Aims. We have investigated the differences in apparent opening angles between the parsec-scale jets of the active galactic nuclei (AGN) detected by the Fermi Large Area Telescope during its first ...three months of operations and those of non-LAT-detected AGN. Methods. We used 15.4 GHz VLBA observations of sources from the 2 cm VLBA MOJAVE program, a subset of which comprises the statistically complete flux density limited MOJAVE sample. We determined the apparent opening angles by analyzing transverse jet profiles from the data in the image plane and by applying a model fitting technique to the data in the $(u,v)$ plane. Both methods provided comparable opening angle estimates. Results. The apparent opening angles of γ-ray bright blazars are preferentially larger than those of γ-ray weak sources. At the same time, we have found the two groups to have similar intrinsic opening angle distributions, based on a smaller subset of sources. This suggests that the jets in γ-ray bright AGN are oriented at preferentially smaller angles to the line of sight resulting in a stronger relativistic beaming. The intrinsic jet opening angle and the bulk flow Lorentz factor are found to be inversely proportional, as predicted by standard models of compact relativistic jets. If a gas dynamical jet acceleration model is assumed, the ratio of the initial pressure of the plasma in the core region P0 to the external pressure $P_{\mathrm{ext}}$ lies within the range 1.1 to 34.6, with a best fit estimate of $P_0/P_\mathrm{ext}\approx 2$.
ABSTRACT We study the kinematics of ridge lines on the parsec-scale jet of the active galactic nucleus BL Lacertae. We show that the ridge lines display transverse patterns that move superluminally ...downstream, and that the moving patterns are analogous to waves on a whip. Their apparent speeds βapp (units of c) range from 3.9 to 13.5, corresponding to in the galaxy frame. We show that the magnetic field in the jet is well ordered with a strong transverse component, and assume that it is helical and that the transverse patterns are Alfvén waves propagating downstream on the longitudinal component of the magnetic field. The wave-induced transverse speed of the jet is non-relativistic ( ). In 2010 the wave activity subsided and the jet then displayed a mild wiggle that had a complex oscillatory behavior. The Alfvén waves appear to be excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking the handle. A simple model of the system with plasma sound speed βs = 0.3 and apparent speed of a slow MHD wave βapp, S = 4 yields Lorentz factor of the beam Γbeam ∼ 4.5, pitch angle of the helix (in the beam frame) ∼ 67°, Alfvén speed βA ∼ 0.64, and magnetosonic Mach number Mms ∼ 4.7. This describes a plasma in which the magnetic field is dominant and in a rather tight helix, and Alfvén waves are responsible for the moving transverse patterns.
Herein we report the optimization of a series of tricyclic indazoles as selective estrogen receptor degraders (SERD) and antagonists for the treatment of ER+ breast cancer. Structure based design ...together with systematic investigation of each region of the molecular architecture led to the identification of N-1-(3-fluoropropyl)azetidin-3-yl-6-(6S,8R)-8-methyl-7-(2,2,2-trifluoroethyl)-6,7,8,9-tetrahydro-3H-pyrazolo4,3-fisoquinolin-6-ylpyridin-3-amine (28). This compound was demonstrated to be a highly potent SERD that showed a pharmacological profile comparable to fulvestrant in its ability to degrade ERα in both MCF-7 and CAMA-1 cell lines. A stringent control of lipophilicity ensured that 28 had favorable physicochemical and preclinical pharmacokinetic properties for oral administration. This, combined with demonstration of potent in vivo activity in mouse xenograft models, resulted in progression of this compound, also known as AZD9833, into clinical trials.
We report on the acceleration properties of 329 features in 95 blazar jets from the MOJAVE Very Long Baseline Array program. Nearly half the features and three-quarters of the jets show significant ...changes in speed and/or direction. In general, apparent speed changes are distinctly larger than changes in direction, indicating that changes in the Lorentz factors of jet features dominate the observed speed changes rather than bends along the line of sight. Observed accelerations tend to increase the speed of features near the jet base, <, ~10-20 pc projected, and decrease their speed at longer distances. The range of apparent speeds at a fixed distance in an individual jet can span a factor of a few, indicating that shock properties and geometry may influence the apparent motions; however, we suggest that the broad trend of jet features increasing their speed near the origin is due to an overall acceleration of the jet flow out to deprojected distances of the order of 10 super(2) pc, beyond which the flow begins to decelerate or remains nearly constant in speed. We estimate intrinsic rates of change of the Lorentz factors in the galaxy frame of the order of Gamma/Gamma Asymptotically = to 10 super(-3) to 10 super(-2) yr super(-1), which can lead to total Lorentz factor changes of a factor of a few on the length scales observed here. Finally, we also find evidence for jet collimation at projected distances of <, ~10 pc in the form of the non-radial motion and bending accelerations that tend to better align features with the inner jet.
We have carried out a Chandra X-ray and multifrequency radio Very Long Baseline Array study of the active galactic nucleus (AGN) TXS 0128+554, which is associated with the Fermi γ-ray source 4FGL ...J0131.2+5547. The AGN is unresolved in a target 19.3 ks Chandra image, and its spectrum is well fit by a simple absorbed power-law model, with no distinguishable spectral features. Its relatively soft X-ray spectrum compared to other compact symmetric objects (CSOs) may be indicative of a thermal emission component, for which we were able to obtain an upper temperature limit of kT = 0.08 keV. The compact radio morphology and measured advance speed of 0.32 c 0.07 c indicate a kinematic age of only 82 yr 17 yr, placing TXS 0128+554 among the youngest members of the CSO class. The lack of compact, inverted spectrum hotspots and an emission gap between the bright inner jet and outer radio lobe structure indicate that the jets have undergone episodic activity, and were relaunched a decade ago. The predicted γ-ray emission from the lobes, based on an inverse Compton-emitting cocoon model, is three orders of magnitude below the observed Fermi-LAT flux. A comparison to other Fermi-detected and non-Fermi-detected CSOs with redshift z < 0.1 indicates that the γ-ray emission likely originates in the inner jet/core region, and that nearby, recently launched AGN jets are primary candidates for detection by the Fermi-LAT instrument.
We present the first results of a radio survey of 79 narrow-line Seyfert 1 (NLS1) carried out with the Karl G. Jansky Very Large Array (JVLA) at 5 GHz in A configuration aimed at studying the radio ...properties of these sources. We report the detection of extended emission in one object: Mrk 783. This is intriguing, since the radio-loudness parameter R of this object is close to the threshold between radio-quiet and radio-loud active galactic nuclei (AGN). The galaxy is one of the few NLS1 showing such an extended emission at z < 0.1. The radio emission is divided into a compact core component and an extended component, observed on both sides of the nucleus and extending from 14 kpc southeast to 12 kpc northwest. There is no sign of a collimated jet and the shape of the extended component is similar to those of some Seyfert galaxies. The properties of the emission are compatible with a relic produced by the intermittent activity cycle of the AGN.
We report first-epoch circular polarization results for 133 active galactic nuclei in the MOJAVE program to monitor the structure and polarization of a flux-limited sample of extragalactic radio jets ...with the VLBA at 15 GHz. We found strong circular polarization (>=0.3%) in approximately 15% of our sample. The circular polarization was usually associated with jet cores; however, we did find a few strong jet components to be circularly polarized. The levels of circular polarization were typically in the range of 0.3%-0.5% of the local Stokes I value. We found no strong correlations between fractional circular polarization of jet cores and source type, redshift, EGRET detections, linear polarization, or other observed parsec-scale jet properties. There were differences between the circular-to-linear polarization ratios of two nearby galaxies versus more distant quasars and BL Lac objects. We suggest this is because the more distant sources have either (1) less depolarization of their linear polarization, and/or (2) poorer effective linear resolution, and therefore, their VLBA cores apparently contain a larger amount of linearly polarized jet emission. The jet of 3C 84 shows a complex circular polarization structure, similar to observations by Homan & Wardle 5 years earlier; however, much of the circular polarization seems to have moved, consistent with a proper motion of 0.06c. The jet of 3C 273 also has several circularly polarized components, and we find that their fractional circular polarization decreases with distance from the core.
We report on a multiwavelength campaign for the radio-loud narrow-line Seyfert 1 (NLS1) galaxy PMNJ0948+0022 (z= 0.5846) performed in 2010 July-September and triggered by a high-energy γ-ray outburst ...observed by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope. The peak flux in the 0.1-100 GeV energy band exceeded, for the first time in this type of source, the value of 10-6 photon cm-2s-1, corresponding to an observed luminosity of 1048ergs-1. Although the source was too close to the Sun position to organize a densely sampled follow-up, it was possible to gather some multiwavelength data that confirmed the state of high activity across the sampled electromagnetic spectrum. The comparison of the spectral energy distribution of the NLS1 PMNJ0948+0022 with that of a typical blazar - such as 3C273 - shows that the power emitted at γ-rays is extreme. PUBLICATION ABSTRACT
We have compared the radio emission from a sample of parsec-scale active galactic nucleus (AGN) jets as measured by the VLBA at 15 GHz, with their associated g-ray properties that are reported in the ...Fermi Large Area Telescope (LAT) three month bright source list. We find in our radio-selected sample that the g-ray photon flux correlates well with the quasi-simultaneously measured compact radio flux density. The LAT-detected jets in our radio-selected complete sample generally have higher compact radio flux densities, and their parsec-scale cores are brighter (i.e., have higher brightness temperature) than the jets in the LAT nondetected objects. This suggests that the jets of bright g-ray AGN have preferentially higher Doppler-boosting factors. In addition, AGN jets tend to be found in a more active radio state within several months from LAT-detection of their strong g-ray emission. This result becomes more pronounced for confirmed g-ray flaring sources. We identify the parsec-scale radio core as a likely location for both the g-ray and radio flares, which appear within typical timescales of up to a few months of each other.
ABSTRACT
Within the MOJAVE VLBA programme (Monitoring of Jets in AGN with VLBA Experiments), we have accumulated observational data at 15 GHz for hundreds of jets in gamma-ray bright active galactic ...nuclei since the beginning of the Fermi scientific observations in 2008 August. We investigated a time delay between the flux density of AGN parsec-scale radio emission at 15 GHz and 0.1–300 GeV Fermi LAT photon flux, taken from constructed light curves using weekly and adaptive binning. The correlation analysis shows that radio is lagging gamma-ray radiation by up to 8 months in the observer’s frame, while in the source frame, the typical delay is about 2–3 months. If the jet radio emission, excluding the opaque core, is considered, significant correlation is found at greater time lags. We supplement these results with VLBI kinematics and core shift data to conclude that the dominant high-energy production zone is typically located at a distance of several parsecs from the central nucleus. We also found that quasars have on average more significant correlation peak, more distant gamma-ray emission region from the central engine and shorter variability time-scale compared to those of BL Lacertae objects.
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