uptake, is discussed.

scholarly journals The radio morphology of quasars at high redshift

1986 ◽  
Vol 119 ◽  
pp. 181-184 ◽  
Author(s):  
P. D. Barthel
Keyword(s):  
Ambient Medium ◽  
High Redshift ◽  
Radio Sources ◽  
Evolution Of The Universe ◽  
The Universe

The mapping at kpc-scale resolution of the radio sources associated with quasars is fascinating, since it provides us with morphological information on a population of objects during 1010.3 y evolution of the universe, as well as information on a possible epoch dependence of the influence of the ambient medium on the properties of these objects.

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