# Dissecting the Universe - Workshop on Results from High-Resolution VLBI

from 30 November 2015 to 2 December 2015
Europe/Berlin timezone
Home > Contribution List

## Contribution List

Displaying 55 contributions out of 55
Type: Contributed Session: Session III - mm-VLBI: AGN at 3mm
Abstract: Very Long Baseline Interferometry (VLBI) Observations at 86 GHz reach a resolution of about 50 microarcseconds and sample the scales as small as 10^3 - 10^4 Schwartzchild radii of the central black hole in Active Galactic Nuclei (AGN), and uncover the jet regions where accelaration and collimation of the relativistic flow takes place. Synchrotron radiation becomes optically thin at mill ... More
Presented by Ms. Dhanya G NAIR on 1 Dec 2015 at 10:15
The stellar binary system LS I +61°303 consists of a Be star and a compact object (neutron star or black hole) in an eccentric orbit. Several authors predict periodic accretion with two peaks along such an eccentric orbit. Indeed, the orbital period of P1 = 26.4960±0.0028 days has been found in the emission from the source at different wavelengths, but timing analysis of radio data, peaking only ... More
Presented by Mr. Frederic JARON on 2 Dec 2015 at 12:43
Astro Space Locator (ASL) software package is focused on post-correlation analysis of the data obtained by the aperture synthesis method with Very Long Baseline Interferometry (VLBI including Space-VLBI). The VLBI method of aperture synthesis is based on the visibility function measurements by separated telescopes. ASL allows the user to perform the operation fringe synthesis and averaging (eva ... More
Presented by Mr. Victor ZUGA on 2 Dec 2015 at 12:40
Determining relative shift between VLBI maps on different frequencies is the typical task arising in spectral index and core shift measurements. This shift can be found using a 2D cross-correlation of the maps with optically thick regions excluded. However the masking procedure is still performed manually, which can lead to uncertainties due to human driven choice that dominate in the total error ... More
Presented by Mr. Mikhail LISAKOV, Dr. Ilya PASHCHENKO on 2 Dec 2015 at 12:28
Significant progress in millimeter VLBI has recently been made with the Event Horizon Telescope project, which aims to resolve strong field General Relativistic (GR) signatures in nearby supermassive black holes (in particular Sgr A$^\star$ and M$\,$87). Adding APEX to the inner American array now allows to image the Galactic center (Sgr A$^\star$) with a resolution of $\sim$3 Schwarzschild radii ... More
Presented by Dr. Rusen LU on 1 Dec 2015 at 14:20
Reliable estimates of the uncertainties of VLBI results are essential for quantifying their significance. We propose to use the bootstrap for obtaining such estimates. This well known and widely used method handles spatial correlation in image domain and accounts for nonuniformity and non gaussian nature of visibility noise on different baselines in uv-domain. The resulting estimates depend on qua ... More
Presented by Dr. Ilya PASHCHENKO on 2 Dec 2015 at 12:34
Located at the dynamical center of our Galaxy, the black hole candidate Sagittarius A$^\star$ (Sgr A$^\star$) is an ideal target for studying the structure, emission, and dynamics close to an event horizon with high-resolution VLBI. We present the first results of 3mm observations of Sgr A$^\star$ and NRAO$\,$530 performed with the VLBA, GBT and LMT on May 2015. Thanks to an unprecedented sensiti ... More
Presented by Dr. Cornelia MUELLER on 1 Dec 2015 at 14:40
In late 2009 quasar 3C273 experienced a series of strong gamma-ray flares which triggered our 6 cm - 7 mm VLBA follow up observations. We added to our 4 multifrequency epochs four years of 7 mm data in order to trace kinematics of newborn components. The connection between gamma-ray and mm-wavelength variability is complex in 3C273 and there is no one-to-one correspondence in the lightcurves. I ... More
Presented by Mr. Mikhail LISAKOV on 2 Dec 2015 at 09:15
Type: Contributed Session: Session I - RadioAstron
Millimetron is a planned 10-meter class space telescope for the far infrared to millimeter wavelengths (approx. 20 microns to 1 cm). It will operate in two modes. First one, the single dish mode, will cover wavelengths which are poorly accessible from the Earth's surface. With its high sensitivity reached due to active cooling of the telescope mirrors, Millimetron in this mode will observe interst ... More
Presented by Dr. Sergey PILIPENKO on 30 Nov 2015 at 13:30
Magnetic fields play central roles in the accretion, emission, and outflow near black holes but have never been directly observed in this region. Because linear polarization of the bright synchrotron emission from galactic cores traces these magnetic fields, polarimetric interferometry with the Event Horizon Telescope (EHT) is capable of imaging the near-horizon fields. I will present the results ... More
Presented by Dr. Michael JOHNSON on 1 Dec 2015 at 15:00
The problems of implementation and operation of the Data Processing Center for the Radioastron Project as well as the problem of implementation of the Data Center for Millimetron project are considered. The main features of these SVLBI projects are large flow of information, big volume of data and computing power. The solving of this problems is organization of Data Processing Center or Data Cen ... More
Presented by Dr. Marina SHATSKAYA on 2 Dec 2015 at 12:05
Type: Contributed Session: Refreshments and Discussion
Discussion.
Presented by Prof. Eduardo ROS, Dr. Andrei P. LOBANOV, Dr. Yuri KOVALEV, Dr. Talvikki HOVATTA, Dr. Marcello GIROLETTI, Prof. J. Anton ZENSUS on 1 Dec 2015 at 20:25
Type: Contributed Session: Session VI - RadioAstron: AGN and beyond
RadioAstron offers a unique opportunity to study the nuclear structure in nearby AGN with a spatial resolution of a few hundreds of Schwarzschild radii, allowing to probe the region of jet acceleration and collimation. We carried out perigee imaging of the nearby TeV BL Lac Markarian 501 at 6, and 1.3 cm, aiming to study in detail this BL Lac source and its peculiar jet. In this paper, we first re ... More
Presented by Dr. Marcello GIROLETTI on 1 Dec 2015 at 16:30
Type: Contributed Session: Session IX - mm-VLBI and the KVN
Thanks to high-angular resolution by mm-VLBI observations, now we can observe the relativistic jets up to the very vicinity of jet formation site in the black hole accretion disk system. In this presentation, I will review and summarize the dynamics in acceleration and collimation regions of relativistic jets in black hole accretion disk system from theoretical and numerical point of view. Fir ... More
Presented by Dr. Yosuke MIZUNO on 2 Dec 2015 at 15:00
The high radio frequency polarization imaging of non-thermal emission from AGN is a direct way to probe the magnetic field strength and structure in the immediate vicinity of SMBHs and is crucial in testing the jet-launching scenario. To explore the the magnetic field configuration at the base of jets in blazars, I took advantage of the full polarization capabilities of the GMVA (Global Millimeter ... More
Presented by Dr. Bindu RANI on 2 Dec 2015 at 16:30
Present developments in radio interferometry with spaceborne antennas and at millimetre wavelengths drive the field of study into a truly unexplored domain of baseline lengths and fringe spacings. The ongoing VLBI efforts at 1 mm have pushed this limit to ~8 Gigalambdas, and RadioAstron measurements have reached up to ~15 Gigalambdas, which signifies more than a factor of four increase of the fri ... More
Presented by Dr. Andrei P. LOBANOV on 1 Dec 2015 at 11:05
High resolution VLBI observations of relativistic jets are essential to constrain fundamental parameters of current jet formation models. At a distance of 249 Mpc, Cygnus A is a unique target for such studies, being the only powerful FRII radiogalaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing at millimeter wavelengths unveils th ... More
Presented by Dr. Biagina BOCCARDI on 30 Nov 2015 at 16:55
We will report results of GMVA observation of M 87 and progress of the Greenland Telescope Project. In order to investigate the innermost region of the M 87, we conducted GMVA observation in 2014. We revealed double ridge structure as is observed by VLBI at low frequency observations. The measured streamline is reasonably agreed with the previous observations at low frequency. We will disc ... More
Presented by Dr. Keiichi ASADA on 30 Nov 2015 at 15:35
Type: Contributed Session: Session IX - mm-VLBI and the KVN
Relativistic outflows in AGNs are ultimately powered by gravitational energy conversion by super-massive black holes. Recent mm-VLBI observations reveal in an increasing number of objects a misalignment of the jet position angles between innermost and outer jet regions. A combination of the 3 antennas of the Korean VLBI Network (KVN) with the Global 3-mm VLBI Array (GMVA) enhances the uv-coverage ... More
Presented by Dr. Shoko KOYAMA on 2 Dec 2015 at 14:20
A unique test of general relativity is possible with the space radio telescope RadioAstron. The ultra-stable on-board hydrogen maser frequency standard and the highly eccentric orbit make RadioAstron an ideal instrument for probing the gravitational redshift effect. The large gravitational potential variation, occurring on the time scale of $\sim$24 hr, causes a large varia-tion of the on-board H- ... More
Presented by Prof. Valentin RUDENKO, Dr. Dmitry LITVINOV on 1 Dec 2015 at 17:40
Recent space VLBI observations with Radioastron have allowed us to image the jet in the quasar 0836+710 with great detail. The combination of these results with previous space and gound VLBI observations show a very detailed picture of the jet structure. It confirms the interpretation of the visible radio-jet as high-pressure regions with higher emissivity at GHz frequencies within a wider flow. T ... More
Presented by Dr. Manel PERUCHO on 1 Dec 2015 at 12:15
Here we provide a brief over view of the role of JIVE in the BlackHoleCam project. Our efforts in developing software that will open up the field of millimeter VLBI for astronomers outside of the radio community and simplify operations and verification checks at the telescopes are described.
Presented by Dr. Ilse VAN BEMMEL on 1 Dec 2015 at 15:25
Detailed studies of the jet-accretion disk connection are essential for a better understanding of the formation and launch of the jets. Water disk masers in the very central region of active galaxies, with the circumnuclear disk being viewed edge-on, provide a unique sample of targets for studying the accretion disk surrounding the super massive black holes. In this work we investigate the accret ... More
Presented by Ms. Fateme KAMALI on 2 Dec 2015 at 10:15
M87, possibly the most studied relativistic jet in active radio galaxies, has been spatially resolved from ten to tens of millions of Schwarzschild radii; it gives a unique opportunity for understanding an AGN jet from birth to termination. Several key issues in AGN jets can be extensively discussed based on multi-frequency radio observations and magnetohydrodynamic (MHD) jet theories toward M87. ... More
Presented by Dr. Masanori NAKAMURA on 30 Nov 2015 at 15:55
Type: Contributed Session: Session III - mm-VLBI: AGN at 3mm
The Boston University group have being monitored the parsec scale jet of the quasar 3C454.3 with the Very Long Baseline Array at 43 GHz since 1995 January. Thusfar, we have collected 128 total and polarized intensity images of the quasar with a high resolution of ~0.1 mas. I will discuss VLBI properties of the two prominent features in the innermost jet of 3C454.3, the VLBI core and quasi-stationa ... More
Presented by Dr. Svetlana JORSTAD on 1 Dec 2015 at 09:55
The nearby twin-jet system in the low-luminosity active nucleus of NGC 1052 is an ideal target for mm-VLBI studies of jet formation on the smallest accessible scales. At cm-wavelength, NGC 1052 is well known for its prominent emission gap between the two jets, that is caused by free-free absorption in a circumnuclear torus. GMVA observations taken in October 2004 peer through the absorber, reveali ... More
Presented by Ms. Anne-Kathrin BACZKO on 30 Nov 2015 at 16:15
Type: Invited Session: Session III - mm-VLBI: AGN at 3mm
Millimeter-wave VLBI is the only technique that directly images the relativistic jets of blazars. The author will present and discuss recent results of monitoring of gamma-ray bright blazars with the VLBA (VLBA-BU-BLAZAR program) and GMVA, as well as prospects for 1 mm VLBI. Polarization and relative timing of events at higher frequencies with changes in polarization and structure at millimeter wa ... More
Presented by Prof. Alan MARSCHER on 1 Dec 2015 at 09:00
Space VLBI observations with RadioAstron provide an extraordinary improvement of angular resolution. In this talk, I will present the results obtained from RadioAstron imaging of the quasar 0836+710 at L, C, and K bands. The images of 0836+710 show a wealth of structure on scales ranging from 0.2 to 150 milliarcseconds, which enables detailed studies of shocks and plasma instability development in ... More
Presented by Ms. Laura VEGA GARCÍA on 1 Dec 2015 at 11:55
The Event Horizon Telescope Collaboration is developing a very sensitive VLBI array for the millimeter and submillimeter wavelength regime. Its primary targets are the supermassive black holes in M87 and Sagittarius A*, for which it is already achieving an angular resolution finer than the diameter of the lensed photon ring predicted by general relativitiy. The EHT has also collected data over s ... More
Presented by Dr. Vincent FISH on 1 Dec 2015 at 14:00
Despite numerous and detailed studies of the jets of Active Galactic Nuclei (AGN) on pc-scales, many questions are still debated. The physical nature of the jet-components is one of the most prominent unsolved problems as is the launching mechanism of jets in AGN. An in-depth investigation of long-term archival VLBI and multi-wavelength data (several decades) in combination with the application of ... More
Presented by Dr. Silke BRITZEN on 2 Dec 2015 at 17:10
Polarisation studies using mm-VLBI probe the intrinsic linear polarization of relativistic outflows at sub-parsec scales, how uniform is the magnetic field geometry and how does it evolve with time, as well as the presence of recollimation shocks near the core region, and structural changes at the innermost jet. We present preliminary results of the first GMVA observations of highly variable, pol ... More
Presented by Prof. Eduardo ROS on 2 Dec 2015 at 09:00
The “Radioastron” space mission is the unique project of Russian Space Agency (Roscosmos) and Russian Academy of Sciences to investigate the Universe by means VLBI principles implementation with “Spektr-R” space satellite. “Spektr-R” onboard 10-m radio telescope has been operating since 15 November, 2011 as the Space element of the space-ground interferometer at the orbit with its apog ... More
Presented by Dr. Alexey RUDNITSKIY on 2 Dec 2015 at 12:25
We present polarimetric 1.3 cm RadioAstron, 7 mm VLBA, and 3 mm GMVA observations of a sample of blazars probing the innermost jet regions at tens of microarcseconds angular resolution. Comparison of the total and polarized emission across these wavebands allows to determine the magnetic field structure and strength in the vicinity of the central black hole through Faraday rotation analysis. It al ... More
Presented by Dr. Jose L. GÓMEZ on 1 Dec 2015 at 16:00
Type: Invited Session: Session I - RadioAstron
On behalf of the Radioastron pulsar group this report presents an overview of the studies which were done with the Radioastron space radio telescope during the first four years of mission operation, including the early and key science programs. Space-VLBI observations of pulsars with the highest angular resolution revealed the new interstellar plasma scattering effects, such as, resolving the subs ... More
Presented by Mr. Alexey RUDNITSKIY on 30 Nov 2015 at 14:10
Quasar 0529+483 is one of 28 extragalactic sources detected on projected baselines longer than 200 000 km at 4.8 and 1.7 GHz with ground-space interferometer RadioAstron as a part of the AGN survey program. Its correlated flux density at the longest baselines was found to be a few percent of the peak flux density and cannot be explained by a simple single Gaussian model which fits the data at shor ... More
Presented by Dr. Sergey PILIPENKO on 2 Dec 2015 at 12:31
We present results of multifrequency high resolution Very Long Baseline Interferometry (VLBI) observations of the nearby radio galaxy 3C 84. This object is one of the closest and thus best-studied misaligned active galactic nuclei. Despite gamma-ray silent during the EGRET-era, 3C84 has been detected during high-energy flares by Fermi and MAGIC telescopes. Recent high-resolution observations point ... More
Presented by Dr. Monica ORIENTI on 1 Dec 2015 at 17:20
The largest key science program of the RadioAstron mission is the survey of strong active galactic nuclei (AGN) at the highest angular resolution. The main goal of the survey is to study physics of AGN cores by observing AGN up to the longest RadioAstron projected baselines and measuring the geometries and brightness temperatures of the cores. To date AGN emission is successfully detected from abo ... More
Presented by Mr. Petr VOYTSIK on 2 Dec 2015 at 12:37
Type: Invited Session: Session I - RadioAstron
The RadioAstron Space VLBI mission utilizes the 10-m radio telescope on board the dedicated Spektr-R spacecraft to observe cosmic radio sources with an unprecedented angular resolution at 92, 18, 6 and 1.3 cm. The longest baseline of the space-ground interferometer is about 350,000 km. We will review in the talk basic parameters and capabilities of the space radio telescope Spektr-R and RadioAstro ... More
Presented by Dr. Yuri KOVALEV on 30 Nov 2015 at 13:10
The RadioAstron AGN survey is performed by the space radio telescope Spektr-R and many sensitive ground radio telescopes in Russia, Europe, Asia, USA, South Africa, Australia, Japan at 18, 6, and 1.3 cm and has already detected about 140 AGNs at projected spacings up to 27 Earth diameters. Formal resolution as high as 14 microarcsec has been achieved for AGNs observed at 22 GHz. Current status and ... More
Presented by Dr. Yuri KOVALEV on 1 Dec 2015 at 11:25
We used 15 GHz VLBA observations of 373 sources having at least 5 epochs within a 20-yr time interval 1994–2015 from the MOJAVE program and/or its predecessor, the 2 cm VLBA Survey. For each source we produced a corresponding stacked image averaging all available epochs for a better reconstruction of the cross section of the flow. We have analyzed jet profiles transverse to the local jet ridge l ... More
Presented by Dr. Alexander PUSHKAREV on 2 Dec 2015 at 16:10
Observations of the masers in the course of RadioAstron mission yielded detections of fringes for a number of sources in both water and hydroxyl maser transitions. Some sources display numerous ultra-compact details. This proves that implementation of the space VLBI technique for maser studies is possible technically and is not always prevented by the interstellar scattering, maser beaming and oth ... More
Presented by Dr. Andrej M. SOBOLEV on 2 Dec 2015 at 10:55
At radio wavelengths, scattering in the interstellar medium distorts the appearance of astronomical sources. When averaged over a sufficiently long time, the scattering results in a blurred image of the source. However, the scattering has the opposite effect for individual observing epochs, introducing substructure in the image. Also, unlike angular and temporal broadening, which become weaker at ... More
Presented by Dr. Michael JOHNSON on 2 Dec 2015 at 15:50
I will describe the Global Millimetre VLBI Array and I will introduce major technical advancements in progress.
Presented by Dr. Thomas P. KRICHBAUM on 30 Nov 2015 at 15:10
The proper motion measurements combined with the the radial velocities, are important tools for our understanding of the dynamics and evolution of galaxies in a group environment. One of our nearest group is the M81 group at a distance of 3.63 \pm 0.34 Mpc. It is a fascinating interacting galaxy system containing galaxies M81, M82 and NGC 3077. This work present the proper motions of M81 and M82 g ... More
Presented by Mr. Naftali KIMANI on 2 Dec 2015 at 09:55
The ultra-high angular resolution of RadioAstron space-VLBI observations provides an opportunity to study the relativistic jet structure in nearby radio galaxies at a spatial resolution of only a few to a few hundreds of Schwarzschild radii at centimeter wavelengths. Such observations complement the ground-based mm-VLBI experiments in probing the jet acceleration and collimation zone and offer a u ... More
Presented by Dr. Tuomas SAVOLAINEN on 1 Dec 2015 at 16:50
Type: Contributed Session: Session IX - mm-VLBI and the KVN
AGN with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency and polarimetric VLBI observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. In this talk, I will present results from first-epoch data obtained by the Korean VLBI Netw ... More
Presented by Mr. Jae-Young KIM on 2 Dec 2015 at 14:40
We present multi-wavelength studies of the blazar CTA102 and the radio galaxy 3C120 during unprecedented γ-ray flares for both sources. The Fermi Large Area Telescope registered in September-October 2012 an extraordinary bright γ-ray outburst in the quasar CTA102, and between December 2012 and October 2014 a prolonged γ-ray activity in the radio galaxy 3C120. In both studies the analysis of Fer ... More
Presented by Ms. Carolina CASADIO on 2 Dec 2015 at 16:50
Type: Contributed Session: Session I - RadioAstron
The unrivalled angular resolution of Space VLBI being coupled with the natural physical “zooming” properties of the expanding Universe make high-redshift compact radio sources a very valuable targets for observations at extremely long baselines. In this brief review I will revisit the legacy of the high-redshift project conducted with the VSOP about 15 years ago and present a report in progres ... More
Presented by Prof. Leonid GURVITS on 30 Nov 2015 at 13:50
The RadioAstron mission has succeeded in detection of Galactic and extragalactic H2O masers in its ultimate angular resolution finer than 100 microarcseconds. The maser emission in extreme physical conditions will be explored in further image synthesis and astrometry. Here we present the H2O masers in the massive-star forming region W3 IRS5 observed with the RadioAstron and the VERA (Japanese VLBI ... More
Presented by Dr. Hiroshi IMAI on 2 Dec 2015 at 11:25
Type: Contributed Session: Session IX - mm-VLBI and the KVN
In August 2008, Fermi/LAT discovered the distant blazar PKS 1502+106 (z=1.839) showing a rapid and strong gamma-ray outburst followed by bright and variable flux over the next months. This activity at high energies triggered an intensive multi-wavelength campaign indicating that the outburst was accompanied by a significantly delayed counterpart at radio bands. Utilizing ultra-high angular resolu ... More
Presented by Dr. Vassilis KARAMANAVIS on 2 Dec 2015 at 14:00
Owing to their compactness and high brightness, molecular masers are ideal targets for high-angular resolution VLBI. At cm wavelengths, intense maser transitions, in particular the 6.7 GHz CH$_3$OH and the 22.2 GHz H$_2$O lines, are extensively observed in high-mass star forming regions and provide unique diagnostic probes. Multi-epoch VLBI observations can provide the 3D kinematics of the circums ... More
Presented by Dr. Ciriaco GODDI on 2 Dec 2015 at 09:35
The frequency range and sensitivity of the RadioAstron system make it possible to detect a few of the most powerful extragalactic water MegaMasers. Single maser features have been detected in two well-known sources NGC4258 and NGC 3079 at baselines of 1.8 and 2.2 ED. These features represent a small part of the complex spectral signature of these sources. In this paper we present these results and ... More
Presented by Prof. Willem BAAN on 2 Dec 2015 at 11:45