VSOP Image Gallery

Click on the images shown for the larger versions or, in some cases, links to the investigators' WWW page.

When you are using these images, please follow the ISAS data policy.

Also check out the "Pearson-Readhead survey from Space" VSOP program web page.

VSOP FIRST IMAGES `GENERIC' PRESS RELEASE



  The X-ray Jet Source 0637-752   Early Chandra X-ray Observatory observations of PKS 0637-752 resulted in the surprising detection of an X-ray jet in the object. The image at left shows a VSOP observation of the inner jet region. Click on the image to see the milli-arcsecond-scale VSOP image in comparison with the arcsecond resolution Chandra (pixels) and ATCA (lower contours) images.

This work is described in J. Lovell et al. Astrophysical Phenomena Revealed by Space VLBI, eds. H. Hirabayashi, P.G. Edwards and D.W. Murphy (ISAS) p. 215, which is available from here.  

Image courtesy:  
J. Lovell (ATNF),  


The superluminal quasar 3C345 

The bright quasar 3C345 has been well-studied using the VLBI technique, with previous ground-based observations revealing that jet components travel in curved trajectories away from the core and at apparently superluminal speeds. Observations of this famous quasar at the highest 18cm and 6cm wavelength resolution provided by VSOP were one of the missions key science projects. 3C345 was observed eight times in the first three years of the mission, half the observations being at 18cm (1.6 GHz) and the other half at 6cm (5 GHz). An image of the core and inner jet region is shown in the figure at left. Clicking on the image leads to a comparison of an image made with only the ground radio telescopes (the VLBA, VLA, and Effelsberg), and an image made with the inclusion of the HALCA data, illustrating the gain in resolution achieved with the long baselines to the satellite.

This work is described in J. Klare, J.A. Zensus, E.Ros and A.P. Lobanov (MPIfR), in Astrophysical Phenomena Revealed by Space VLBI, eds. H. Hirabayashi, P.G. Edwards and D.W. Murphy (ISAS) p. 21, which is available from here.

Image courtesy:  
J. Klare (MPIfR)   

 

  The high brightness temperature BL Lac object 0235+164   In 1999, the extremely compact and variable source AO 0235+164 was identified as the highest brightness temperature active galactic nucleus observed with VSOP (at least 6 times 10^13 K, Frey et al. 2000, PASJ 52, 975). We monitored the sub-mas structure of this BL Lac object at a few more epochs in 2001 and 2002. The VSOP image shown (inset, with almost 3 orders of magnitude higher resolution than the VLA image) was made in February 2001. The inner source structure is remarkably simple, although on the long baselines to HALCA, the core seems resolved. It implies about ten times lower brightness temperature than measured 2 years earlier. The source has apparently expanded, and also faded, according to total flux density measurements. The degree of linear polarization in the core was about 1%, at the detection threshold. S. Frey (FÖMI SGO), L.I. Gurvits (JIVE), D.C. Gabuzda (Univ. College Cork), C.J. Salter, D.R. Altschuler, P. Perillat (Arecibo), M.F. Aller, H.D. Aller (U. Michigan), H. Hirabayashi (ISAS), M.M. Davis (SETI Inst.) in Proceedings of the 6th European VLBI Network Symposium, eds. E. Ros , R.W. Porcas, A.P. Lobanov, and J.A. Zensus, (MPIfR, Bonn, Germany) p. 91.  

Image courtesy:  
S. Frey (FÖMI SGO),  


The bright quasar 1546+027 

The relatively nearby (z=0.412) quasar 1546+027 was observed with HALCA and the Effelsberg, Noto, Torun and Hartebeesthoek ground radio telescopes at 5 GHz in August 2000. The source was selected as one of the brightest and most compact objects in the 5-GHz VLBA Prelaunch Survey (VLBApls). Its sub-milliarcsecond (sub-mas) scale radio structure is resolved with space VLBI. The image shows the prominent inner jet structure directed to the South. Radio flux density monitoring data taken over the last couple of years indicate that there was a dramatic outburst in 1996. If the jet component we see now separated by 0.8 mas from the core is associated with that outburst, the source could be a candidate for detecting superluminal motion with an apparent speed of about 3c. There is a misalignment of about 40 degrees between the inner and outer jets: the mas-scale, as well as the arcsecond-scale jet points to the South, while on 10 arcsecond scale a jet component is seen SE from the core.

This work is described in L. Mosoni, S. Frey, Z. Paragi, I. Fejes (FÖMI SGO), P.G. Edwards (ISAS), E.B. Fomalont (NRAO), L.I. Gurvits (JIVE), W.K. Scott (U. Calgary), in Proceedings of the 6th European VLBI Network Symposium, eds. E. Ros , R.W. Porcas, A.P. Lobanov, and J.A. Zensus, (MPIfR, Bonn, Germany) p. 97.

Image courtesy:  
S. Frey (FÖMI SGO)   

 

VSOP images of 1928+738 at 6 cm

Multi-epoch imaging of the quasar 1928+738  

The relatively low-redshift quasar 1928+738 is located in a part of the sky that is always visible to HALCA, making the quasar well-suited to a detailed monitoring program of VSOP observations. Seven 5 GHz images are shown above, the first made in August 1997, the second in December 1997, and the last in September 2001. The horizontal spacing between images is proportional to the time between observations.  

Image courtesy : D.W. Murphy, JPL  


  The bright radio galaxy PKS 0521-365   At right is a 4.8GHz VSOP image of the core of the galaxy PKS 0521-365. The 1 mas (milli-arc-second) bar corresponds to a linear distance of about 1 parsec (3.26 light years) at the distance of the galaxy. VSOP observations together with ground-VLBI observations have been used to that show that any apparent motion of components in the jet of PKS 0521-365 must be less than 1.2 times the speed of light. This, together with the core brightness temperature and jet to counter-jet ratio, suggest PKS 0521-365 is not highly beamed, and constrains previous modeling of the source. Evidence for evolution internal to a jet component is seen, similar to that seen on the sub-parsec-scale in Centaurus A and M87. This work is described in "The parsec-scale structure and evolution of PKS0521-265" by Tingay & Edwards, which appears in the Astronomical Journal, vol. 124, p. 652 (2002).  

Image courtesy:  
S.J. Tingay (ATNF)  
P.G. Edwards (ISAS)  


The distant quasar 1351-018 

The image at right results from a 5-GHz VSOP observation of the extremely distant quasar 1351-018 (z=3.707). Click on the image to see a comparison of two VSOP images, separated by 2.78 years (at left). The change in the position of the innermost jet component implies a proper motion of 0.18+/-0.07 mas/yr, corresponding to an apparent superluminal speed. The high angular resolution of VSOP at this frequency made possible to tentatively detect superluminal motion in a short period of time, which is unique among such high-redshift quasars. The ground-only image at the second epoch (on the right-hand side of the image obtained by clicking on the image on this page), in agreement with earlier VLBI data, indicates a large (130 degrees) misalignment between the 10-milli-arcsecond and sub-milli-arcsecond scale jet direction. This work is described in Frey, S., Gurvits, L.I., Lobanov, A.P., Schilizzi, R.T., Kawaguchi, N., and Gabanyi, K. 2002, in Proceedings of the 6th European VLBI Network Symposium, eds. E. Ros , R.W. Porcas, A.P. Lobanov, and J.A. Zensus, (MPIfR, Bonn, Germany) pp. 89-90.

Image courtesy:  
S. Frey (FÖMI SGO)   

 

  The extremely misaligned quasar 3C216  

3C216 is a compact steep spectrum (CSS) source whose milliarcsecond (mas) scale jet is misaligned with respect to the more extended, arcsecond scale structure. The source was observed on 14 February 1999 at 5 GHz (6cm) with HALCA, the western part of the European VLBI Network and the US NRAO Green Bank 43m telescope. The image has been restored with a 0.5 mas circular beam. A comparison with the radio/optical arcsecond scale structure, the ground only image and more information can be found at the investigators' web pages  

Image courtesy:  
I. Fejes, Z. Paragi, S. Frey (FÖMI SGO),  
R.W. Porcas (MPIfR),  
R.T. Schilizzi (JIVE),  
T. Venturi (IRA)  


3C279 

This 5 GHz image of 3C279 was made from an observation with the VLBA and HALCA. 3C279 was in 1971 the first "superluminal" source discovered, and the component on the right also appears to be moving away from the quasar core on the left at a speed greater than the speed of light -- an illusion caused by the speed of the jet and the fact that it is oriented towards our line of sight. The image has been restored with a circular beam.

Image courtesy:  
H. Hirabayashi, P. Edwards, J. Lovell, ISAS  
G. Piner, A. Wehrle, S. Unwin, JPL  

 

  The TeV gamma-ray source Mrk 421  

This 5.0 GHz image of the BL Lacertae object Mrk 421, was obtained from a VSOP observation with HALCA, seven telescopes from the European VLBI Network, and the US NRAO Green Bank 43m telescope. Mkn 421 was the first extragalactic source of TeV gamma rays to be discovered, and this VSOP observation is part of a study aiming to compare the inferred properties of the TeV (10^12 eV) gamma-ray beam with the radio jet. (Preprint available at astro-ph/9906202)

Image courtesy:  
B.G. Piner, S. Unwin, JPL  
A.E. Wehrle, IPAC/JPL  
P.G. Edwards, ISAS  
A.L. Fey, K.A. Kingham, USNO  


The jet of M87 

This 1.6 GHz (wavelength 18cm) image of M87, the central galaxy in the Virgo cluster, was made observation with the VLBA and HALCA. Click on the image to see a more detailed image showing a VLA (Very Large Array) image of the larger scale structure of M87 with the VSOP image shown as an inset.

VSOP image courtesy:  
M. Reid, CfA  

 

  The very high brightness source 1921-293  

This is the 5.0 GHz (wavelength 6cm) image of the quasar 1921-293, found to have a compact core with a diameter of only 0.1 milli-arcseconds, and a brightness temperature of 10^13 K. The image was made with HALCA and the Very Long Baseline Array (VLBA). The circle at the bottom left hand-side of the picture shows the synthesized VSOP beam used to make this image.

Image courtesy:  
P. Edwards, J. Lovell et al., ISAS  


The very high brightness source 1921-293 

This 1.6 GHz (wavelength 18cm) image of the quasar 1921-293 was made observation with the VLBA and HALCA. The circle at the bottom left hand-side of the picture shows the synthesized VSOP beam used to make this image.

Image courtesy:  
Z.-Q. Shen, S. Kameno, M. Inoue, NAO  
J. Lovell, P. Edwards, K. Fujisawa, ISAS  

 

  The Pearson-Readhead survey source 1803+784  

This 5.0 GHz image of the quasar 1803+784 is part of "Pearson-Readhead Survey from Space" program. Clicking on the image links you to the investigators' web page for this source, which shows a comparison with a ground-data-only image from the same observation.


The quasar 0836+710 

This 5.0 GHz image of the quasar was obtained from an observation on 7 October 1997 with the VLBA and HALCA. Clicking on the image links you to the investigators' web page for this source, which shows a comparison with a ground-data-only image from the same observation and gives more details of their analysis.

 

  The Pearson-Readhead survey source  0923+392  

This 5.0 GHz image of the quasar 0923+392 is part of "Pearson-Readhead Survey from Space" program. Clicking on the image links you to the investigators' web page for this source, which shows a comparison with a ground-data-only image from the same observation.


The high redshift quasar 2215+020  

The quasar 2215+020 lies at a redshift of 3.58, and this 1.6 GHz image of the quasar was obtained from an observation on 14 September 1997. Clicking on the image links you to the investigator's web page for this source, which shows a comparison with a ground-data-only image from the same observation and gives more details of the observation and data reduction.

 

  The gamma-ray source 1156+295  

A 1.6 GHz image of the quasar 1156+295 was obtained from a 2.7 hour observation using the ten-element Very Long Baseline Array (VLBA) and HALCA on 4 June 1997. The quasar, at a distance of 6.3 billion light years, shows a compact bright `core' and an extended milli-arcsecond scale `jet' on one side of the core. The standard physical model for this structure is that the core contains a massive black hole and that symmetric relativistic jets, powered by accretion onto the black hole, are ejected from this core. In most cases only the jet moving towards us is seen due to substantial Doppler boosting (see Science 281, 1825 (1998)).


The stationary component in 1548+056.  

This 1.6 GHz VSOP image of the quasar 1548+056 (at a distance of 9.3 billion light years) was obtained using telescopes in Australia, Japan and China and HALCA on 20 August 1997. The brighter component is the core and fainter feature is a component in the jet. Comparison with ground-only VLBI images reveals the jet component has shown no discernible motion over the last twelve years. This may arise if the jet is ejected from the core at an appreciable angle to the line of sight, with the stationary component corresponding to a region where the jet bends towards our line of sight and the radiation is enhanced by Doppler boosting (see Science 281, 1825 (1998)).

 

  The ultra-luminous high-redshift quasar 0014+813.  

0014+813 is one of the most luminous quasars known, lying at a distance of 13.6 billion light years. The 1.6 GHz image of 0014+813 shows a well-resolved core-jet structure. This observation was made with HALCA, six telescopes of the European VLBI Network and the NRAO Green Bank 43 m telescope (see Science 281, 1825 (1998)).


The super-luminal quasar 0212+735.  

A 5 GHz image of the quasar 0212+735 (about 12 billion light-years away) was obtained from a 14 hour observation on 6 September 1997 with HALCA and the VLBA. Components in the jet can be identified with components observed closer to the core in ground-only VLBI observations over the last 15 years. The extended feature on the left-hand side of the image was also evident 15 years ago but appears to have remained relatively stationary (see Science 281, 1825 (1998)).

 

VSOP image of 2021+614  VSOP Space VLBI image of 2021+614 at 5 GHz. The radio galaxy 2021+614 is one of 11 bright GPS (GHz Peaked Spectrum) radio sources investigated by our group with VSOP/HALCA. 2021+614 has a redshift of 0.2266. 

The Space VLBI observations were made on November 6th, 1997 (code VT906) with a 15-station ground-based array and HALCA (tracking stations: Goldstone, Tidbinbilla). The image was obtained using uniform weighting. The peak flux density is 426 mJy/beam and the rms noise level is about 0.75 mJy/beam. The restoring beam for the image is 0.498 x 0.232 mas (-53.1 degrees). 

The people involved in this project are:  
Schilizzi R.T., Langevelde H.J.; JIVE (NL)  
de Bruyn A.G.; NFRA (NL)  
Snellen I.A.G.; IoA Cambridge (UK)  
Tschager W., Miley G.K., Rottgering H.J.A.; Leiden (NL)  
Fanti C., Fanti R.; IRA Bologna (I) 


EGRET gamma-ray blazar 1633+382 at 6cm. This observation was made on 29 July 1997 with HALCA and the full VLBA. A maximum baseline length of about 250 million wavelengths was obtained, about a factor of 2 less than that achievable with VSOP, but still sufficient to separate the core (on the far left, or east) from a close-in jet component. 1633+382, at a redshift of z=1.807, is one of the most luminous and variable gamma-ray blazars, indicating that its relativistically moving jet is well aligned with our line of sight. The nearly east-west position angle of the inner jet differs by roughly 25 degrees from the direction of the jet in the early 1980s, which is also indicated by the most distant jet component in the northwest (upper right), about 100 light years from the radio core. Gamma-ray blazars such as 1633+382 are prime candidates for Space VLBI missions that have imaging capabilities at significantly higher resolutions than ground-based observations at the same frequency. 

The people involved in this project are: 
Jim Ulvestad (NRAO - Socorro) 
Tom Vestrand (University of New Hampshire) 
Greg Stacy (Louisiana State University & Southern University) 
John Biretta (Space Telescope Science Institute) 

VSOP image of 1633+382 

VSOP image of 3C446  VSOP Space VLBI image of 3C 446 at 6 cm. The quasar 3C 446 was observed on 2 December 1997 with an array consisting of HALCA, Ceduna (Australia), Mopra (Australia), Hartebeesthoek (South Africa), Shanghai (China), and Usuda (Japan). The (u,v) coverage had projected baselines of nearly 500 million wavelengths, giving resolution of about 0.25 mas in the East-West direction of the jet in 3C 446. 

At shorter wavelengths, the highly inverted core of 3C 446 is so dominant that it is difficult to see the inner part of the jet. However, this space VLBI observation at 6 cm reduces the strength of the core relative to the jet, enabling detection of the innermost jet component roughly 0.2 mas east of the core in this image. 

This image supplied courtesy of J.S. Ulvestad (NRAO-Socorro) 


PKS J2207-5346, a quasar at a redshift of 1.2, was observed as part of the VSOP AGN survey on 30 October 1997. HALCA and only two ground radio telescopes: Hartebeesthoek and Hobart, were used in this observation, resulting in a sparse (u,v) coverage. However, a good signal-to-noise image was still possible and, more importantly, the Earth-space baselines have allowed the core to be resolved and its brightness temperature to be measured for the first time. 

Data reduction and imaging by Jim Lovell (ISAS) and Chris Flatters(NRAO). 

VSOP survey image of PKS J2207-5346 


 
 
 
VSOP Space VLBI image of 1413+135 at 6 cm. The radio source 1413+135 is remarkable for a number of reasons; 1) it is 18 times more variable at 3.6 cm (X band) wavelengths than at 13 cm (S band), 2) it is one of the few (5) sources where radio absorption lines of (Carilli et al. 1992), CO, HCN and other molecules (Wiklind and Combes 1994) have been detected in absorption, and 3) it appears to be a young radio source. 

The accompanying figures shows the HALCA plus VLBA image (top) of 1413+135 at C band. The image has approximately 3 times the resolution of the VLBA only image(bottom), as expected. Notice the components of the jet visible to the south west, which are not resolved in the VLBA only image. The synthesized beam for this image is 2.05 x 0.47 mas with position angle -26.31 degrees. The entire image above is smaller than a single pixel of the HST image. 

For more images and details see the web page: http://www.gb.nrao.edu/~glangsto/1413/.

The people involved in this project are:  
Glen Langston, Toney Minter and Frank Ghigo (NRAO - Green Bank).


BL-Lac type object Mrk501 at 18cm. The observations were made on August 4th, 1997 (project V017d) with the following array: HALCA (8m); Goldstone (70m); VLBA (25m each). HALCA observed for 3h only, Goldstone for 5h and the VLBA for 8h except VLBA_SC (no data) and VLBA_MK (3h only). Green Bank was the tracking station. The data were correlated in Socorro and reduced in Bologna on a ALPHA workstation using the 15-APR-97 version of AIPS. 

The top image was obtained using uniform weighting. The  beam HPBW is 4.2 x 2.8 mas with a position angle of -3 degrees. The noise level is 0.7 mJy/beam and the peak flux density is 703.7 mJy/beam. The bottom image was obtained by applying  more weight to  the short baselines (ROBUST 0 in the AIPS task 'IMAGR'). The beam HPBW is 5 x 4 mas with a position angle of 0 degrees. The noise level is 0.6 mJy/beam. 

The people involved in this project are:  
G. Giovannini, L. Feretti, T. Venturi (Istituto di Radioastronomia - Bologna)  
W.D. Cotton (NRAO - Charlottesville)  
L. Lara (Instituto de Astrofisica de Andalucia - Granada) 

 


Active galaxy PKS 1519-273. At left, as seen with the ground-based VLBI network only (10 VLBA telescopes plus phased VLA). At right, with the addition of data from the HALCA satellite. This is the first VLBI image ever made using an orbiting radio-astronomy satellite. VSOPimage of 1519-273


Thanks to the PIs named above for allowing us to use their images