scholarly journals Spatially resolved origin of millimeter-wave linear polarization in the nuclear region of 3C 84

2019 ◽  
Vol 622 ◽  
pp. A196 ◽  
Author(s):  
J.-Y. Kim ◽  
T. P. Krichbaum ◽  
A. P. Marscher ◽  
S. G. Jorstad ◽  
I. Agudo ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Core Region ◽  
Polarization Degree ◽  
Large Rotation ◽  
The Core ◽  
Spatially Resolved ◽  
Long Baseline ◽  
Rotation Measure ◽  
Jet Plasma ◽  
Ngc 1275

We report results from a deep polarization imaging of the nearby radio galaxy 3C 84 (NGC 1275). The source was observed with the Global Millimeter VLBI Array (GMVA) at 86 GHz at an ultrahigh angular resolution of 50 μas (corresponding to ∼200Rs). We also add complementary multiwavelength data from the Very Long Baseline Array (VLBA; 15 and 43 GHz) and from the Atacama Large Millimeter/submillimeter Array (ALMA; 97.5, 233.0 and 343.5 GHz). At 86 GHz, we measured a fractional linear polarization of ∼2% in the VLBI core region. The polarization morphology suggests that the emission is associated with an underlying limb-brightened jet. The fractional linear polarization is lower at 43 and 15 GHz (∼0.3−0.7% and <0.1%, respectively). This suggests an increasing linear polarization degree toward shorter wavelengths on VLBI scales. We also obtain a large rotation measure (RM) of ∼105–6 rad m2 in the core at ≳43 GHz. Moreover, the VLBA 43 GHz observations show a variable RM in the VLBI core region during a small flare in 2015. Faraday depolarization and Faraday conversion in an inhomogeneous and mildly relativistic plasma could explain the observed linear polarization characteristics and the previously measured frequency dependence of the circular polarization. Our Faraday depolarization modeling suggests that the RM most likely originates from an external screen with a highly uniform RM distribution. To explain the large RM value, the uniform RM distribution and the RM variability, we suggest that the Faraday rotation is caused by a boundary layer in a transversely stratified jet. Based on the RM and the synchrotron spectrum of the core, we provide an estimate for the magnetic field strength and the electron density of the jet plasma.

scholarly journals A parsec-scale wobbling jet in the high-synchrotron peaked blazar PG 1553+113

2020 ◽  
Vol 634 ◽  
pp. A87 ◽  
Author(s):  
R. Lico ◽  
J. Liu ◽  
M. Giroletti ◽  
M. Orienti ◽  
J. L. Gómez ◽  
...  
Keyword(s):  
Light Curve ◽  
Intrinsic Value ◽  
Position Angle ◽  
Core Region ◽  
Periodic Pattern ◽  
Owens Valley ◽  
The Core ◽  
Long Baseline ◽  
Rotation Measure ◽  
Geometrical Effects

Context. The detection of quasi-periodic variability in active galactic nuclei in general, and in blazars in particular, is key to our understanding of the origin and nature of these objects as well as their cosmological evolution. PG 1553+113 is the first blazar showing an approximately two-year quasi-periodic pattern in its γ-ray light curve, which is also revealed at optical frequencies. Aims. Such quasi-periodicity might have a geometrical origin, possibly related to the precessing nature of the jet, or could be intrinsic to the source and related to pulsational accretion flow instabilities. In this work we investigate and characterise the high-resolution radio emission properties of PG 1553+113 on parsec scales in order to differentiate between these different physical scenarios. Methods. We monitored the source with the very long baseline array (VLBA) at 15, 24, and 43 GHz during an entire cycle of γ-ray activity in the period 2015–2017, with a cadence of about 2 months, both in total and polarised intensity. We constrained the jet position angle across the different observing epochs by investigating the total intensity ridge lines. Results. We find a core-dominated source with a limb-brightened jet structure extending for ∼1.5 mas in the northeast direction whose position angle varies in time in the range ∼40°−60°. No clear periodic pattern can be recognized in the VLBA light curves during 2015–2017 or in the 15 GHz Owens Valley Radio Observatory light curve during the period 2008–2018. The core region polarisation percentage varies in the range ∼1−4%, and the polarisation angle varies from being roughly parallel to roughly transverse to the jet axis. We estimate a rotation measure value in the core region of ∼−1.0 ± 0.4 × 104 rad m−2. The brightness temperature (TB) is found to decrease as the frequency increases with an intrinsic value of ∼1.5 × 1010 K and the estimated Doppler factor is ∼1.4. Conclusions. Although the jet wobbling motion indicates that geometrical effects can produce an enhanced emission through the Doppler boosting modulation, additional mechanisms are required in order to account for the quasi-periodic variability patterns observed in γ rays. The intrinsic TB value indicates that the total energy in the core region is dominated by the magnetic field.

scholarly journals On the Time Variable Rotation Measure in the Core Region of Markarian 421

Galaxies ◽  
2017 ◽  
Vol 5 (4) ◽  
pp. 57 ◽  
Author(s):  
Rocco Lico ◽  
José Gómez ◽  
Keiichi Asada ◽  
Antonio Fuentes
Keyword(s):  
Time Variable ◽  
Core Region ◽  
Markarian 421 ◽  
The Core ◽  
Rotation Measure

Intramitochondrial Viruses of Reptilian Cell Origin

1972 ◽  
Vol 30 ◽  
pp. 318-319
Author(s):  
Philip D. Lunger ◽  
H. Fred Clark
Keyword(s):  
Particle Production ◽  
Outer Zone ◽  
Density Variation ◽  
Core Region ◽  
Mitochondrial Membranes ◽  
Virus Particles ◽  
The Core ◽  
Vipera Russelli ◽  
Maturation Stages ◽  
Type Particle

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.

scholarly journals On the Nature of R 136, the Central Object of 30 Dor. A Comparison by the Galactic Cluster NGC 3603

1984 ◽  
Vol 108 ◽  
pp. 257-258
Author(s):  
Michael Rosa ◽  
Jorge Melnick ◽  
Preben Grosbol
Keyword(s):  
Core Region ◽  
H Ii Regions ◽  
Central Object ◽  
The Core ◽  
Dominant Component ◽  
Galactic Cluster ◽  
H Ii Region

The massive H II region NGC 3603 is the closest galactic counterpart to the giant LMC nebula 30 Dor. Walborn (1973) first compared the ionizing OB/WR clusters of the two H II regions and suggested that R 136, the unresolved luminous WR + 0 type central object of 30 Dor, might be a multiple system like the core region of NGC 3603. Suggestions that the dominant component of R 136, i.e. R 136A, might be either a single or a very few supermassive and superluminous stars (Schmidt-Kaler and Feitzinger 1982, Savage et al. 1983) have recently been disputed by Moffat and Seggewiss (1983) and Melnick (1983), who have presented spectroscopic and photometric evidence to support the hypothesis of an unresolved cluster of stars. We have extended Walborn's original comparison of the apparent morphology of the two clusters by digital treatment of the images to simulate how the galactic cluster would look like if it were located in the LMC

Comparison of linear polarization degree in healthy and wounded rat skin

2001 ◽  
Author(s):  
Martha S. Ribeiro ◽  
Anderson Z. Freitas ◽  
Daniela F. Silva ◽  
Denise M. Zezell ◽  
Cleusa M. R. Pellegrini ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Polarization Degree ◽  
Rat Skin

scholarly journals Spatially resolved studies of extragalactic jets in high redshift radio galaxies

2014 ◽  
Vol 10 (S313) ◽  
pp. 231-235
Author(s):  
Leah K. Morabito ◽  
Adam Deller ◽  
J. B. R. Oonk ◽  
Huub Röttgering ◽  
George Miley
Keyword(s):  
High Redshift ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spatially Resolved ◽  
Long Baseline ◽  
Early Results ◽  
Spectrum Radio ◽  
Extragalactic Jets ◽  
Frequency Survey

AbstractThe correlation between radio spectral steepness and redshift has been successfully used to find high redshift (z ⩾ 2) radio galaxies, but the origin of this relation is unknown. The ultra-steep spectra of high-z radio sources make them ideally suited for studies with the Low Band Antenna of the new Low Frequency Array, which covers 10–80 MHz and has baselines up to about 1300 km. As part of an ongoing survey, we use the longest baselines to map the low-frequency (< 70 MHz) spatial distributions along the jets of 5 bright extended steep spectrum high-z radio sources. From this, we will determine whether the spectra change over these spatially resolved sources, thereby constraining particle acceleration processes. We present early results from our low-frequency survey of ultra-steep spectrum radio galaxies. The first low frequency long baseline images of these objects are presented.

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.

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