Relativistic Jets in the Radio Reference Frame Image Database. Ii. Blazar Jet Accelerations From the First 10 Years of Data (1994-2003)

Piner, B. G.; Pushkarev, A. B.; Kovalev, Y. Y.; Marvin, C. J.; Arenson, Joshua; Charlot, P.; Fey, A. L.; Collioud, A.; Voitsik, P. A.

doi:10.1088/0004-637x/758/2/84

Cited by 72 publications

(94 citation statements)

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“…Cohen et al (2014Cohen et al ( , 2015 also report that components in the jet of the IBL BL Lacertae may represent MHD waves that move at apparent speeds exceeding the bulk apparent speed, although no such components have yet been reported in an HBL jet. Because of these various effects, VLBI surveys have tended to use the fastest measured apparent speed in a jet as being the one that may be most indicative of the peak bulk apparent speed of the flow (e.g., Lister et al 2009bLister et al , 2013Lister et al , 2015Lister et al , 2016Piner et al 2012), and we have followed a similar practice in our previous work on the kinematics of TeV HBLs (Piner et al 2010;Tiet et al 2012). We continue to follow such a practice for this paper, with some necessary modifications as described below.…”

Section: Analysis and Discussionmentioning

confidence: 99%

“…Here we test to see if there are any systematic changes in apparent speed with distance from the core at the length scales probed by our current data. We have not observed individual components at a large enough number of epochs to reliably fit for accelerations of individual components as was done by, e.g., Homan et al (2009Homan et al ( , 2015 and Piner et al (2012). Instead, we use a different method also employed by Piner et al (2012).…”

Section: Superluminal Componentsmentioning

confidence: 99%

“…We have not observed individual components at a large enough number of epochs to reliably fit for accelerations of individual components as was done by, e.g., Homan et al (2009Homan et al ( , 2015 and Piner et al (2012). Instead, we use a different method also employed by Piner et al (2012). We perform a fit to ln β app versus ln r for components where motion is detected at above the 1σ level, using the measured values from Table 6, for each of the five sources with at least two such 1σ components (0229+200, 0502+675, 0706+592, 1741+196, and 2247+381).…”

Section: Superluminal Componentsmentioning

confidence: 99%

“…It is important to note that in a population of sources with equal Lorentz factors observed at various angles, the peak measured apparent speed is therefore approximately the Lorentz factor, and slow apparent speeds are observed at angles both smaller than and larger than the critical angle. Also note that patterns in the jet may not move with the bulk flow speed, but may instead be stationary or slowly moving (e.g., the Low Pattern Speed (LPS) components discussed by Lister et al 2009b andPiner et al 2012). Such components may be particularly common in the jets of HBLs due to an abundance of stationary shocks (Hervet et al 2016(Hervet et al , 2017, and any moving components may need to be observationally separated from a background of such stationary pattern speed components.…”

Section: Introductionmentioning

confidence: 99%

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Multi-epoch VLBA Imaging of 20 New TeV Blazars: Apparent Jet Speeds

Piner

Edwards

2018

ApJ

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We present 88 multi-epoch Very Long Baseline Array (VLBA) images (most at an observing frequency of 8 GHz), of 20 TeV blazars, all of the HBL class, that have not been previously studied at multiple epochs on the parsec scale. From these 20 sources, we analyze the apparent speeds of 43 jet components that are all detected at four or more epochs. As has been found for other TeV HBLs, the apparent speeds of these components are relatively slow. About two-thirds of the components have an apparent speed that is consistent (within 2σ) with no motion; and some of these components may be stationary patterns whose apparent speed does not relate to the underlying bulk flow speed. In addition, a superluminal tail to the apparent speed distribution of the TeV HBLs is detected for the first time, with eight components in seven sources having a 2σ lower limit on the apparent speed exceeding 1c. We combine the data from these 20 sources with an additional 18 sources from the literature to analyze the complete apparent speed distribution of all 38 TeV HBLs that have been studied with VLBI at multiple epochs. The highest 2σ apparent speed lower limit considering all sources is 3.6c. This suggests that bulk Lorentz factors of up to about 4, but probably not much higher, exist in the parsec-scale radio emitting regions of these sources, consistent with estimates obtained in the radio by other means such as brightness temperatures. This can be reconciled with the high Lorentz factors estimated from the high-energy data if the jet has velocity structures consisting of different emission regions with different Lorentz factors. In particular, we analyze the current apparent speed data for the TeV HBLs in the context of a model with a fast central spine and a slower outer layer.

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Section: Analysis and Discussionmentioning

confidence: 99%

Section: Superluminal Componentsmentioning

confidence: 99%

Section: Superluminal Componentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-epoch VLBA Imaging of 20 New TeV Blazars: Apparent Jet Speeds

Piner

Edwards

2018

ApJ

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“…3 the rolling-up of a helical jet in the quasar 1308+326 (z = 0.997, LSP HPQ). This source is part of the catalog (e.g., Piner et al 2012) of radio reference frame sources of geodetic VLBI (ICRF, Ma et al 1998;Ma et al 2009;Jacobs et al 2014). We investigated and re-modelled the quasar in VLBA archive observations (MOJAVE) to clarify the reason for unusual astrometric position instabilities (e.g., Bouffet, Charlot & Lambert 2012) which could not easily be explained with simple and generally assumed outward motion of jet components.…”

Section: +326: Rolling-up Of a Helixmentioning

confidence: 99%

Rubrik

et al. 2015

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Detailed and long-term VLBI (Very Long Baseline Interferometry) studies of the variable jets of supermassive black holes helps us to understand the emission processes of these fascinating phenomena. When observed and traced precisely, jet component kinematics reveals details about the potential motion of the jet base. Following this motion over decades with VLBI monitoring reveals -in some cases -the signatures of precession. While several processes can cause precession, the most likely cause seems to be a supermassive binary black hole in the central region of the AGN. We present examples of the analysis of high-resolution VLBI observations which provides us with insight into the physics of these objects and reveals evidence for the presence of double black hole cores. EHT (Event Horizon Telescope) observations will probably soon tell us more about the jet origin and launching mechanism at the very centers of nearby active galactic nuclei. An important question to be addressed by the EHT and related observations will be whether Sgr A , the supermassive black hole in the Galactic Center, has a jet as well.

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Relativistic Magnetic Reconnection in Pair Plasmas and Its Astrophysical Applications

Kagan¹,

Sironi²,

Cerutti³

et al. 2016

The Strongest Magnetic Fields in the Universe

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This review discusses the physics of magnetic reconnection -a process in which the magnetic field topology changes and magnetic energy is converted to kinetic energy -in pair plasmas in the relativistic regime. We focus on recent progress in the field driven by theory advances and the maturity of particle-in-cell codes. This work shows that fragmentation instabilities at the current sheet can play a critical role in setting the reconnection speed and affect the resulting particle acceleration, anisotropy, bulk flows, and radiation. Then, we discuss how this novel understanding of relativistic reconnection can be applied to high-energy astrophysical phenomena, with an emphasis on pulsars, pulsar wind nebulae, and active galactic nucleus jets.

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Relativistic Jets in the Radio Reference Frame Image Database. Ii. Blazar Jet Accelerations From the First 10 Years of Data (1994-2003)

Cited by 72 publications

References 50 publications

Multi-epoch VLBA Imaging of 20 New TeV Blazars: Apparent Jet Speeds

Multi-epoch VLBA Imaging of 20 New TeV Blazars: Apparent Jet Speeds

Rubrik

Relativistic Magnetic Reconnection in Pair Plasmas and Its Astrophysical Applications

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