EVN and Global VLBI results and images

We present recent results and images made with the European VLBI Network, often in conjunction with other telescopes - predominantly MERLIN, the VLBA or VSOP. Click on the links below for the full resolution images. In most cases a brief description of the experiment and the significance of the result is also provided. Links to electronic versions of associated publications are listed where possible. We encourage PIs to contact us if they have any EVN results that they would like to highlight on these pages.

If you would like to make use of any of these images please send an email to Zsolt Paragi. We will then seek permission from the author. Use of EVN images in any publication should clearly acknowledge the European VLBI Network.


Location of current and future EVN stations Location of current and future EVN stations

The European VLBI Network (EVN) is an interferometric array of radio telescopes spread throughout Europe and beyond. The figure color-codes:

  • yellow/red - existing operational stations
  • blue - new stations not yet fully participating
  • purple - non-EVN stations that sometimes participate
  • green/brown - non-EVN stations with whom initial EVN-tests have been carried out
Observations are also often conducted in conjuction with the VLBA, GBT, and/or VLA telescopes in the U.S. (not shown). A higher resolution (2048x2048) version of this map is also available.
The underlying map was generated from EarthView, specifically this page to get a form to specify a "satellite-view" of the planet.
World map of current EVN stations The world map at left displays all current (December 2011) EVN stations, plus the correlator at JIVE. This 1800x1067 pixel image was produced using a Blue Marble Next Generation image from NASA Visible Earth. This map is also available in other sizes and with other telescope subsets. Contact Paul Boven (boven@jive.eu) for permission and more information.

A Google map of EVN Facilities is also available.


Serendipitous discovery of the long-sought AGN in Arp 299-A

Within the constellation of Ursa Major, at a distance of 44 Mpc lies the luminous infrared galaxy Arp 299, which is the result of the merging of two galaxies, IC 694 (also known as Arp 299-A) and NGC 3690 (=Arp 299-B1). The large far-infrared luminosity of Arp 299-A, which accounts for about 50% of the total in Arp 299, should result in about 1 SN/yr if standard relations between far-infrared luminosity and core-collapse supernova (CCSN) rates hold.

Arp 299-A was observed with the e-EVN in 2008, and indeed a large number of compact sources were found in its inner 150 pc, most likely young CCSNe and supernova remnants (SNRs) (see below and Perez-Torres et al. 2009, A&A, 507, L17). Further observations were requested, this time using the full EVN at 1.7 and 5.0 GHz, to characterize the nature of all these compact sources and with the final aim of determining the core-collapse supernova rate for this galaxy after a three-year long monitoring.

Fig. 1 shows a "spin-off" result from these observations. The top panel shows the inner 150 pc region of Arp 299-A as imaged with the full EVN at 5.0 GHz, with all the white blobs being the compact sources we wanted to characterize. What caught our interest was the line of objects toward the top right of this image (the A1-A5 region). This was not a chance alignment, but could either be a chain of supernovae and SNRs in a super star cluster approximately 500 years old, or a core and jet of a hidden AGN. The chances that the objects belong to such superstar cluster are less than 3 in a million, and therefore this possibility was ruled out. On the other hand, the morphology, radio luminosity, spectral index and ratio of radio-to-X-ray emission of the A1~VA5 region are consistent with a low-luminosity AGN (LLAGN). The A1~VA5 region was therefore identified with the long-sought AGN in Arp 299-A.

Interestingly, the object labelled A0 is not part of the AGN. Actually, it is a supernova discovered in 2004 by Neff and collaborators. At a mere projected distance of less than 2 pc from the AGN, it is one of the closest to a central supermassive black hole ever detected. It is very likely that this vicinity of massive stars could be the reason why Arp 299-A AGN is so weak ~V nearby massive stars heating their surroundings and dispelling the material that it would normally accrete.

Full details can be found in A&A ( Perez-Torres et al. 2010, A&A, 519, L5), where this Figure is one of the three highlights for the Vol. 519 of the September 2010 issue.

Authors: Miguel A. Perez-Torres, Antonio Alberdi, Cristina Romero-Canizales (IAA-CSIC,Granada, Spain), and Marco Bondi (IRA-INAF, Bologna, Italy)


C-band Origin of the complex radio structure in BALQSO 1045+352 - EVN and MERLIN observations

We present new more sensitive high-resolution radio observations of a compact BAL quasar, 1045+352, made with the EVN+MERLIN at 5 GHz. They allowed us to trace the connection between the arcsecond structure and the radio core of the quasar. The radio morphology of 1045+352 is dominated by a knotty jet showing several bends (click on Figure to see the full version).

The possible scenarios explaining such complex morphology are: galaxy merger, accretion disc instability, precession of the jet and jet-cloud interactions. It is possible that we are whitnessing in this source an ongoing jet precession due to internal instabilities within the jet flow, however, a dense environment detected in the submillimeter band and an outflowing material suggested by the X-ray absorption can strongly interact with the jet. It is difficult to establish the orientation between the jet axis and the observer in 1045+352 because of the complex structure. Nevertheless taking into account the most recent inner radio structure we conclude the radio jet is oriented close to the line of sight which can mean that the opening angle of the accretion disc wind can be large in this source. We also suggest that there is no direct correlation between jet-observer orientation and a possibility of observing BALs.

1045+352 is a CSS object and a HiBAL quasar at a medium redshift. Its linear size (~4 kpc) indcate it is a young object in the early phase of quasar evolution. The radio morphology of 1045+352 is dominated by the strong radio jet resolved into many sub-components and changing the orientation during propagation in the central regions of the host galaxy. As a consequence we observe at least three phases of jet activity indicate different directions of the jet outflow: components A2-A3 as the oldest one, structure A1-B as the younger one, and the jet A as the current activity direction (see Figure).

These results were published in the following two papers:

Kunert-Bajraszewska, M., Siemiginowska, A., Katarzynski, K.,
Janiuk, A., 2009, ApJ, 705, 1356

Kunert-Bajraszewska, M., Janiuk, A., Gawronski, M.,
Siemiginowska, A., 2010, ApJ, 718, 1345


An extremely prolific supernova factory in the buried nucleus of the starburst galaxy IC694

The central kiloparsec of many local uminous infrared galaxies are known to host intense bursts of massive star formation, leading to numerous explosions of core-collapse supernovae. However, the dust-enshrouded regions where those supernovae explode hamper their detection at optical and near-infrared wavelengths.

The nuclear region of the starburst galaxy IC 694 (=Arp 299-A) was investigated at radio wavelengths, aimed at discovering recently exploded core-collapse supernovae, as well as determining their rate of explosion, which carries crucial information about star formation rates, the initial mass function, and the starburst processes in action.

The observations were carried out with the European VLBI Network (EVN) in realtime e-VLBI mode at 5 GHz, providing milliarcsecond resolution to image the innermost nuclear region of IC 694. A rich cluster of 26 compact radio emitting sources were detected in the central 150 pc of the nuclear starburst in IC 694. The high brightness temperatures observed for the compact sources are indicative of a non-thermal origin for the observed radio emission, implying that most, if not all, of those sources are young radio supernovae and supernova remnants. There is evidence of at least three relatively young, slowly evolving, long-lasting radio supernovae (A0, A12, and A15 in the image) that appear to have unusual CCSN properties, suggesting that the conditions in the local circumstellar medium (CSM) play a significant role in determining the radio behaviour of expanding SNe. Their radio luminosities are typical of normal RSNe, which result from the explosion of type IIP/b and type IIL SNe. All of these results provide support for a recent (less than 10-15 Myr) instantaneous starburst in the innermost regions of IC 694, and confirm that the inner regions of Arp 299-A are an extremely prolific supernova factory.

The above results were published as a Letter to Astronomy and Astrophysics (A&A, 507, L17) in November 2009 and are part of a three-year long monitoring of Arp 299-A, using both the full EVN, as well as the e-EVN, aimed at directly determining the core-collapse supernova of the galaxy - model independently - and testing the standard far infra-red/core-collapse supernovae relationships.

Authors: Miguel A. Perez-Torres, Antxon Alberdi, Cristina Romero-Canizales (IAA-CSIC,Granada, Spain), and Antonis Polatidis (JIVE/Astron)


C-band L-band An AGN in the heart of a suspected "dark lens" galaxy

Recently Ryan et al. (2008, ApJ 688, 43) found and optical arc which looks like a gravitationally lensed image of a galaxy. However, the foreground lensing object apparently needed for producing such an arc is not seen in the deep optical and infrared images. The high mass-to-light ratio implied by the non-detection would even allow that the total mass of this galaxy (about 1012.5 solar mass derived from lens modelling) is primarily in the form of dark matter. This could have been the first known example of a "dark lens", or, perhaps less exotically, an unusually obscured galaxy. The only definite information known about the suspected lens is that there is a radio source (J1218+2953) in this position, about 4" away from the optical arc. Its integrated flux density is 33.9 mJy at 1.4 GHz, according to the VLA FIRST survey. The radio spectrum of the source is steep, with a spectral index of -0.7.

The source was detected in short 2-hour e-EVN observations at 1.6 GHz on 23 January 2008, indicating that there was an active galactic nucleus (AGN) in the lensing galaxy. It was resolved into two components separated by about 0.5". Full-track e-EVN observations were quickly proposed at both 1.6 and 5 GHz as well. J1218+2953 was observed in phase-reference mode for 8 hours at 5 GHz on 24 March 2009 (top), and at 1.6 GHz on 21 April 2009 (below). At the lower frequency, the tapered image reveals a rich and complex structure in a nearly symmetrical "inverted S" shape, spanning almost 0.7". Although the redshift of the optically unidentified source is not known, the corresponding projected linear size could be 5-6 kpc. The two brightest components are also seen in the 5-GHz image. There seems also a weak, relatively flat-spectrum feature in between, which might mark the center of this galaxy. The source appeared unresolved with the Westerbork synthesis array, of which the data were recorded during the e-EVN observations. A comparison of the total flux density with the correlated VLBI flux density showed that most of the flux density was recovered with VLBI, indicating that the source is not a lensed image of the background object (otherwise most of the total radio flux density would come from the highly magnified optical arc). Instead, J1218+2953 looks like a young, recently triggered and heavily obscured AGN. It grows in a dense interstellar medium which might cause the observed two-sided bent radio jet structure. This makes the "dark lens" interpretation unlikely.

More details on the observations of this interesting object will be published in Astronomy and Astrophysics. For more details see the online preprint. S. Frey (FOMI SGO), Z. Paragi, B. Campbell (JIVE), A. Moor (Konkoly Obs.)


J0948+0022 Global e-VLBI observations reveal relativistic jet in a Narrow Line Seyfert 1 galaxy

Radio-loud narrow line Seyfert 1 (NLS1) are Active Galactic Nuclei that have received considerable attention lately, since they pose a challenge to current unified schemes. Only a small percentage (about 7%) of NLS1 are radio-loud and in these cases the flat radio spectra and VLBI variability suggest that they could host relativistic jets. The detection by the Large Area Telescope (LAT) on board Fermi of gamma-rays from a handful of NLS1 has recently set the definitive confirmation of the presence of a relativistic jet in these sources.

A multi-wavelength campaign has been organized to investigate the properties of the prototypical NLS1 PMN J0948+0022 with simultaneous data for the first time. For this campaign, a series of global e-VLBI observations were organized between April and July 2009. The observing frequency was 22 GHz and the participating telescopes were Cambridge, Effelsberg, Jodrell Bank, Medicina, Metsahovi, Onsala, Shanghai, and Yebes from the EVN; Hobart, Mopra, Parkes, and the ATCA from the LBA; and Kashima in Japan. Radio telescopes in Darnhall and Torun participated in an EVN pilot test at 1.6 GHz prior to the 22 GHz campaign.

The observations were a success, with real time fringes detected to all telescopes in at least one epoch, which is a great achievement for the eVLBI technique. Indeed, this was the first scientific experiment using a global array connected in real time; moreover, it was carried at a comparatively short wavelength. The source was clearly detected on baselines longer than 900 million wavelengths (12,000 km), resulting in a resolution of about 0.2 x 0.5 milliarcsecond. Polarized emission, offset form the core and in the direction of jet emisssion observed at lower frequencies, was also detected at a significant level (shown in colours).

The results of the multi-wavelength campaign - which involved several instruments and satellites from radio to the gamma-rays- are already published in a paper by Abdo et al. (2009, ApJ 707, 727), while the details of the e-VLBI data analysis will be presented in a future work (Giroletti et al., in preparation).


3C395 e-VLBI observation of 3C395

As part of an e-VLBI test on 5 February 2008, we observed 3C395 with six stations (Medicina, Westerbork, Onsala, Torun, Cambridge and Jodrell Bank) at approximately 1 Gbps to produce the image at left. (Only formatter data was sent from Onsala for this test.)


Sources from the Deep Extragalactic VLBI-Optical Survey (DEVOS) Sources from the Deep Extragalactic VLBI-Optical Survey (DEVOS)

The Deep Extragalactic VLBI-Optical Survey (DEVOS) aims at constructing a sample of compact radio sources up to two orders of magnitude fainter than those usually studied with VLBI. Recent 5-GHz phase-referencing observations with the EVN (EF016, 2 March 2007) targeted 26 radio sources around two compact calibrators. Optical identifications were ensured by selecting objects from the Sloan Digital Sky Survey (SDSS). An efficient way to identify potential VLBI targets with mas-scale compact radio structures at >1 mJy flux density level was found. Nearly 90% of the sources that are unresolved both in SDSS (i.e. optical quasars) and in the VLA Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey (<5", >20 mJy) have been successfully detected with the EVN. Images of four such quasars in a wide range of redshifts are shown here as an example. Peak brightnesses (from the top left corner) are 83.5, 13.5, 27.5 and 8.6 mJy/beam. Typical 3-sigma lowest image contours were 0.3 mJy/beam in the survey.

Frey, S., Gurvits, L.I., Paragi, Z., Mosoni, L., Garrett, M.A., Garrington, S.T. (2008), A&A 477, 781
E-journal

SN 2007gr e-VLBI observation of SN 2007gr

The observation was conducted on 6-7 September 2007 for 12 hours at 4.97 GHz with the the European VLBI Network (EVN) at an aggregate bitrate of 256 Mbps. The observation identified an unresolved source. It is therefore considered an e-VLBI detection of a supernova, and further observations are planned. This observation and the resulting publication are only possible because of the rapid response time of e-VLBI.

Paragi, Z.; Kouveliotou, C.; Garrett, M.A.; Ramirez-Ruiz E.; Langevelde, H.J. van; Szomoru, A.; Argo, M. "e-VLBI detection of SN2007gr. " The Astronomer's Telegram. #1215. (12 September 2007).

e-VLBI observations of Cygnus X-3 e-VLBI observations of Cygnus X-3

Cygnus X-3 is an X-ray binary system containing an unknown compact object (black hole or neutron star) accreting matter from a Wolf-Rayet star. In some particular states, matter is ejected from a region close to the compact object in the form of two opposite, relativistic jets in a plane nearly perpendicular to the accretion disk. Evidence shows that when present, the jets are oriented very close to the line of sight, so we are actually looking more or less into the approaching jet. Taking advantage of state of the art e-VLBI techniques, we have observed Cygnus X-3 at 5 GHz on 2006 April 20, when the system was in a quasi-quiescent state (relatively low flux at radio wavelengths), and 2006 May 18, a few days after a major flare. On the first epoch we detected faint emission probably associated with a fading jet. The second epoch, in contrast, reveals a bright, curved, relativistic jet more than 40 mas in extent. These results were obtained within the framework of the first open call for e-EVN observations (see also Rushton et al., 2007, MNRAS, 374, L47).

Tudose, V., Fender, R.P., Garrett, M.A., Miller-Jones, J.C.A., Paragi, Z., Spencer, R.E., Pooley, G.G., van der Klis, M., and Szomoru, A. 2005, MNRAS, 375, L11
E-journal

Discovery of a methanol maser ring
Discovery of a methanol maser ring
Discovery of a methanol maser ring

The methanol maser transition at 5 cm was observed on 2004 November 11 towards the Galactic source G23.657-0.127, using eight antennas of the EVN (Cambridge, Darnhalll, Effelsberg, Medicina, Noto, Onsala, Torun and Westerbork). The unique circular ring-like structure has a mean radius of 127 milliarcseconds. Assuming the near kinematic distance of 5.1 kpc, the radius of the maser ring is 650 AU (about 16 times larger than the Solar System). In principle there are two three-dimensional structures that project onto the sky as a ring structure like the one observed. These are a circumstellar disk seen face-on or a spherical bubble which may be the shock front originating from the central star and propagating into the circumstellar gas. Proper motions studies of maser clouds are undertaken to reveal the origin of the structure, by measuring expansion or rotation.

Bartkiewicz A., Szymczak M. & van Langevelde H.J., 2005, A&A, 442, L61
E-Journal

Collimated Jet in Seyfert 1 galaxy NGC4051 Collimated Jet in Seyfert 1 galaxy NGC4051

The narrow line Seyfert 1 galaxy NGC4051 is one of the nearest, brightest, and most highly variable of the X-ray active galaxies (McHardy et al. 2004). Like many Seyfert galaxies it has weak radio emission (Christopoulou et al. 1997). The nature of that emission is generally unknown although, in NGC4051, it has been suggested that the inner part of the accretion flow may become advective during periods of low X-ray flux (Peterson et al 2000), which should lead to enhanced radio emission. Thus radio emission would be anti-correlated with the X-ray emission.

In order to determine whether the above hypothesis was correct, we carried out joint radio (VLA) and X-ray (Rossi X-Ray Timing Explorer, RXTE) monitoring of NGC4051 for a year, at two-weekly intervals. We found that the X-ray and radio emission was positively correlated (McHardy et al, in preparation), suggesting jet-like emission rather than any mechanism related to an advective flow.

The VLA maps from various configurations, which are some of the deepest ever made of a Seyfert galaxy, reveal structure similar to that of a normal extragalactic FRI radio source, except that the size and luminosity are much lower than average. Interestingly, the A-configuration map, and a MERLIN map (Christopoulou et al. 1997) show three components of sub-arcsecond scale in the nucleus. The central component has a flat spectrum and the outer component have normal steep spectra.

To determine whether the nuclear components were simply diffuse outflows, unresolved by MERLIN and the VLA, we carried out 1.6 GHz EVN and EVN+VLBA phase-referencing observations in May 2003 and June 2004, respectively. The resulting maps clearly show that each component is highly compact and almost all of the flux seen in the VLA A-configuration and MERLIN maps is contained within those compact components. The only explanation for this compact structure is that we are observing a highly collimated beam, and are detecting the central core and also the outer hot spots. The separation of the hot spots from the core (about 25pc) is consistent with the beam impacting onto a surrounding torus. It has previously been thought that the emission from Seyfert galaxies is broadly isotropic, but here we have found a highly collimated jet, more typical of classical extragalactic radio sources and blazars. Perhaps jets exist, at some level, in all active galaxies.

The outer components C and D are somewhat asymmetric with respect to the core: (A-D) = 439 mas and (A-C) = 462 mas. The core region can be fit with two Gaussians (A,B), with a relative separation of 6 mas.

Christopoulou, P.E. et al. 1997, MNRAS, 284, 385
McHardy, I.M. et al. 2004, MNRAS, 348, 783
Peterson, B., McHardy, I.M. et al. 2000, ApJ, 542, 161

Tentative detection of Supernova with real-time EVN Tentative detection of Supernova with real-time EVN+MERLIN

The e-VLBI technique has made it possible to transfer the data from a number of European VLBI Network (EVN) telescopes to the central data processor at JIVE through optical fibres, and correlate them in real time. This image shows SN2001em, a Type Ib/c supernova observed with e-EVN+MERLIN. The source is marginally detected in the radio observations. The data show that SN2001em either started fading in the last couple of months, or its radio spectrum is inverted at low frequencies,indicating free-free or synchrotron self-absorption. This is quite unusual, but not unprecedented in radio SNe.

Paragi et al. (2005) Mem. S.A.It. 76, 570

The first real-time EVN image The first real-time EVN image

Wednesday 28 April 2004 saw the production of the first ever real-time EVN image. Data from three telescopes of the European VLBI Network (EVN) were sent directly into the EVN MkIV Data Processor at JIVE and correlated, without the data at any time having been stored on disk. The experiment used telescopes located in Onsala (Sweden), Jodrell Bank (UK) and a single antenna of the Westerbork Synthesis Radio Telescope (the Netherlands). The source observed is a gravitational lens system, JVAS B0218+357. A lens system arises when the light from a distant object is deflected by an intervening massive galaxy. This causes the distant object to be distorted and can result in it being split into multiple images. In the case of 0218+357, we see two images of a bright radio quasar, separated by 334mas.

Image courtesy of the EVN and JIVE

The obscuring circumnuclear torus in Mrk231 The obscuring circumnuclear torus in Mrk231

Observations with the EVN of powerful Hydroxyl (OH) emissions from the active galaxy Mrk231 (the most luminous galaxy in the local universe) reveal an emission structure consistent with a rotating, dusty, molecular torus. The images shown here (from left to right) are of the OH line velocity field, the velocity dispersion structure and finally a model of the nuclear torus. These observations strongly support the unification schemes that have been proposed for active galaxies.

Klöckner H-R., Baan W.A. & Garrett M.A., 2003, Nature, 421, 821 E-journal

Persistent relativistic radio jets in the microquasar LS 5039 Persistent relativistic radio jets in the microquasar LS 5039

LS 5039/RX J1826.2-1450 is a high-mass X-ray binary in our Galaxy, previous VLBI images of which revealed the presence of relativistic radio jets, indicating that LS 5039 was a microquasar. The EVN (right) and MERLIN (left) 5-GHz images shown here detect the jets, confirming their long-lived nature, and demonstrate that they are slightly asymmetric and extend to a distance of ~1000AU from the core. Therefore, this source appears to be a rather good natural laboratory to explore the accretion/ejection processes taking place near compact objects. Finally, LS 5039 may be associated with the high-energy gamma-ray source 3EG J1824-1514. There are still 170 unidentified EGRET sources, and some of them could be associated with microquasars.

Paredes J. M., Ribó M., Ros E., Martí J., Massi M., 2002, A&A, 394, 983 E-journal

Edge of the universe as seen by the EVN Edge of the universe as seen by the EVN

The object SDSS 0836+0054 at z=5.82 is the highest redshift radio-detected quasar known to date and was discovered during the Sloan Digital Sky Survey. The detected radiation was emitted at a time when the Universe was ~7% of its present age placing SDSS 0836+0054 close to the edge of the Universe. The target source was clearly detected by the EVN with a dynamic range of ~10. The noise of the target image is about 34 microJy/beam and the peak flux density of the image 770 microJy/beam. This EVN image is one of the most sensitive VLBI images ever obtained and allows us to rule out strong gravitational lensing of this object predicted in recent theoretical works.

Frey S., Mosoni L., Paragi Z., Gurvits L.I., 2003, MNRAS, 343, L20 E-journal

Global VLBI observations of a distorted radio shell in the young supernova SN1986J A distorted radio shell in the young supernova SN1986J

SN 1986J in the galaxy NGC 891 is one of the most radio luminous supernovae ever discovered. Left: VLA image of NGC 891 at 5 GHz. The brightest spot in the galaxy is SN1986J. Right: Global VLBI image of SN1986J at the same epoch and observing frequency. This high-resolution image shows a distorted shell of radio emission, indicative of a strong deformation of the shock front. There are several bright knots that delineate a shell-like structure, and an absolute minimum of emission, which could be tentatively identified with the centre of the supernova explosion. If this is the case, SN1986J has then suffered an asymmetric expansion which is likely due to collision of the ejecta with an anisotropic, clumpy (or filamentary) medium.

Perez-Torres M.A., et al., 2002, MNRAS, 335, 23 E-journal

EVN observations of young, radio-loud AGN EVN observations of young, radio-loud AGN

Shown here are EVN and EVN+VLBA images of several sources observed from a complete sample of young radio-loud AGN at low redshift (z<0.2). This new sample is used for statistical studies of the early evolution of young radio sources, free of cosmological evolution effects. The morphologies of these sources are consistent with them being compact doubles, as expected for these objects. Future multi-epoch VLBI observations will enable the determination of their dynamical ages. The dependence of age on radio luminosity and linear size, in combination with their overall luminosity function and source size distribution will put strong constraints on possible evolution scenarios.

Snellen I., et al., in preparation

Global VLBI observations of JVAS B0218+357 Global VLBI observations of JVAS B0218+357

JVAS B0218+357 is one of the most intriguing of gravitational lens systems and an excellent tool for the determination of the Hubble parameter. The figure here shows the two images (A - top, B - bottom) at 8.4 GHz with a resolution of ~1-mas. Both are dominated by two bright core components, but these observations show, for the first time, the extended emission of the radio jet. Image A is tangentially stretched compared to B and various instances of parity reversal can be seen - a textbook case of gravitational lensing.

Biggs A.D., et al., 2003, MNRAS, 338, 539 E-journal

Global VLBI movie of the binary star system Scorpius X-1 Global VLBI movie of the binary star system Scorpius X-1

In the movie, the EVN images come from the time range 18:00 to 01:00 on two days. The ejection of the component occurs mostly during the EVN session, and the second flare in the core is also mostly EVN images.

Fomalont E. B., Geldzahler B. J., Bradshaw C. F., 2001, ApJ, 553, L27 E-journal


EVN observations of the Hubble Deep Field
EVN observations of the Hubble Deep Field
EVN observations of the Hubble Deep Field

Top: The faintest radio sources ever detected using high resolution Very Long Baseline Interferometric techniques - EVN images of radio sources detected in the Hubble Deep Field. These images are overlayed upon a radio contour map of the region produced by the Westerbork Radio Telescope (yellow contours), which is itself superimposed upon a deep optical image of the HDF region made by the Canada-France-Hawaii telescope (courtesy Amy Barger, et al.). Bottom: an alernative image showing the optical image in colour with the EVN images again shown as insets. Also see PR.

Garrett M.A., et al., 2001, A&A, L5 E-journal


EVN+VSOP image of 0014+813
EVN+VSOP image of 0014+813

At a redshift of 3.366, 0014+813 is one of the most luminous quasars in the Universe, lying at a distance of 13.6 billion light years. The figure shows 1.6 GHz images of the quasar 0014+813, obtained with the EVN (left panel) and VSOP (right panel), the first dedicated Space VLBI mission. The VSOP observation was made with the Japanese Space Radio Telescope HALCA, six telescopes of the European VLBI Network and the NRAO Green Bank 43 m telescope. Space-ground baselines (right panel) make it possible to zoom in the source radio structure with the magnification factor of ~3. The synthesized beam of the Space VLBI image is 2x1 mas (FWHM).

Gurvits L.I., et al., in preparation


EVN+VLBA image of B2 1144+35
EVN+VLBA image of B2 1144+35
EVN+VLBA image of B2 1144+35

Global VLBI image at 8.4 GHz of 1144+35. The HPBW is 1.45 x 0.66 mas in PA -13. The nuclear source is the strong component located at about -10 (RA) and +10 (Dec) mas from the image center. The NW component is a short counter-jet, while the extended and complex structure SE to the core is the main jet component. Multi epoch images show that the main jet is moving with respect to the core with an apparent velocity of 2.7c.

Giovannini G., Taylor G. B., Arbizzani E., Bondi M., Cotton W. D., Feretti L., Lara L., Venturi T., 1999, ApJ, 522, 101 E-journal


Compact 1667 MHz OH masers around IK Tau
Stokes V OH 1667 MHz maser emission from VX Sgr
EVN and EVN+VLBA (Global VLBI) Observations of 2 OH masers

Top: Compact 1667 MHz OH masers around IK Tau detected by the EVN with sufficient resolution to measure proper motions, superimposed on a MERLIN map.

Bottom: EVN/Global VLBI map of Stokes V OH 1667 MHz maser emission from VX Sgr, showing the proposed direction of the magnetic field axis.

Richards A.M.S., et al., 2000, Proc. of EVN Symposium 2000, p.185 PDF (ADS)


EVN+VLBA (Global VLBI) Observations of 0820+225 EVN+VLBA (Global VLBI) Observations of 0820+225

Top: Global 6cm VLBI image of 0820+225. Bottom: Lower resolution 6 cm VLBA image of 0820+225 with distributions of the spectral index (left) and rotation measure (right) superposed. All images from Gabuzda, Pushkarev and Garnich.

Gabuzda D. C., Pushkarev A. B., Garnich N. N., MNRAS, 2001, 327, 1 E-journal


EVN+VLBA+GreenBank HI profiles toward 1946+708 EVN+VLBA+GreenBank HI profiles toward 1946+708

The distribution of the neutral hydrogen in the central ~50 parsecs of compact radio galaxies can be traced by observing the 21 cm line in absorption. The profiles shown here toward the Compact Symmetric Object 1946+708 indicate a circumnuclear torus comprised of predominantly neutral gas. Evidence of this torus is also detected in the ionized gas by imaging free-free absorption.

Peck A. & Taylor G., 2001, ApJ, 554, L147 E-journal


The starburst galaxy M82 EVN-only and Global VLBI Observations of M82

The LH picture shows the MERLIN+VLA 20cm image of M82 with an inset showing one of the supernova remnants imaged by EVN at two epochs - 1986 and 1997. By comparing the shell sizes an average expansion velocity of 9500km/s can be estimated - consistent with an age of ~30-40 years (Pedlar et al. 1999). The RH picture shows the same supernova imaged with global VLBI at 20cm with 3mas (0.05 pc) resolution.

McDonald A.R., et al., 2001, MNRAS, 322, 100 E-journal


EVN Observations of NGC4261 EVN Observations of NGC4261

Hubble telescope image of the accretion disk in NGC4261, and a VLBI map of its nucleus. The spectrum of atomic Hydrogen gas at the location where the inner part of the disk covers the radio source. This result is the first scientific outcome of the EVN MkIV data processor at JIVE.

van Langevelde H.B., Pihlström Y.M., Conway J.E., Jaffe W., Schillizi R.T., A&A, 354, L45 E-journal


Gravitational Lens MG J0414+0534 Global VLBI 8.4-GHz Observations of the Gravitational Lens MG J0414+0534

The lens system MG J0414+0534 comprises four images of a z=2.64 QSO. These images illustrate how the gravitational potential of the lensing galaxy distorts the structure of the background object - rotating, translating and "flipping". Image A1 in this system is particularly distorted.

Ros E., et al., 2000, A&A, 362, 845 E-journal


Global VLBI Observations of SN1993j Global VLBI Observations of SN1993J

VLBI observations of SN1993J at wavelengths of 3.6, 6, 13 and 18cm since 1993 have shown that the expansion of the shell-like radio structure, discovered in 1995, is self-similar and is decelerating, yielding support to a binary scenario for the progenitor. An avi movie (gzipped) of the expansion can be found here.

Marcaide J., et al., 1997, ApJ, 486, L31 E-journal


Global VLBI Observations of SN1993J
Global 8.4-GHz VLBI Observations of SN1993J
Global VLBI Observations of SN1993J

These observations of supernova SN1993J used the technique of phase referencing that has enabled extremely accurate positions for the radio emission to be determined. The phase-reference source was the nucleus of M81, the host galaxy of the supernova.

e.g. Bietenholz M. F., Bartel N., Rupen M. P., 2001, ApJ, 557, 770 E-journal

EVN 6.7GHz observations of the disk-like structure seen edge-on in NGC7538 EVN 6.7GHz observations of the disk-like structure seen edge-on in NGC7538

In the figure the color scale represents the velocity whilst the spot size scales with the flux density.

Minier V., Booth R. S., Conway J. E., 1998, A&A, 336, L5E-journal


EVN+Halca Global VLBI Observations of Mrk421 EVN+Halca Global VLBI Observations of Mrk421

Mkn 421 was observed at a number of epochs and frequencies with the EVN, VLBA, and VSOP. The images show subluminal, mildly relativistic, motion on the parsec-scale. Since highly relativistic motion in the core is required to explain the TeV gamma-ray variability, this suggests deceleration of the jet between the TeV emitting region and parsec-scales.

Piner B. G., Unwin S. C., Wehrle A. E., Edwards P. G., Fey A. L., Kingham K. A., 2001, AJ, 122, 2954 E-journal


EVN, MERLIN and Global VLBI Images of SS433 EVN, MERLIN and Global VLBI Images of SS433

Global VLBI and MERLIN observations of the precessing beams of the Galactic radio-jet X-ray binary ("microquasar") system SS433 at 1.6 GHz are shown in the top figure. Focusing on the central parts of the source (bottom) reveals the Equatorial Emission Region (discovered by Paragi et al., 1999, A&A 348, 910), quasi-perpendicular to the normal jets. This region changes with the precession cycle. It is most probably related to an equatorial outflow from the binary system.

e.g. Paragi Z., Fejes I., Vermeulen R. C., Schilizzi R. T., Spencer R. E., Stirling A. M., 2001, ApSSS, 276, 131


EVN, MERLIN and VLA 18cm Observations of 3C264 EVN, MERLIN and VLA 18-cm Observations of 3C264

3C264 is an FR-I source that contains a jet that is clearly visible in both the radio and the optical. Seen with the VLA, MERLIN and the EVN, the different resolutions reveal radio emission on different scales, from the large extended lobes seen with the short baselines of the VLA to the collimated jets that are seen at the highest resolution with the EVN.

Lara L., Giovannini G., Cotton W. D., Feretti L., Venturi T., 2002, Proc. of EVN Symposium 2000, p.23 PDF (ADS)


EVN+MERLIN 6cm and Comparison HST Observations of 3C264 EVN+MERLIN 6-cm and Comparison HST Observations of 3C264

These observations reveal a change in the jet morphology that is coincident with an optical "ring" that has been imaged with the Hubble Space Telescope (HST).

e.g. Baum S. A., et al., 1998, ApJ, 483, 178 E-journal


EVN Global VLBI observations of the CSO 0710+439 EVN Global VLBI observations of CSOs
CSO 0710+439

Owsianik I., Conway J.E., 1998, A&A, 337, 69 E-journal
EVN Global VLBI observations of the CSO 0108+388 CSO 0108+388

Owsianik I., Conway J.E., Polatidis A.G., 1998, A&A, 336, L37 E-journal
EVN Global VLBI observations of the CSO 2352+495 CSO 2352+495

Owsianik I., Conway J.E., Polatidis A.G., 2002, A&A, submitted


EVN+MERLIN VLBI 18cm Observations of Mrk 3
EVN+MERLIN 18cm + HST (OIII)
EVN+MERLIN+HST Observations of Mrk 3

The upper panel shows an EVN+MERLIN 18cm map of the Seyfert 2 Galaxy Markarian 3, showing two highly collimated radio jets and an isolated core component (situated ~0.3 arcsec east of the image centre). The western jet terminates in a bright hotspot containing complex substructure. The spatial scale of the image is 250 pc/arcsec. The lower panel shows the 18-cm radio map (contours) superimposed on the [OIII] emission line structure imaged with HST by Capetti et al. (1995, ApJ, 454, L85).

Kukula M.J., Ghosh T., Pedlar A., Schilizzi R.T., 1999, ApJ, 518, 117 E-journal


5 GHz Global VLBI image of the FRII radio galaxy 3C452 5-GHz Global VLBI image of the FRII radio galaxy 3C452

3C452 was observed with the EVN as part of an effort to observe a large sample of radio galaxies at milli-arcsecond resolution. This source has an FRII morphology on the largest scales and displays very symmetric structure in this high-resolution image.

Giovannini G., Cotton W. D., Feretti L., Lara L., Venturi T., 2001, ApJ, 552, 508 E-journal


8 GHz Global VLBI image of the CSO 1943+546 8 GHz Global VLBI image of the CSO 1943+546

1943+546 is a compact symmetric object (CSO), a class of radio sources that are believed to be relatively young. The age of this source has been estimated at ~1000 years from the detection of increasing separation between the two "hotspots" (brightest points in the image).

Polatidis A., Wilkinson P. N., Xu W., Readhead A. C. S., Pearson T. J., Taylor G. B., Vermeulen R. C., 1999, NewAR, 43, 657 E-journal


Global VLBI 43 GHz images of the jet in M87
Multi-epoch Global VSOP 5 GHz images of the jet in M87
Multi-frequency VLBI images of the jet in M87

M87 (3C274) is a relatively nearby AGN containing a well-studied radio jet. These images show the core and jet when imaged using Global VLBI at 43 GHz (top) and at multiple epochs with a Global VLBI+VSOP (bottom) array at 5 GHz. One interesting aspect of this system is the very wide opening angle of the jet seen at 43 GHz, in stark contrast to the behaviour further along the jet which shows that the emitting plasma is well collimated. From this it is possible to estimate the distance along the jet that the collimation process begins (approximately 100 Schwarzschild radii in this case).

Junor W., Biretta J., Livio M., 1999, Nature, 401, 891 E-journal


EVN+Halca Global VLBI Observations of 2021+614 EVN+Halca Global VLBI Observations of 2021+614

The increase in the separation of the two most prominent components of the GHz-Peaked Spectrum (GPS) radio galaxy 2021+614 has been determined by comparison with previous observations. The projected speed with which these two components recede from each other is 0.12/h c which, given a projected separation of 16.1/h pc, implies a kinematic age of 440 years. This result provides additional support for the contention that compact symmetric radio objects are young and the precursors of the extended radio sources.

Tschager W., Schilizzi R. T., Röttgering H. J. A., Snellen I. A. G., Miley G. K., 2000, A&A, 360, 887 E-journal


Wide-Field EVN Observations of 0957+561 Wide-Field EVN Observations of 0957+561

EVN 18cm observations of the gravitational lens 0957+561. This wide-field image is able to detect for the first time compact features in the extended arcsecond scale jet structures. These data were used to refine wide-field VLBI imaging techniques that were later applied to the HDF (Garrett et al.) and M82 (Pedlar et al.).

Garrett M.A., Porcas R.W., Pedlar A., Muxlow, T.W.B., Garrington S.T., NewAR, 43, 519 Astro-ph


EVN-MERLIN VLBI Observations of 3C236 EVN-MERLIN VLBI Observations of 3C236

Shown here is a 1.6-GHz image of the giant radio galaxy 3C236. With a linear extent of ~4 Mpc, this is the largest known radio source in the universe although this image only shows the inner part (~2kpc) of the source. Its size, as well as the presence of both large-scale (FRI/II) and small-scale (CSS) structures, make it an important object for radio source evolution studies.

Schilizzi R., et al., 2001, A&A, 368, 398 E-journal


Global VLBI 5-GHz image of 3C380 Global VLBI 5-GHz image of 3C380

3C380, a quasar, is one of the most powerful radio sources known and is a member of the Compact Steep Spectrum (CSS) class. On parsec scales the source consists of a one-sided jet which is shown here.

Polatidis A., Wilkinson P. N., in preparation


EVN+MERLIN VLBI 18cm Observations
of the LIRG IIIZw35 EVN+MERLIN VLBI Observations of the LIRG IIZw35

EVN+MERLIN 18cm observations of the luminous infrared galaxy IIIZw35 show the OH megamaser emission to have a ring-like distribution. Such a ring can account for both the compact as well as the diffuse masers observed. The same observations also show compact continuum sources that are consistent with being either radio supernovae or supernova remnants.

Pihlström Y.M., Conway J.E., Booth R.S., Diamond, P.J. & Polatidis A.G., 2001, A&A, 377, 413 E-journal

EVN 6cm observations of lens 2016+112 EVN 6cm observations of lens 2016+112

EVN 6-cm observations of the gravitational lens 2016+112 resolve all three images, A, B and C. In the region of image C the magnification may be a factor of 100 or more thus providing super-resolved maps of the lensed radio source.

Koopmans L.V.E., Garrett M.A., Blandford R.D., Lawrence C.R., Patnaik R.A., Porcas R.W., 2002, MNRAS, 334, 39 E-journal

VLBI observations of Cygnus A with sub-milliarcsecond resolution VLBI observations of Cygnus A with sub-milliarcsecond resolution

The upper image was made with the VLA at 5 GHz and shows two faint jets feeding two extended radio lobes. The remaining VLBI images show the structure surrounding the nucleus. The bottom image shows the inner 3 milli-arcseconds with an angular resolution of 0.15 milli-arcseconds (or 130 light days!). Comparison of the brightness ratio between western and eastern jets at the different wavelengths yields strong evidence for a gaseous torus of absorbing material surrounding the core, which partially blocks the radiation from the counter-jet, but not from the jet.

Krichbaum T., et al., 1998, A&A, 329, 873 E-journal

Last modified: January 12, 2016
EVN webmaster (jive{at}jive.eu)