STRUCTURE AND EMISSION OF COMPACT BLAZAR JETS

2012 ◽  
Vol 08 ◽  
pp. 151-162 ◽  
Author(s):  
ALAN P. MARSCHER
Keyword(s):  
Millimeter Wave ◽  
Position Angle ◽  
Turbulent Plasma ◽  
Time Variability ◽  
Relativistic Jets ◽  
X Ray ◽  
The Core ◽  
Central Engine ◽  
Conical Shock ◽  
Jet Plasma

Relativistic jets in blazars on parsec scales can now be explored with direct imaging at radio wavelengths as well as observations of time variability of flux and linear polarization at various wavebands. The results thus far suggest that the millimeter-wave "core" is usually a standing, conical shock and that the jet plasma is turbulent. Disturbances and turbulent plasma crossing the standing shock can explain much of the observed variability, as well as the appearance of bright knots moving down the jet at superluminal apparent speeds. The core, located parsecs downstream of the central engine, appears to be the site of many of the outbursts observed at optical, X-ray, and γ-ray energies. Rotations in the optical polarization position angle prior to the passage of a knot through the millimeter-wave core provide evidence for helical magnetic fields that accelerate and collimate the jet before turbulence tangles the fields.

The origin of X-ray emission in Low-Excitation Radio Galaxies

2019 ◽  
Vol 15 (S356) ◽  
pp. 243-246
Author(s):  
Shuang-Liang Li
Keyword(s):  
Accretion Disk ◽  
Radio Galaxies ◽  
Fundamental Plane ◽  
X Ray ◽  
Accretion Flow ◽  
The Core ◽  
Central Engine ◽  
Different Origin

AbstractIn previous works, the radio-X-ray slope in FRI radio galaxies is found to be steeper compared with that in low-luminosity AGNs, indicating different origin of the X-ray emission. Here we reinvestigate this point by compiling a sample of 13 low-excitation radio galaxies (LERG) from 3CR radio catalog of galaxies, where the central engine in LERG is accepted to be a radiatively inefficient accretion flow (RIAF). The core radio and X-ray emissions in all the objects of our sample are detected by VLA/VLBI/VLBA and Chandra/XMM-Newton, respectively. Surprisingly, a shallower slope of Lr – Lx relation () is given by our sample, which demonstrates that the X-ray emission in LERG may come from accretion disk rather than a jet as suggested by previous works. In addition, the slope in the fundamental plane ((log LR = 0.52 log LX + 0.84 log MBH + 10.84) of LERG is found to be well consistent with that reported by Merloni et al. (2003).

scholarly journals Variability in Active Galactic Nuclei

1993 ◽  
Vol 134 ◽  
pp. 245-547
Author(s):  
M. Matsuoka
Keyword(s):  
Active Galactic Nuclei ◽  
Time Scales ◽  
Galactic Nuclei ◽  
Wide Band ◽  
Seyfert Galaxies ◽  
Time Variability ◽  
X Ray ◽  
Central Engine ◽  
Nearby Region ◽  
Wide Range

AbstractAGN (Active Galactic Nuclei) have their profound time variability over a wide range of time scales. Although many results of AGN variability have been provided from wide band wavelength observations, I would like to concentrate the recent problems concerning a nearby region of their central engine based on the X-ray observations which are most efficient to investigate this region. In this paper we will investigate mainly the result of Seyfert galaxies which would be generalized to other AGN.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

scholarly journals Spectral index-flux relation for investigating the origins of steep decay in γ-ray bursts

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Samuele Ronchini ◽  
Gor Oganesyan ◽  
Marica Branchesi ◽  
Stefano Ascenzi ◽  
Maria Grazia Bernardini ◽  
...  
Keyword(s):  
Spectral Index ◽  
Proton Synchrotron ◽  
Relativistic Jets ◽  
Time Resolved ◽  
X Ray ◽  
Compact Binary ◽  
Internal Dissipation ◽  
Adiabatic Cooling ◽  
Alternative Scenarios ◽  
Steep Decay

Abstractγ-ray bursts (GRBs) are short-lived transients releasing a large amount of energy (1051 − 1053 erg) in the keV-MeV energy range. GRBs are thought to originate from internal dissipation of the energy carried by ultra-relativistic jets launched by the remnant of a massive star’s death or a compact binary coalescence. While thousands of GRBs have been observed over the last thirty years, we still have an incomplete understanding of where and how the radiation is generated in the jet. Here we show a relation between the spectral index and the flux found by investigating the X-ray tails of bright GRB pulses via time-resolved spectral analysis. This relation is incompatible with the long standing scenario which invokes the delayed arrival of photons from high-latitude parts of the jet. While the alternative scenarios cannot be firmly excluded, the adiabatic cooling of the emitting particles is the most plausible explanation for the discovered relation, suggesting a proton-synchrotron origin of the GRB emission.

scholarly journals On the relation between mini-halos and AGN feedback in clusters of galaxies

2020 ◽  
Vol 499 (2) ◽  
pp. 2934-2958
Author(s):  
A Richard-Laferrière ◽  
J Hlavacek-Larrondo ◽  
R S Nemmen ◽  
C L Rhea ◽  
G B Taylor ◽  
...  
Keyword(s):  
Large Scale ◽  
State Of The Art ◽  
Vital Role ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
X Ray ◽  
Core Cluster ◽  
Central Galaxy ◽  
Central Regions ◽  
Radio Power

ABSTRACT A variety of large-scale diffuse radio structures have been identified in many clusters with the advent of new state-of-the-art facilities in radio astronomy. Among these diffuse radio structures, radio mini-halos are found in the central regions of cool core clusters. Their origin is still unknown and they are challenging to discover; less than 30 have been published to date. Based on new VLA observations, we confirmed the mini-halo in the massive strong cool core cluster PKS 0745−191 (z = 0.1028) and discovered one in the massive cool core cluster MACS J1447.4+0827 (z = 0.3755). Furthermore, using a detailed analysis of all known mini-halos, we explore the relation between mini-halos and active galactic nucleus (AGN) feedback processes from the central galaxy. We find evidence of strong, previously unknown correlations between mini-halo radio power and X-ray cavity power, and between mini-halo and the central galaxy radio power related to the relativistic jets when spectrally decomposing the AGN radio emission into a component for past outbursts and one for ongoing accretion. Overall, our study indicates that mini-halos are directly connected to the central AGN in clusters, following previous suppositions. We hypothesize that AGN feedback may be one of the dominant mechanisms giving rise to mini-halos by injecting energy into the intra-cluster medium and reaccelerating an old population of particles, while sloshing motion may drive the overall shape of mini-halos inside cold fronts. AGN feedback may therefore not only play a vital role in offsetting cooling in cool core clusters, but may also play a fundamental role in re-energizing non-thermal particles in clusters.

scholarly journals Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

2020 ◽  
Vol 499 (4) ◽  
pp. 5986-5992
Author(s):  
Nikhil Sarin ◽  
Paul D Lasky ◽  
Gregory Ashton
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Dipole Radiation ◽  
X Ray ◽  
Radiative Efficiency ◽  
Central Engine ◽  
Radiative Losses ◽  
Wave Emission ◽  
Prompt Emission

ABSTRACT The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as $n=4.85^{+0.11}_{-0.15}$ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

scholarly journals Crystallization and Preliminary X-ray Analysis of the Core Particle of Bluetongue Virus

Virology ◽  
1995 ◽  
Vol 210 (1) ◽  
pp. 217-220 ◽  
Author(s):  
J.N. Burroughs ◽  
J.M. Grimes ◽  
P.P.C. Mertens ◽  
D.I. Stuart
Keyword(s):  
Bluetongue Virus ◽  
Core Particle ◽  
X Ray ◽  
The Core

The three-dimensional structure of interleukin-1β

1988 ◽  
Vol 16 (6) ◽  
pp. 949-953 ◽  
Author(s):  
JOHN P. PRIESTLE ◽  
HANS-PETER SCHÄR ◽  
MARKUS G. GRÜTTER
Keyword(s):  
Polypeptide Chain ◽  
Three Dimensional ◽  
Interleukin 1Β ◽  
Dimensional Structure ◽  
X Ray ◽  
Three Dimensional Structure ◽  
R Factor ◽  
The Core ◽  
Internal Sequence ◽  
Network Of Hydrogen Bonds

Summary The three-dimensional structure of human recombinant interleukin-1β has been determined at 0.24 nm resolution by X-ray crystallographic techniques. The partially refined model has a crystallographic R-factor of just under 19%. The structure is composed of 12 β-strands forming a complex network of hydrogen bonds. The core of the structure can best be described as a tetrahedron whose edges are each formed by two antiparallel β-strands. The interior of this structure is filled with hydrophobic side-chains. There is a 3-fold repeat in the folding of the polypeptide chain. Although this folding pattern suggests gene triplication, no significant internal sequence homology between topologically corresponding residues exists. The folding topology of interleukin-1β is very similar to that described by A. D. McLachlan [(1979) J. Mol. Biol. 133, 557–563] for soybean trypsin inhibitor.

Fractal X-ray time variability and spectral invariance of the Seyfert galaxy NGC5506

Nature ◽  
1987 ◽  
Vol 325 (6106) ◽  
pp. 696-698 ◽  
Author(s):  
Ian McHardy ◽  
Bozena Czerny
Keyword(s):  
Seyfert Galaxy ◽  
Time Variability ◽  
Spectral Invariance ◽  
X Ray
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