J. L. Richards

MOJAVE. X. PARSEC-SCALE JET ORIENTATION VARIATIONS AND SUPERLUMINAL MOTION IN ACTIVE GALACTIC NUCLEI

We describe the parsec-scale kinematics of 200 active galactic nucleus (AGN) jets based on 15xa0GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2011 May 1. We present new VLBA 15xa0GHz images of these and 59 additional AGNs from the MOJAVE and 2xa0cm Survey programs. Nearly all of the 60 most heavily observed jets show significant changes in their innermost position angle over a 12-16xa0yr interval, ranging from 10° to 150° on the sky, corresponding to intrinsic variations of ~0.°5 to ~2°. The BL Lac jets show smaller variations than quasars. Roughly half of the heavily observed jets show systematic position angle trends with time, and 20 show indications of oscillatory behavior. The time spans of the data sets are too short compared to the fitted periods (5-12xa0yr), however, to reliably establish periodicity. The rapid changes and large jumps in position angle seen in many cases suggest that the superluminal AGN jet features occupy only a portion of the entire jet cross section and may be energized portions of thin instability structures within the jet. We have derived vector proper motions for 887 moving features in 200 jets having at least five VLBA epochs. For 557 well-sampled features, there are sufficient data to additionally study possible accelerations. We find that the moving features are generally non-ballistic, with 70% of the well-sampled features showing either significant accelerations or non-radial motions. Inward motions are rare (2% of all features), are slow (<0.1 mas yr–1), are more prevalent in BL Lac jets, and are typically found within 1 mas of the unresolved core feature. There is a general trend of increasing apparent speed with distance down the jet for both radio galaxies and BL Lac objects. In most jets, the speeds of the features cluster around a characteristic value, yet there is a considerable dispersion in the distribution. Orientation variations within the jet cannot fully account for the dispersion, implying that the features have a range of Lorentz factor and/or pattern speed. Very slow pattern speed features are rare, comprising only 4% of the sample, and are more prevalent in radio galaxy and BL Lac jets. We confirm a previously reported upper envelope to the distribution of speed versus beamed luminosity for moving jet features. Below 1026 W Hz–1 there is a fall-off in maximum speed with decreasing 15xa0GHz radio luminosity. The general shape of the envelope implies that the most intrinsically powerful AGN jets have a wide range of Lorentz factors up to ~40, while intrinsically weak jets are only mildly relativistic.

SBS 0846+513: a new γ-ray-emitting narrow-line Seyfert 1 galaxy

We report Fermi Large Area Telescope (LAT) observations of the radio-loud active galactic nucleus SBS 0846+513 (z = 0.5835), optically classified as a narrow-line Seyfert 1 galaxy, together with new and archival radio-to-X-ray data. The source was not active at γ-ray energies during the first two years of Fermi operation. A significant increase in activity was observed during 2010 October–2011 August. In particular, a strong γ-ray flare was observed in 2011 June reaching an isotropic γ-ray luminosity (0.1–300u2009GeV) of 1.0 × 10^(48)u2009ergu2009s^(−1), comparable to that of the brightest flat spectrum radio quasars, and showing spectral evolution in γ rays. An apparent superluminal velocity of (8.2 ± 1.5)c in the jet was inferred from 2011 to 2012 Very Long Baseline Array (VLBA) images, suggesting the presence of a highly relativistic jet. Both the power released by this object during the flaring activity and the apparent superluminal velocity are strong indications of the presence of a relativistic jet as powerful as those of blazars. In addition, variability and spectral properties in radio and γ-ray bands indicate blazar-like behaviour, suggesting that, except for some distinct optical characteristics, SBS 0846+513 could be considered as a young blazar at the low end of the blazars black hole mass distribution.

Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies

We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio frequencies to X-rays, and supplement these with information available from online catalogs and the literature in order to cover the full electromagnetic spectrum. This is the largest known multiwavelength survey for this type of source. We detected 90% of the sources in X-rays and found 17% at gamma rays. Extreme variability at high energies was also found, down to timescales as short as hours. In some sources, dramatic spectral and flux changes suggest interplay between a relativistic jet and the accretion disk. The estimated masses of the central black holes are in the range

Rapid TeV Gamma-Ray Flaring of BL Lacertae

sim 10^{6-8}M_{odot}

Radio to gamma-ray variability study of blazar S5 0716+714

, smaller than those of blazars, while the accretion luminosities span a range from

MOJAVE XIII. Parsec-Scale AGN Jet Kinematics Analysis Based on 19 years of VLBA Observations at 15 GHz

sim 0.01

Time correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission

to

Radio and γ-ray follow-up of the exceptionally high-activity state of PKS 1510−089 in 2011

sim 0.49

MOJAVE. XII. Acceleration and Collimation of Blazar Jets on Parsec Scales

times the Eddington limit, similar to those of quasars. The distribution of the calculated jet power spans a range from

Studies of the Jet in Bl Lacertae. I .Recollimation Shock and Moving Emission Features

sim 10^{42.6}