13-15 December 2017
MPI für Radioastronomie
Europe/Berlin timezone
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Contribution List

Displaying 31 contributions out of 31
Session: Open Session I
The observational program of RadioAstron allows for a limited number of imaging experiments that can be performed in the "perigee imaging" mode and sometimes amended by "long baseline segments" which are organized as separate observing runs. Most of the RadioAstorn imaging experiments have been done within the framework of three key science programs (KSP) focusing on different aspects of phyics of ... More
Presented by Dr. Andrei LOBANOV
Session: Open Session II
A summary of the scientific results from the Polarisation Key Science Program will be presented
Presented by Dr. Jose L. GÓMEZ on 13 Dec 2017 at 10:45
A status report of the polarisation KSP and the plans for the data reduction and publication will be presented and discussed with the participants. The planning of projects for the AO-6 will also be addressed.
Presented by Dr. Jose L. GÓMEZ on 14 Dec 2017 at 11:45
Session: Open Session III
Several intriguing results were delivered by space and ground observations of 3C 273. First, the shuttle movement of the apparent core at 7 mm was discovered. A self-referencing method was used to show that two independent regions in the jet of 3C 273 accelerated/decelerated simultaneously which can only be ascribed to the movement of the apparent core by 4.4 pc, deprojected, in 5 months. It was ... More
Presented by Mr. Mikhail LISAKOV on 13 Dec 2017 at 13:50
Session: Open Session IV
We present measurements of the core shift effect for a large sample of quasars and its significant variability. Typical magnitudes of core shift between 2 and 8 GHz bands is about 0.5 mas with variability amplitude of several tenths of a mas. A strong dependence between core flux and position is detected which suggests certain models of how flares happen. This relationship also allows deducing the ... More
Presented by Mr. Alexander PLAVIN on 13 Dec 2017 at 17:00
We are going to present a status report of the correlation of RadioAstron projects that is carried out at the MPIfR correlator. Experiments observed within the AO-1 and AO-2 periods are all correlated and released. We are now correlating and re-correlating experiments observed within the AO-3 and AO-4 projects and we are also receiving the data from the experiments within AO-5.
Presented by Rebecca AZULAY ROMERO on 14 Dec 2017 at 09:30
We report on the technical details and the status of VLBI data transfers from the MPIfR correlator to ASC.
Presented by Jan WAGNER on 14 Dec 2017 at 09:50
Session: Open Session IV
We are undertaking a 6cm flux monitoring program to study the variability properties of a sample of RadioAstron blazars. The monitoring offers an independent probe of the innermost structure of AGN cores on micro-arcsecond angular scales which will be compared with direct Space VLBI measurements. Moreover, the focusing and defocusing effects of ISS, if confirmed by the ground-based observations, m ... More
Presented by Jun LIU on 13 Dec 2017 at 16:40
Session: Open Session IV
Presented by Prof. Matt LISTER on 13 Dec 2017 at 15:40
Presented by Tuomas SAVOLAINEN on 14 Dec 2017 at 13:30
Presented by Dr. Yuri KOVALEV on 14 Dec 2017 at 11:00
Presented by Andrei LOBANOV on 14 Dec 2017 at 14:15
Session: Open Session III
Astrophysical jets are considered among the most powerful and variable known objects in the universe. VLBI observations provide us ultra-high resolution images which can reveal the innermost structural dynamics of the jet. This knowledge in a combination with the gamma-ray variability of a source gives us the unique opportunity to localize the gamma-ray emission as well as to estimate its distance ... More
Presented by Ms. Efthalia TRAIANOU on 13 Dec 2017 at 14:50
Session: Open Session IV
M87 is one of the two main targets of the Event Horizon Telescope (EHT) project since it migth allow to detect the black hole shadow and promises a direct view on the jet launching process itself. In this talk, we present a re-analysis of 31 VLBA observations at 15 GHz (MOJAVE program). One of the findings is, that the M87-jet visible at 15 GHz, probes a different physical zone compared to the sta ... More
Presented by Dr. Silke BRITZEN on 13 Dec 2017 at 17:20
Session: Lunch Kolloquium
In this talk I will present the current status of the Space VLBI mission as well as recent results of RadioAstron studies of AGNs, pulsars, masers, interstellar medium as well as gravitational redshift experiment.
Presented by Dr. Yuri KOVALEV
Recent RadioAstron discoveries made for 3C 273 and 0529+483 at 18 cm have brought the refractive scattering substructure in AGN to the scene. The refractive noise mimics the true emission of the jet, thus spoiling brightness temperature estimates. To account for the substructure one needs to get the properties of the scattering material on the spatial scales of several AU, which became available o ... More
Presented by Mr. Mikhail LISAKOV on 14 Dec 2017 at 16:00
Session: Open Session I
The Space-VLB interferometer RadioAstron has performed a survey of 248 radio-loud AGNs at 18, 6, and 1.3 cm at projected spacings up to 350,000 km. Significant detections at space-ground baselines were achieved for 164 of them. Many quasars are found to be much brighter than expected breaking the inverse-Compton limit. Moreover, it was found that the fraction of linearly polarized correlated flux ... More
Presented by Dr. Yuri KOVALEV on 13 Dec 2017 at 09:00
Presented by Dr. Yuri KOVALEV on 14 Dec 2017 at 09:00
Session: Open Session I
Near-perigee imaging observations of nearby radio galaxies with RadioAstron space-VLBI telescope allow us to probe the jet formation region of AGN at unprecedented resolution. RadioAstron images of radio galaxy 3C84 at the center of the Perseus cluster have revealed a strong collimation of its edge-brightened jet at 300 to 400 Schwarzschild radii (r_s) from the black hole and an almost cylindric ... More
Presented by Dr. Tuomas SAVOLAINEN on 13 Dec 2017 at 09:30
Session: Open Session II
The RadioAstron active galactic nuclei (AGN) polarization Key Science Project (KSP) aims at exploiting the unprecedented angular resolution provided by RadioAstron to study jet launching/collimation and magnetic-field configuration in AGN jets. The targets of our KSP are some of the most powerful blazars in the sky. We present observations at 22 GHz of 3C 273, performed in 2014, designed to rea ... More
Presented by Dr. Gabriele BRUNI on 13 Dec 2017 at 11:35
Session: Open Session IV
We present 15 GHz stacked VLBA images of 373 jets associated with active galactic nuclei (AGN) having at least five observing epochs within a 20 yr time interval 1994-2015 from the MOJAVE programme and/or its precursor, the 2 cm VLBA Survey. These data are supplemented by 1.4 GHz single-epoch VLBA observations of 135 MOJAVE AGNs to probe larger scale jet structures. The typical jet geometry is ... More
Presented by Dr. Alexander PUSHKAREV on 13 Dec 2017 at 16:20
Session: Open Session III
Synchrotron radiation from AGN jets can be linearly polarized up to ∼70% in theory. However, the observed degree of linear polarization is usually much lower. The weak linear polarization could to be due to (i) highly tangled magnetic fields in turbulent plasma, (ii) strong Faraday rotation and (iii) blending of polarized sub-components within the beam. The bright radio-galaxy 3C 84 (Perseu ... More
Presented by Mr. Jae-Young KIM on 13 Dec 2017 at 14:10
Session: Open Session I
I will present the RadioAstron Key Science Project on strong AGN. The goal of the project is to obtain extremely high-resolution images of the jets of several well-known, bright AGN, and investigate the sub-pc scale jet structure at multiple frequencies. The sources included in the KSP are S5 0836+710, 3C 273, 3C 345 and 1642+690. I will describe the KSP, and present preliminary results on th ... More
Presented by Ms. Laura VEGA GARCÍA on 13 Dec 2017 at 10:00
Presented by Dr. Michael J. JOHNSON on 14 Dec 2017 at 16:20
Presented by Eduardo ROS on 14 Dec 2017 at 16:40
Session: Open Session II
We will present the first results of fine-scale polarized imaging of BL Lac object S5 0716+714. Observations have been performed at 22 GHz with a ground-space VLBI array including RadioAstron at the projected baselines of 4-6~Earth's diameters in length. Some of the correlation peculiarities of RadioAstron data will be highlighted.
Presented by Dr. Evgeniya V. KRAVCHENKO on 13 Dec 2017 at 11:15
Session: Open Session III
The high brightness temperatures, $T_\mathrm{b} \geq 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux densit ... More
Presented by Dr. Sergey PILIPENKO on 13 Dec 2017 at 14:30
We would like to discuss some correlation and calibration issues of the RadioAstron data, arose from reduction of the S5 0716+714 imaging experiment.
Presented by Dr. Evgeniya V. KRAVCHENKO on 14 Dec 2017 at 10:10
Session: Open Session IV
We present relativistic magnetohydrodynamic (RMHD) simulations of stationary overpressured magnetized relativistic jets which are characterized by their dominant type of energy, namely internal, kinetic, or magnetic. Each model is threaded by a helical magnetic field with a pitch angle of $45^\circ$ and features a series of recollimation shocks produced by the initial pressure mismatch, and whose ... More
Presented by Mr. Antonio FUENTES on 13 Dec 2017 at 16:00
Session: Open Session I
Presented by Anton ZENSUS on 13 Dec 2017 at 08:50