scholarly journals The obstructed jet in Mrk 231

2021 ◽  
Author(s):  
Ailing Wang ◽  
Tao An ◽  
Sumit Jaiswal ◽  
Prashanth Mohan ◽  
Yuchan Wang ◽  
...  
Keyword(s):  
Large Scale ◽  
Position Angle ◽  
Opening Angle ◽  
Luminous Infrared Galaxies ◽  
Multi Scale ◽  
Long Baseline ◽  
Relativistic Jet ◽  
Multi Phase ◽  
Jet Structure ◽  
Projected Distance

Abstract Mrk 231 is the closest radio-quiet quasar known and one of the most luminous infrared galaxies in the local Universe. It is characterised by the co-existence of a radio jet and powerful multi-phase multi-scale outflows, making it an ideal laboratory to study active galactic nucleus (AGN) feedback. We analyse the multi-epoch very long baseline interferometry data of Mrk 231 and estimate the jet head advance speed to be ≲ 0.013 c, suggesting a sub-relativistic jet flow. The jet position angle changes from −113○ in the inner parsec to −172○ at a projected distance of 25 parsec. The jet structure change might result from either a jet bending following the rotation of the circum-nuclear disc or the projection of a helical jet on the plane of the sky. In the large opening angle (∼60○) cone, the curved jet interacts with the interstellar medium and creates wide-aperture-angle shocks which subsequently dissipate a large portion of the jet power through radiation and contribute to powering the large-scale outflows. The low power and bent structure of the Mrk 231 jet, as well as extensive radiation dissipation, are consistent with the obstruction of the short-length jet by the host galaxy’s environment.

scholarly journals Radio jet structures at ∼100 pc and larger scales of the γ-ray-emitting narrow-line Seyfert 1 galaxy PMN J0948+0022

2019 ◽  
Vol 487 (1) ◽  
pp. 640-649 ◽  
Author(s):  
Akihiro Doi ◽  
Satomi Nakahara ◽  
Masanori Nakamura ◽  
Motoki Kino ◽  
Nozomu Kawakatu ◽  
...  
Keyword(s):  
Large Scale ◽  
Ambient Pressure ◽  
Position Angle ◽  
Host Galaxy ◽  
Narrow Line ◽  
Very Large Array ◽  
Long Baseline ◽  
Radio Lobe ◽  
Γ Ray ◽  
Very Long Baseline Array

Abstract The narrow-line Seyfert 1 (NLS1) galaxy PMN J0948+0022 is an archetype of γ-ray-emitting NLS1s in active galactic nuclei (AGNs). In this study, we investigate its radio structures using archival data obtained using the Karl G. Jansky Very Large Array (VLA) and the Very Long Baseline Array (VLBA). The new VLA images reveal an outermost radio emission separated by 9.1 arcsec. Its resolved structure and steep spectrum suggest a terminal shock in a radio lobe energized by the jet from the PMN J0948+0022 nucleus. This large-scale radio component is found at almost the same position angle as that of the pc-scale jet, indicating a stable jet direction up to ∼1 Mpc. Its apparent one-sidedness implies a moderate advancing speed (β > 0.27). The kinematic age of <1× 107 yr of the jet activity is consistent with the expected NLS1 phase of ∼107 yr in the AGN lifetime. The VLBA image reveals the jet structure at distances ranging from r = 0.82 milliarcsec to 3.5 milliarcsec, corresponding to approximately 100 pc, where superluminal motions were found. The jet width profile (∝ r1.12) and flux-density profile (∝ r−1.44) depending on the distance r along the jet suggest that the jet kinetic energy is converted to internal energy in this region. The jet is causally connected in a nearly conical streamline, which is supported by ambient pressure at 100 pc scales in the host galaxy of PMN J0948+0022.

scholarly journals Proper motion of water masers near NGC1333-SVS13

2002 ◽  
Vol 206 ◽  
pp. 100-103 ◽  
Author(s):  
Alwyn Wootten ◽  
Mark Claussen ◽  
Kevin Marvel ◽  
Bruce Wilking
Keyword(s):  
Proper Motion ◽  
Position Angle ◽  
Opening Angle ◽  
Doppler Shifts ◽  
Water Masers ◽  
Driving Source ◽  
Projected Distance ◽  
Co Observations ◽  
Over Time ◽  
The Continuum

VLBA observations of water masers toward the region of NGC1333 near SVS13, the driving source for the well-known Herbig-Haro objects HH7-11, are reported. Maser emission was observed over four epochs spaced by three weeks during late 1998. SVS13 is associated with the millimeter continuum SED Class I source SSV13A1. High resolution CO observations have secured the association of the flow with the continuum object on arc-second scales. A 1998 Aug 12 VLA observation places the blueshifted masers within 80 AU (0.2) of the 2.7 mm position for A1 reported from BIMA. We report observations of two groups of masers, one redshifted by about 6 km s−1 and one blueshifted by about 2-3 km s−1, separated by about 100 AU in projected distance along position angle 21 degrees. Redshifted masers were present only in the latter two epochs. During all epochs, an arclike structure was present with similar morphology; over time this structure moved relative to the southernmost blue maser toward the southeast, roughly along the position angle defined by the Herbig-Haro objects, with a proper motion of about 13 km s−1. Both redshifted and blueshifted masers are clearly part of the same lobe of the flow; their observed Doppler shifts are artifacts of the opening angle of the flow. Our data suggest that the opening angle is about 10°. We measure lower expansion velocities and a wider opening angle than has been found in some other flows near Class 0 SED objects, perhaps indicating that the flows open and slow as they age.

scholarly journals J1110+4817 – a compact symmetric object candidate revisited

2020 ◽  
Vol 496 (2) ◽  
pp. 1811-1818 ◽  
Author(s):  
Máté Krezinger ◽  
Sándor Frey ◽  
Tao An ◽  
Sumit Jaiswal ◽  
Yingkang Zhang
Keyword(s):  
Large Scale ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Nuclear Activity ◽  
Radio Structure ◽  
Long Baseline ◽  
Extended Radio ◽  
Evolutionary Phase ◽  
Resolution Imaging ◽  
Jet Structure

ABSTRACT Compact symmetric objects (CSOs) are radio-emitting active galactic nuclei (AGNs) typically with a double-lobed radio structure confined to within 1 kpc. CSOs represent the earliest evolutionary phase of jetted AGNs. Some of them may eventually evolve into large-scale extended double sources, while others stall within the host galaxy and die out, depending on the longevity of nuclear activity, the jet power, and parameters of the surrounding galactic environment. Studying CSOs is a useful tool for understanding the evolution of the galaxies and the interactions between the jets and the medium of the host galaxy. Based on milliarcsec-resolution imaging observations using very long baseline interferometry (VLBI), it is not always straightforward to distinguish between a compact double-lobed or a core–jet structure. The quasar J1110+4817 was considered a CSO candidate in the literature earlier, but because of the lack of clear evidence, it could not be securely classified as a CSO. Here we present a comprehensive analysis of archival multifrequency VLBI observations combined with accurate Gaia optical astrometric information. Lower frequency VLBI images reveal an extended radio feature nearly perpendicular to the main structural axis of the source, apparently emanating from the brighter northern feature, which is rare among the known CSOs. While the presence of a binary AGN system cannot be fully excluded, the most plausible explanation is that J1110+4817 is a CSO.

scholarly journals The central pc-scale region in blazars: insights from multi-band observations

2013 ◽  
Vol 9 (S304) ◽  
pp. 257-260
Author(s):  
Tigran G. Arshakian ◽  
Vahram Chavushyan
Keyword(s):  
Black Hole ◽  
High Energy ◽  
Opening Angle ◽  
Radiation Mechanisms ◽  
Long Baseline ◽  
Empirical Relations ◽  
Relativistic Jet ◽  
Line Region ◽  
Γ Ray ◽  
Very Long Baseline Array

AbstractThe empirical relations in the black hole-accretion disk-relativistic jet system and physical processes behind these relations are still poorly understood, partly because they operate close to the black hole within the central light year. Very long baseline array (VLBA) provides unparalleled resolution at 15 GHz with which to observe the jet components at sub-milliarcsecond scales, corresponding to sub-pc-scales for local blazars. We discuss the jet inner structure of blazars, location and radiation mechanisms operating in the innermost parsec-scale region of blazars, and evidence for jet-excited broad-line region (BLR) ouflowing downstream the jet. Outflowing BLR can provide necessary conditions for production of high energy emission along the jet between the base of the jet and the BLR and far beyond the BLR as evidenced by recent observations. Flat spectrum quasars and low synchrotron peaked sources are the most likely objects to host the outfllowing BLR. From the γ-ray absorption arguments, we propose that the jet-excited region of the outflowing BLR in quasars is small and/or gas filling factor is low, and that the orientation and opening angle of the outflowing BLR can lead to relevant γ-ray absorption features observed in quasars.

A helically twisted relativistic jet: nonradial motions and accelerations in 3C345

1986 ◽  
Vol 64 (4) ◽  
pp. 484-487 ◽  
Author(s):  
Philip E. Hardee
Keyword(s):  
Radio Source ◽  
Position Angle ◽  
Dynamical Equations ◽  
Parallel Straight Line ◽  
Helical Twist ◽  
Nonlinear Motion ◽  
Straight Line ◽  
Relativistic Jet ◽  
Jet Structure ◽  
Apparent Acceleration

The radio source 3C 345 has a curved, inner-jet structure consisting of three components. Components C2 and C3 appear to be moving with βapp ~ 17 and 13, respectively, along approximately parallel straight-line trajectories with motion along a mean direction ~ −75°. Component C4 recently appeared at a position angle ~ −135° and has exhibited nonlinear motion and apparent acceleration from βapp ~ 4–10 over a period of about 2 years with motion along a mean direction < −75°. We show how the motions of C4 can be explained by a feature that is propagating with constant speed along a helically twisted jet in which the wavelength of the helix increases in proportion to the jet's radius. This form for a helical twist is predicted by the linearized fluid-dynamical equations, which can be used to describe the response of a light jet to helical distortion.

scholarly journals Public Awareness: What Climate Change Scientists Should Consider

2020 ◽  
Vol 12 (20) ◽  
pp. 8369
Author(s):  
Mohammad Rahimi
Keyword(s):  
Climate Change ◽  
Social Media ◽  
Large Scale ◽  
Public Awareness ◽  
Connected Network ◽  
Multi Scale ◽  
Valuable Addition ◽  
Scientific Approach ◽  
Design Solutions ◽  
Mitigate Climate Change

In this Opinion, the importance of public awareness to design solutions to mitigate climate change issues is highlighted. A large-scale acknowledgment of the climate change consequences has great potential to build social momentum. Momentum, in turn, builds motivation and demand, which can be leveraged to develop a multi-scale strategy to tackle the issue. The pursuit of public awareness is a valuable addition to the scientific approach to addressing climate change issues. The Opinion is concluded by providing strategies on how to effectively raise public awareness on climate change-related topics through an integrated, well-connected network of mavens (e.g., scientists) and connectors (e.g., social media influencers).

scholarly journals Multi-Scale Ionospheric Anomalies Monitoring and Spatio-Temporal Analysis during Intense Storm

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 215
Author(s):  
Na Cheng ◽  
Shuli Song ◽  
Wei Li
Keyword(s):  
Magnetic Storm ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Ionospheric Disturbance ◽  
Ionospheric Scintillation ◽  
Small Scale ◽  
Electron Content ◽  
Total Electron ◽  
Multi Scale ◽  
Intense Storm

The ionosphere is a significant component of the geospace environment. Storm-induced ionospheric anomalies severely affect the performance of Global Navigation Satellite System (GNSS) Positioning, Navigation, and Timing (PNT) and human space activities, e.g., the Earth observation, deep space exploration, and space weather monitoring and prediction. In this study, we present and discuss the multi-scale ionospheric anomalies monitoring over China using the GNSS observations from the Crustal Movement Observation Network of China (CMONOC) during the 2015 St. Patrick’s Day storm. Total Electron Content (TEC), Ionospheric Electron Density (IED), and the ionospheric disturbance index are used to monitor the storm-induced ionospheric anomalies. This study finally reveals the occurrence of the large-scale ionospheric storms and small-scale ionospheric scintillation during the storm. The results show that this magnetic storm was accompanied by a positive phase and a negative phase ionospheric storm. At the beginning of the main phase of the magnetic storm, both TEC and IED were significantly enhanced. There was long-duration depletion in the topside ionospheric TEC during the recovery phase of the storm. This study also reveals the response and variations in regional ionosphere scintillation. The Rate of the TEC Index (ROTI) was exploited to investigate the ionospheric scintillation and compared with the temporal dynamics of vertical TEC. The analysis of the ROTI proved these storm-induced TEC depletions, which suppressed the occurrence of the ionospheric scintillation. To improve the spatial resolution for ionospheric anomalies monitoring, the regional Three-Dimensional (3D) ionospheric model is reconstructed by the Computerized Ionospheric Tomography (CIT) technique. The spatial-temporal dynamics of ionospheric anomalies during the severe geomagnetic storm was reflected in detail. The IED varied with latitude and altitude dramatically; the maximum IED decreased, and the area where IEDs were maximum moved southward.

scholarly journals Multi-scale modelling of a large scale shell-and-tube latent heat storage system for direct steam generation power plants

2020 ◽  
Author(s):  
Clément Beust ◽  
Erwin Franquet ◽  
Jean-Pierre Bédécarrats ◽  
Pierre Garcia ◽  
Jérôme Pouvreau ◽  
...  
Keyword(s):  
Power Plants ◽  
Large Scale ◽  
Storage System ◽  
Steam Generation ◽  
Latent Heat Storage ◽  
Multi Scale ◽  
Direct Steam ◽  
Scale Modelling ◽  
Shell And Tube ◽  
Generation Power

scholarly journals Temperature Resistance of Mo3Si: Phase Stability, Microhardness, and Creep Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 564 ◽  
Author(s):  
Olha Kauss ◽  
Susanne Obert ◽  
Iurii Bogomol ◽  
Thomas Wablat ◽  
Nils Siemensmeyer ◽  
...  
Keyword(s):  
Power Law ◽  
Phase Stability ◽  
Gas Turbines ◽  
Constitutive Models ◽  
Creep Properties ◽  
Multi Scale ◽  
Scale Modeling ◽  
Significant Difference ◽  
Before And After ◽  
Multi Phase

Mo-Si-B alloys are one of the most promising candidates to substitute Ni based superalloys in gas turbines. The optimization of their composition can be achieved more effectively using multi-scale modeling of materials behavior and structural analysis of components for understanding, predicting, and screening properties of new alloys. Nevertheless, this approach is dependent on data on the properties of the single phases in these alloys. The focus of this investigation is Mo3Si, one of the phases in typical Mo-Si-B alloys. The effect of 100 h annealing at 1600 °C on phase stability and microhardness of its three near-stoichiometric compositions—Mo-23Si, Mo-24Si and Mo-25Si (at %)—is reported. While Mo-23Si specimen consist only of Mo3Si before and after annealing, Mo-24Si and Mo-25Si comprise Mo5Si3 and Mo3Si before annealing. The latter is then increased by the annealing. No significant difference in microhardness was detected between the different compositions as well as after annealing. The creep properties of Mo3Si are described at 1093 °C and 1300 °C at varying stress levels as well as at 300 MPa and temperatures between 1050 °C and 1350 °C. Three constitutive models were used for regression of experimental results—(i) power law with a constant creep exponent, (ii) stress range dependent law, and (iii) power law with a temperature-dependent creep exponent. It is confirmed that Mo3Si has a higher creep resistance than Moss and multi-phase Mo-Si-B alloys, but a lower creep strength as compared to Mo5SiB2.

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