e-VLBIe-VLBIe-EVN: a SKA pathfinder for high e-EVN: a SKA pathfinder for high resolution probing of the radio resolution probing of the radio
continuum sky continuum sky
Zsolt Paragi, JIVEZsolt Paragi, JIVE
Huib van Langevelde, JIVE & LeidenHuib van Langevelde, JIVE & Leiden
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Outline
•Progress with e-VLBI•Technological progress•Introducing EXPReS & NEXPReS•Operational service•Scientific achievements
•Probing the continuum universe•Synergy with other pathfinders•Continuum surveys with VLBI
•e-VLBI and the future•VLBI in the SKA era•evolving VLBI
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Current EVN
•EVN consortium with 20+ possible antennas• Ef, Mc, On, Jb, Nt, Tr, Wb, Sh, Ur, Hh, Ar, Mh, Ys, Sv, Ro, Ku, My, Wz, Sm, Ny, Ka
•Ran by up to 14 different organizations•And 12 more antennas for “Globals” with NRAO
•Covering range of frequencies•Workhorse frequencies 18cm, 6cm, •Also available: SX, 5cm, 1.2cm•And at limited stations 90cm, 21cm, UHF, 50cm, 2cm, 0.7mm
•Reaching mas resolutions•From 15mas for 1.4 GHz EVN (can add MERLIN for brightness sensitivity)•To 1 mas at 5GHz with Asian, African or American baselines
•Sensitivity of 5μJy in 8hr at 1.4 GHz•Combination of Big Antennas and 1 Gbps bandwidth•Big antennas also vital for spectroscopy (mJy sensitivity)
•Operational approximately 60 days/year•3 sessions augmented with e-VLBI once a month
Irbene 32mIrbene 32m
Miyun 50mMiyun 50m
Kunming 40mKunming 40m
ZelenchukskayaZelenchukskaya
SvetloeSvetloe
Yebes 40mYebes 40m
BadaryBadary
Sardinia 64mSardinia 64m
•Current correlator•1024 custom chips•16x16 baselines, 0.25s
QuickTime™ and aCinepak decompressor
are needed to see this picture.
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Turned into e-VLBI
•PC based recording•Also allows Internet transmission•Started with a pilot in 2004
•And was boosted with EXPReS•Retrofit correlator to work real-time•Help solve last mile problem at telescopes
•Work with NRENs on robust connectivity
•Push to 1024 Mb/s limit•Change of VLBI culture in EVN
•Made use of Geant network•And SURFNet in NL•LOFAR synergy•very cost effectively...
• Connections work great!• often dedicated light paths• Use optimized protocols• Closed feedback loop
makes e-VLBI more robust
EXPReS was concluded in Mar 2010
Successful NEXPReS proposal kicked off in July 2010
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Addressing issues:
•Correlator passes are a problem•Not a perfect correlator •Partly remedied by software correlator
•Not all telescopes connected•Noto/Sardinia•Newly added Russian telescopes•Global baselines with VLBA
•Reliable operations•Of all components in the chain
•Could be addressed by simultaneous recording!
•And get the best of both worlds!
•Correlate in real time what you can,
•Correlate later what you need
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NEXPReS: EXPReS follow-up
•Main objective to introduce transparent caching •Lift distinction between VLBI and e-VLBI operations•Continue collaborations with NRENs
• Bandwidth on demand allocation
•Common technology questions with LOFAR and SKA• Broadband storage
•15 partners (cf. 19 in EXPReS)•Of which 3 choose not receive funds from EC•Good mix from astronomy-networking-HPC communities•High level of partner-contributed effort
•Kicked off in September at EVN symposium•Had to fit project within 3.5 M€ envelope•Relatively painless, good progress
•Continuity for e-VLBI operations•Keep key expertise, discussion on shaping e-VLBI in eVSAG•And assures continued connectivity in collaboration with NRENs
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e-EVN operational Disk-based network hours roughly constant
ToOs: half (49.5%) of the total e-EVN observing time in 2010 so far.
•Operational facility•Guaranteed 10 x 24h per year
•Flexible ways to get into e-VLBI•Request e-VLBI for fast response
•Or for triggered proposals•Short requests <2hr•Target of Opportunities•Or just because you prefer e!
Producing VLBI results on timescales comparable to other instruments
Demonstrated capability of initiating new observations based on e-EVLBI results within a day/days!
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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VLBI Future
•Unique science: long baselines and high frequencies•Keep up with EVLA/MERLIN sensitivity
•Going for 4Gbps in 2011
•Follow up LOFAR, MeerKAT results•Even in the SKA era•Science case has been developed
•http://www.evlbi.org/publications/publications.html
•Better images? More telescopes!•MeerKAT, African array, Azores, eMERLIN
•100-fold bigger correlator
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VLBI in the SKA era
•Unique science case for VLBI•Definitely during SKA phase I and II
•Global baselines northern hemisphere
•Based on eVLBI advances•Sensitivity, Robustness, Flexibility
•Lots of overlap with SKA technology•Benefit from digital components•And even antennas•And processing software•Synergy with other SKA pathfinders
•Requires a Global approach•With a common technology roadmap
•e-VLBI could be the vehicle for doing that
•Some activity started with VLBA closing threat
Recent (e-)EVN results (disk and e-VLBI, some with VLBA follow-ups)
• First truly global e-VLBI science paper: PMN J0948+0022
• Transients: XTE J1752-223
MAXI J1659-152
A new gamma binary: HESS J0632+057
• Starforming galaxies vs. AGN:
Arp 299A
Low-redshift analogs of Lyman-break galaxies
• The less-known faint source population:
Is FIRST J1218+2953 a dark lens?
Mistery of the highest redshift quasars
A new double AGN (from last month)
• First Fermi-detected narrow-line AGN
• Longest baseline Mopra-Yebes, 1248 km
• Very compact, slightly polarized core with weak jet
To appear next week in Astronomy and Astrophysics
Strongly decelerating jet in XTE J1752-223
EVN and the VLBA efficiently work together.Yang et al. (2010), MNRAS 409, L64
MAXI J1659-152
Black hole candidate, first VLBIdetection with the e-EVNParagi et al.(2010) Atel#2906
The shortest period black hole binary with a period of 2.4hKuulkers et al. (2011), arXiv:1102.2102
Phase-reference check source found in the first e-VLBI run, before and after additional phase-selfcal. Note -15 degrees DEC
RXTE lightcurve a HR diagram (from Tomaso Belloni)
VLBA follow-up at higher resolutionCheck source (now resolved) above, target belowDid not find the expected bright ejecta almost always seen in BH binaries during full state transition
HESS J0632+057, -ray BH binary candidate
Moldon, Ribo & Paredes (2011), ATel #3180
• VERITAS and MAGIC reported increased activity at >200 GeV between 7-9 Feb. 2011. EVN e-VLBI observation on 15 Feb. 2011 resulted in first VLBI detection
• Radio source is within 14 mas of the Be star (MWC 148) optical position TeV emission produced <20 AU of the star, strongly suggesting the presence of a compact object in close orbit
A spectacular supernova factory in Arp299A
• IC694 (=Arp299A) is a Luminuous Infrared Galaxy that hosts an intense burst of starformation leading to numerous explosions of core-collapse SNe. Many of these are hidden by dust at optical wavelenghts
• Closely spaced EVlN e-VLBI observations show a number of new radio sources appear. There are 26 radio sources in the central 150pc that are most likely young radio SNe or supernova remnants. Three sources have unusual properties, they are likely influenced by the local ISM
• The results support for a recent (10–15 Myr) instantenous starburst in the nuclear region
• Further monitoring will allow to estimate the supernova rate in this system, which will further help to constrain the starformation rate and the initial mass-function and starburst scenarios at work
Perez-Torres et al. (2009). A&A 507, L17
Latest: 1.7 GHz e-EVN data show the long missed AGN!Perez-Torres et al. (2010), arXiv:1012.4744
Local analogs of Lyman Break Galaxies
• LBGs are an important phase in galaxy formation and evolution
• Are these nuclear starbursts or there is an LLAGN as well?
• Hard to detect obscured AGN at high redshift
• Selected a sample with similar properties but at low-z
Project initiated by Roderik Overzier, MPAEVN data analised in JIVE by Rachael Alexandroff, Princeton Univ.
• BPT plot puts these sources in the region of “starburst/AGN composites”• Other line ratio diagnostics give differing results• Evidence for low luminosity AGN?
SDSS J015028+130858 SDSS J092159+450912
• 2 out of 4 sources detected with the EVN at 1.6 GHz at 6-7 level• 1 out of 8 sources tentatively detected at 5 GHz at ~<5• recovered flux density ~10% VLA• L ~1029 erg/s/Hz: too luminous for individual SN/SNe• sizes 20-40 mas, Tb = 13x105 K, bit high for starformation• spectral indices steep, < 0.3 (5 GHz non-detection)=> does not look like AGN either
Dirty maps of the detected targets
The highest-redshift UniverseJ1427+3312
z=6.12
EVN, 1.6 GHz
EVN 5 GHz
Frey et al. 2008A&A 484, L39
• When and how the first quasars were born? z>>4 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?
• J1427+3312 shows CSO characteristics: double morphology, steep spectrum, resolved components
A young radio source caught in action of forming?
• VLBI mini-survey: are there more, similar sources?
• Looked for very high-z compact SDSS sources with compact FIRST counterprt =>all detected with VLBI
• Sources mostly have steep spectra, and low Tb => not beamed, these
are most likely young CSOs as well
• However, there is one flat spectrum, and another, source has clearly
one-sided structure; but they too have Tb ~ 109 K
Frey, Paragi, Gurvits, Cseh, Gabanyi 2010, A&A 524, A83
2009 Nov. 18 EXPReS Final Review
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A Dark Lens candidate
• Russell et al. (2008, ApJS 179, 306) optical arc discovered in HST image -without apparent lensing Galaxy
• Ryan et al. (2008, ApJ 688, 43) Nearby FIRST radio source may belong to the lensing object, not seen in the optical image (but note 1 error in registration of positions)
• If the lensing scenario is correct:is the lens a heavily obscured galaxy, or an object dominated by dark matter?
• 1.6 and 5 GHz e-EVN observations in 2009
FIRST J121839.7+295325
ARCHot pixel?
HST WFPC2 image
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VLBI results: AGN activity
FIRST J1218+2953
Brightest part atfull resolution
• Components have steep spectra, and structure indicates CSS/MSO type morphology in the tapered map • Missing some extended flux, but most of the WSRT flux density is recovered with VLBI within 1 arcsecondthis is not a lensed image
Heavily obscured galaxy, not dark matter lens
Frey et al. 2010, A&A 513, A18
Binary black holes
See also SDSS J1536+0441
Bondi, Perez-Torres (2010), ApJ 714, L271
• Supermassive BH binaries are expected as a result of galaxy mergers but so far only a few known
• SDSS J1425+3231 is known for its double-peaked narrow optical emission lines (Peng et al. 2010)
• e-EVN observations on 25 Jan.2011Frey, Paragi, Gabanyi and Tao
Conclusions
• Exciting science results have been produced with
real-time VLBI
• More and more (future SKA) users discover the advantages of the fast turnaround time and more flexible scheduling
• Some of the potentials have not been fully explored yet, but we are ready to take the next steps! (triggering from SKA
precursors; large FOV VLBI surveys etc.)
• SKA will need the long baselines to adress some of the questions, but even 10 mas will not be enough in some cases – there is future for VLBI
e-VLBI rocks
Happy PI #2
“All hail to e-VLBI”
Happy PI #1
"Thanks for getting the pipeline ready
this quick - eVLBI just rocks!”
Happy PI #4
“That sounds super
quick to me :-)”
Happy RnD boss "Wow, so many Atels! Fantastic.
3:0 for e-VLBI I would say."
“Holy antipodes, Batman!”
Well-known VLBI astronomer on EVNtech, after the announcement of the
detection of real-time fringes between Mopra (AU) and
Jodrell Bank (UK).
Happy PI #3
“Yes, this is probably one of
the most beautiful dataset
I've ever seen. :)”
