E-EVN science projects (2006-2008) Zsolt Paragi (JIVE), for the EXPReS project.

e-EVN science projects (2006-2008)

Zsolt Paragi (JIVE),for the EXPReS project

2008 June 16-17 7th e-VLBI Workshop, Shanghai Slide #2

What will e-VLBI offer for us one day? Several Gbps data rates/telescope, greatly increased sensitivity, “full” uv-coverage, flexibility…

What the e-EVN can do by the end of 2008:

• Open for users, regular observing sessions (10-12/year )

• Sensitivity and resolution comparable to disk recording

• Already more flexibility for rapid response science!

• Rapid feedback, you know if it works, you know what you observe…

• … enables quick decision about more observations (VLBI or other)

• Easy access, easy use – high level of PI support


Where are we now in capabilities…

Sensitivity and resolution in typical observations, 5 GHz

• e-EVN in 2007, 256 Mbps: 50 uJy/beam, ~6 mas

• e-EVN, 512 Mbps: 35 uJy/beam, ~6 mas

• e-EVN in 2008, 512 Mbps, 17 Jy/beam, ~6 mas (10 Jy, ~1 mas with Arecibo, Hh, Sh, Ur at lower data rates)

• Full EVN (no Ar), 1024 Mbps, 12 Jy/beam, ~1 mas

• VLBA, 512 Mbps, 30 Jy/beam, ~1 mas

• VLBA+GBT, 512 Mbps, 12 Jy/beam


… and how far can we go

Sensitivity

• Great 1 Gbps test results; 10 Gbps technology is available

• Max. 1 Gbps with current EVN; 4 Gbps upgrade is investigated

Resolution/imaging

• Sh tested in 2007; Ar, Hh, Ur 512 Mbps coming soon

• Besides do not we do science (just few days year) with a more global array including Australian and Japanese telescopes???

Flexibility

• Limited e-EVN ToO is possible on previously unscheduled dates, but flexibility is still an issue


e-VLBI operations and test results - 2008• Regular e-VLBI test observations in every six week (on average)

• 24h time is pre-allocated for science observation during tests

• Accepts normal and triggered proposals, more ToOs are supported

• Science operations (so far) at 1.6 and 5 GHz, max. 512 Mbps withCm, Ef - new, Jb2, Mc, On, Tr, Wb; Mh - possible

Tests (more by Arpad, Harro, Paul):

• With packet dropping near 1 Gbps

• Mixed data rate mode demonstratedAr, Hh, Sh, Ur can join science obs!

• Four-continent fringes


The two newest members of the e-EVN in 2008 (AJPoD by Stefanie Muhle)


Science results from the ‘Oz-demo’

ATCA, Mopra and Parkes observations at 512 Mbps, correlated at JIVE.

Target: the nearby supernova in the LMC, only visible from the South.

One of the breathtakingHubble Space Telescopeimages of SN1987A


And with VLBI…

Highest resolution image of SN1987Aso far (first VLBI!) – not bad for a three telescope array. Countours showsan earlier ATCA image.

Various fits to the data to measure the sizeof the expanding remnant.

Tingay et al., (in prep.)


e-EVN science projects in 2006/2007• Cyg X-3, 20 Apr/18 May 2006, 128 Mbps, Tudose et al.

• GRS1915+105, 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.

• J2020+3631 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 refereed journal papers:GRS 1915+105: Rushton et al. (2007), MNRAS 374, L47

Cyg X-3: Tudose et al. (2007), MNRAS 375, L11

Cyg X-3

Aftermath of a huge outburst-first detection of polarisation on VLBI scales in a microquasar

What PI’s really need is to be able tomonitor these events in (1) closely spacedmonitoring observations, (2) when theyhappen, not on fixed dates.


LSI 61+303 campaign: • 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 aninteracting pulsar wind source instead• MAGIC collaboration observations including e-EVN, VLBA, MERLIN, CHANDRA in October 2006

The MAGIC telescope and a view ofits surroundings in La Palma. It iscapable of detecting very high energygamma rays.

The telescope is operated by the MAGIC collaboration of 17 institutessince 2004.

http://wwwmagic.mppmu.mpg.de/


…and the results

• no ultimate answer on the nature of the binary yet• radio and X-rays originate from a different populationof electrons, but• there is indication for temporal correlation betweenX rays and gamma rays

Albert et al. (2008), Astrophys. J. (accepted),astro-ph/0801.3150


IGR 17303-0601 results:

M. Pandey, Z. Paragi, P. Durouchoux, H. Bignall, PoS(Dynamic2007)041

INTEGRAL source, with candidateoptical counterpart showing binary nature, and associated(?) radio sourcein NVSS.

e-VLBI confirms compactness, but measuredposition is inconsistent with optical coords.Not associated, radio source is not from a microquasar jet – likely background AGN.


CHARA and e-VLBI observations 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 interferometrystudies.

Algol is active from radio to the X-raybands, besides the optical variationsdue to regular eclipses.

Artist’s impression on the close binary systemfrom the web. The K-subgiant is the source ofradio activity.


The CHARA arrayThe CHARA array is located at Mount Wilsonin California, USA, and is operated by theCenter for High Angular Resolution for Astronomy

http://www.chara.gsu.edu/CHARA/


CHARA results

CHARA fringes before and after processing.

Resulted visibility amplitudes vs. baselinelength are shown below.

Fitted orbital parameters to the data, found geometry of the system.

Determined distance: 26.1±0.4 pc,Comparable or better accuracy than HIPPARCOS!

Paragi et al., submitted to PoS(Manchester MRU proceedings)

Csizmadia et al. (refereed paper in prep.)


Algol, 14 December 2006 e-EVN run:

• Simultaneous optical photometry and e-EVN obs. (5 GHz, 256 Mbps) during secondary minimum

• Source flared – total intensity and circular polarizationvariations consistent between WSRT and e-EVN data

• Flare emission ~2 mas offset from the CP peak

• Detected proper motion during the10 hours run –fitted orbital parametersof the AB close binary, but…

Dedicated observations of such flareswill be challenging even for e-VLBI

+


Supernovae: and old story with e-EVN • SN2001em was discovered on 15 September 2001 in UGC11794 galaxy (Pepenkova 2001).

• Redshift z~0.02 corresponding to a distance of 80~Mpc.

• 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 emissiondue 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

Garrett et al. (2005)


SN 2007gr ToO observations

• SN2007gr was discovered on 15 Aug 2007 with KAIT (CBET 1034); identified asType 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 supernovawithin the VLA error box

Paragi et al. (2007), ATel #1215


The first ATel messagefrom thee-EVN


Science projects in 2008• A number of exploratory runs

• Supernovae in IC694, member of the famous Arp299 galaxy merger system. PI Perez-Torres.

(MERLIN image from Antonis Polatidis)

... record breaking correlaton job!

• On 8-9 April 2008, the first real triggered observations: Cyg X-3 in an X-ray states change.

• Followed by a huge outburst and three ToO epochs, first e-EVN

observations outside the fixed dates.

• e-VLBI flexibility: could not do it with disks because stations were short of them!


Cyg X-3 giant flare (preliminary)

The Cyg X-3 puzzle; preliminary maps by the PI, Valeriu Tudose


What science would benefit from e-VLBI?

• Transients obviously, from quick turnaround mostly

• Surveys of a large sample of weak sources, detection not 100% guaranteed (but likely)

1) can follow up quickly the detected sources only, at other frequencies

2) big surveys not limited by recording media capacity

• Projects requiring dynamic scheduling

• Others???, e.g. support to VSOP-2 Survey, quick compactness check of highly variable sources (also in size!) before space VLBI observations?

• How could we best support X-ray and gamma missions, for example GLAST?

The highest redshift radio-detected quasar, withthe EVN at 1.6 GHz - CSO at the edge of the visible Universe! (Frey et al. 2008)

J1427+3312, z=6.12


Synergy with other (e-)instruments

• e-MERLIN will be complementary in resolution to the e-EVN; short spacings

• LOFAR will be an exceptional instrument for finding new transients

• Wide FoV focal plane array considered for the WSRT - could also serve as a trigger instrument

LOFAR (up) and DIGESTIF on the WSRT (left); from Astron web

www.gsfc.nasa.gov

GLAST


Finishing thoughts...

• As Steven pointed out yesterday, e-VLBI is technologial pathfinder to SKA.

• Specific developments in EXPReS definitely make the e-EVN an SKA pathfinder.

• But do not think just the technology! We are looking for new ways of doing VLBI research, especially in the area of transients, which could soon transform our field considerably.

• e-EVN matured a great deal during the first two years of EXPReS, now it is time to harvest the results.

• EXPReS eVSAG (e-VLBI Science Advisory Group) will address this within a few days.

E-EVN science projects (2006-2008) Zsolt Paragi (JIVE), for the EXPReS project.

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Transcript of E-EVN science projects (2006-2008) Zsolt Paragi (JIVE), for the EXPReS project.