The eEVN, a realtime VLBI instrument

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The e-EVN, a realtime VLBI instrument

• Zsolt Paragi (JIVE),
• for the EXPReS project

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http//www.evlbi.org/
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The path to higher sensitivities
16 station MarkIV correlator at JIVE. Tape
operations used to limit data rate (256 Mbps per
head), and were less reliable. http//www.jive.nl
Mark5a recording since 2004 robust 1024 Mbps
operation allows direct transfer over
the Internet ? Realtime e-VLBI
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What is EXPReS?

• EXPReS Express Production Real-time e-VLBI
  Service
• Three year project, started March 2006, funded by
  the European Commission (DG-INFSO), Sixth
  Framework Programme, Contract 026642
• Objective to create a distributed, large-scale
  astronomical instrument of continental and
  inter-continental dimensions
• Means high-speed communication networks
  operating in real-time and connecting some of the
  largest and most sensitive radio telescopes on
  the planet
• http//www.expres-eu.org

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From telescopes to correlator
Geant2
SURFNet
JIVE
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What will e-VLBI offer for us one day?
Several Gbps data rates/telescope, two orders of
magnitude better sensitivity, full uv-coverage,
flexibility
What the e-EVN can offer today

• Comparable sensitivity and resolution to the
  EVN, but
• More flexibility for rapid response science
• Rapid feedback, helps reliability, and of course
  quick results
• enables quick decision about follow-up
  observations (VLBI/other)
• Easy access, easy use high level of PI support

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Comparing numbers

• Sensitivity and resolution in typical
  observations, 5 GHz
• e-EVN in 2007, 256 Mbps 50 uJy/beam, 6 mas
• e-EVN in 2008, 512 Mbps, 10 uJy/beam, 1 mas
  (including ShAr)
• e-EVN in early 2009 Ef, On, Tr, Wb full 1024
  Mbps capable
• Full EVN (no Ar), 1024 Mbps, 12 uJy/beam, 1 mas
• VLBA, 512 Mbps, 30 uJy/beam, 1 mas
• VLBAGBT, 512 Mbps, 12 uJy/beam

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Real-time operations

• Data quality control with various software tools,
  available through the Web

• On-the-fly clock updates, without
• interrupting correlation job

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Latest milestones

• Succesful observing schedule change for two
  telescopes on-the-fly.
• Ultimate goal is fully flexible VLBI operations!
• Besides Jb and Cm, 1 Merlin outstation now
  routinely included.
• Additional short spacings are extremely valuable.
• 19 November 2008 three telescopes full 1024 Mbps
  capable
• 25 March 2009 Ef, On, Tr, Wb 1024 Mbps (Jb soon)

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IYA2009 opening ceremony

• Real-time demonstration of a global e-VLBI array
  in action
• First realization of on-the-fly pipeline imaging

Manual imaging of the same data
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IYA2009 100 hours of astronomy

• New record in incoming data rate
• to the correlator, gt6 Gbps

Yebes40m!
Paul Boven cacti for 3 April 2009
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EVN Mp, Ho
EVN
EVN with Sh
Sh to Mp, Ho
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Mp-Sh
Ho-Sh
Mp-Ho
EVN
EVN-Sh
EVN-Mp, Ho
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Full power of the EXPReS e-VLBI array
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e-EVN science projects in 2006/2007

• Cyg X-3, 20 Apr/18 May 2006, 128 Mbps, Tudose et
  al.
• GRS1915105, 20 Apr 2006, 128 Mbps, Rushton et
  al.
• LSI 61.303, 256 Mbps, 26 Oct 2006, Perez-Torres
  et al.
• Algol, 26 Oct/14 Dec 2006, 256 Mbps, Paragi et
  al.
• Calibrators near M81, 14 Dec 2006, 256 Mbps,
  Brunthaler et al.
• INTEGRAL microquasar candidates, 14 Dec 2006,
  Pandey et al.
• double header run, 15 XRBs, 29 Jan 2007,
  Rushton Spencer
• Calibrators, 21 Feb 2007, 256 Mbps, Tudose et
  al.
• J20203631 microquasar candidate, 28 Mar 2007,
  256 Mbps, Martí et al.
• Cyg X-3, 12-13 Jun 2007, 256 Mbps, Tudose et al.
• Stellar maser search, 22-23 Aug 2007, 32 Mbps,
  Langevelde et al.
• INTEGRAL source redo, 6-7 Sep 2007, 256 Mbps,
  Pandey et al.
• Type Ib/c SN 2007gr, 6-7 Sep 2007, 256 Mbps,
  Paragi et al.

First year of EXPReS proved that the e-EVN offers
better opportunities for PIs to organise
multi-waveband projects with VLBI
participation. Two early examples, with
interesting applications
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LSI 61303 campaign

• MAGIC collaboration
• PI for radio monitoring Miguel Angel
  Perez-Torres, IAA, Granada, Spain
• Binary XRB system, also source of very energetic
  gamma rays
• What is the source of these? Earlier hypothesis
  microquasar jet.
• Recent VLBA observations (Mioduszewski et al.)
  suggest an
• interacting pulsar wind source instead
• MAGIC collaboration observations including
  e-EVN, VLBA, MERLIN, CHANDRA in October 2006

The MAGIC telescope and a view of its
surroundings in La Palma. It is capable of
detecting very high energy gamma rays. The
telescope is operated by the MAGIC collaboration
of 17 institutes since 2004. Image from MAGIC
webpage http//wwwmagic.mppmu.mpg.de/
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and the results

• no ultimate answer on the nature of the binary
  yet
• radio and X-rays originate from a different
  population
• of electrons, but
• there is indication for temporal correlation
  between
• X rays and gamma rays
• Albert et al. (2008), Astrophys. J. (accepted),
• astro-ph/0801.3150

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Joint optical and radio interferometry observation
s of Algol
Algol is one of the most famous variable stars,
also known as beta Persei.
It is very nearby, only 26 parsecs away, ideal
for optical/radio interferometry studies. Algol
is active from radio to the X-ray bands, besides
the optical variations due to regular eclipses.
Artists impression on the close binary
system from the web. The K-subgiant is the source
of radio activity.
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The CHARA array
The CHARA array is located at Mount Wilson in
California, USA, and is operated by the Center
for High Angular Resolution for
Astronomy http//www.chara.gsu.edu/CHARA/
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CHARA results CHARA PI Szilard Csizmadia, then
at Konkoly Obs., Budapest, Hungary
CHARA fringes before and after processing.
Fitted orbital parameters to the data, found
geometry of the system. Optical interferemetry
leaves 180 degrees ambiguity in the angle of te
ascending node.
Inner orbit 1000x magnified
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Algol, 14 December 2006 e-EVN run e-EVN PI
Zsolt Paragi, JIVE

• Simultaneous optical photometry and e-EVN obs.
• (5 GHz, 256 Mbps) during secondary minimum
• Source flared in radio, complicates astrometry,
  but
• Algol motion is clearly detected during the run
  e-EVN
• resolves the ambiguity in the angle of the
  ascending node.
• Optical and radio interferometry are
  complementary
• techniques.
• Using joint CHARA/e-EVN results, numeric
  simulations
• of the Algol system by Tamas Borkovits, Baja
  Astron.
• Obs., Hungary

Csizmadia et al. submitted to AJ
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Two years of a microquasar Cyg X-3
PI Valeriu Tudose, Univ. Amsterdam (recently
moved to Astron, Netherlands)
Aftermath of a huge outburst -first detection of
polarisation on VLBI scales in a
microquasar Where IS the core? Lack of
regular phase-referencing observations before.
Tudose et al. (2007), MNRAS 375, L11
Increased flexibility of e-EVN brings the
possibility to more frequently monitor highly
variable Galactic black holes (or BH candidates)
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• Since then identified core and provided unique
  data for accretion state classification
• Image courtesy Valeriu Tudose

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Chasing high-energy transients
AGILE transient in the gamma-Cygni region on 27
May 2009. e-EVN detects a radio source
originally believed to be the counterpart. Trejo
et al. (2008) Paragi et al. (2008)
INTEGRAL source IGR 17303-0601, with candidate
optical counterpart showing binary nature, and
associated (?) radio source in NVSS. e-EVN not
associated, likely background AGN. M. Pandey,
Z. Paragi, P. Durouchoux, H. Bignall,
PoS(Dynamic2007)041
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Supernovae and old story with e-EVN
Garrett et al. (2005)

• SN2001em was discovered on 15 September 2001 in
  UGC11794 galaxy (Pepenkova 2001).
• Redshift z0.02 corresponding to a distance of
  80Mpc.
• Filippenko and Chornok (2001) classified it as
  type Ib/c, most likely Ic.
• Exceptional radio and X-ray luminosities
• (off axis GRB, developing late radio emission
• due to jet break?),
• Not quite a 1 mJy radio source
• EVN observations Cm, Jb2, On, Tr, Wb (128Mbps),
  Arecibo 300m (64 Mbps)
• at 18cm, on 2005 Mar 11
• Tentative detection (4.5 ?) of the first real
  faint target with e-VLBI
• Paragi et al. (2005), MSAIt 76, 570

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SN 2007gr ToO observations

• SN2007gr was discovered on 15 Aug 2007
• with KAIT (CBET 1034) identified as
• Type Ib/c.
• Distance is about 7.3 Mpc, 10x closer than SN
  2001em was.
• VLA discovers 610 microJy radio source
• (Soderberg 2007)
• e-EVN observations Da, Jb2, On, Tr, Wb
  (256Mbps), at 6cm, on 2007 Sep 6-7
• Firm detection (5.6 ?) of the supernova
• within the VLA error box
• Paragi et al. (2007), ATel 1215

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Producing VLBI results on timescales comparable
to other instruments
Demonstrated capability of initiating new
observations based on e-EVN results within a
day/days!
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The latest news from e-EVN (still hot!!!)

• Compact SNRs in Arp299
• PI Miguel Angel Perez-Torres

WSRT/e-EVN resolves the mystery of Hannys
Voorwerp Jozsa, Rampadarath, Garrett et al.
? (image removed from public version of
this presentation)
AGN activity
SS433 in outburst, PI V. Tudose
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The high-redshift Universe
J14273312 z6.12

• PI Sandor Frey (FOMI SGO, Hungary)

• When and how the first quasars were born?
• zgtgt4 population is faint and completely missed in
• flat spectrum, flux limited surveys.

• What is the fraction of gravi-
• tationally lensed sources at the
• highest redshifts?
• Differentiate between starburst
• and QSO activity ? needs a
• resolution of 10 mas or better
• and very good sensitivity at the
• moment only top of the iceberg
• seen.
• Long-baseline configuration of
• SKA!

EVN 5 GHz
EVN, 1.6 GHz
Frey et al. 2008 AA 484, L39
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• J14273312, the highest-redshift radio quasar
  shows CSO characteristics
• double morphology, steep spectrum, resolved
  components
• A young radio source caught in action of forming?
  Will be possible to tell from
• VLBI monitoring observations, that can measure
  the source expansion rate.
• A great potential target to detect hydrogen at
  z6.12 with the SKA!
• VLBI survey are there more, similar sources? How
  to find them?
• Experience from DEVOS look for (high-z) compact
  SDSS sources with radio detection (Frey et al.
  2007, AA 477, 781)
• EVN/e-EVN survey so far 100 detectin rate!
  e-EVN used for pre-selection but will help the
  highest sensitivity observations as well, because
  it is not limited by disk space.

e-EVN 1.6 GHz 10-11 Feb. 2009
J13000118 z4.61
J16144640 z5.3
Images from pipelined data the e-EVN is a
powerful, fast-response detection instrument
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e-EVN run starting tomorrow, 21-22 April

• Follow data inflow and fringes real-time through
  the web
• http//www.jive.nl/correlator/statusmonitoring/dsm
  .html
• http//www.jive.nl/correlator/corstat/corstat.html
  
• On the menu
• Radio source near a dark lens part of the dark
  lens, or lensed image itself?
• M33 X-8 ULX near the centre of the gx
• PMN J09480022 a narrow-line Seyfert galaxy
  recently detected by Fermi
• e-EVN observations part of a global campaign
• ToO response to a spectacular M82 transient
• Two more target of opportunity proposals are
  foreseen in April 2009 the EVN has never seen
  this many ToO projects

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M82 transient

• This is happening now!
• Within a few days of reporting the discovery, the
  e-EVN is looking at M82 (session 21-22 Apr 2009,
  starting tomorrow)
• 42.8259.54 100 mJy in 2008, best fit with
  exponential decay SN or more exotic transient?

VLA-B 8.4 Ghz 2007 Oct 29

• Near the gx centre unrelated to known X-ray
  sources
• Note SKA will need baselines of several 1000 km
  to study the expansion of SNe and other
  transients in nearby galaxies

VLA-C 22 GHz 2008 May 3
VLA-B 22 GHz 2009 Apr 8
arXiv0904.2388 Brunthaler et al. 2009
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Conclusions

• The e-EVN routinely operates with data transfer
  (from some telescopes) exceeding 1 Gbps 1000
  Mbps over thousands of kilometers, and is going
  towards multi-Gbps data rates that will be
  required for the SKA.
• There is a new community forming that will take
  advantage of a flexible, real-time VLBI
  instrument,
• pioneering scientific applications of a large
  resolution SKA. Before SKA, exciting
  opportunities to explore
• new areas jointly with e-Merlin, LOFAR,
  WSRT/Apertif.
• The EXPReS e-VLBI array has demonstrated the
  feasibility of operating a global real-time
  instrument over the Internet.