The LOFAR Super Station in Nancay Philippe Zarka, Michel Tagger, Laurent Denis, Julien Girard, Cyril Tasse the LSS team from Nançay Observatory The consortium FLOW and the LSS teams from Obs. Paris LESIA/ GEPI/LERMA, LPC2E, PRISME, OCA, CEA, IAS, IRAP, CRAL In coll. with IRA/Kharkov 

The LOFAR station in Nançay : FR606 Préparation Terrain Prochaines étapes, nivellement, installation des antennes 

How to go futher ? • ARTEMIS • AARTFAAC • Late Dark Ages • LWA... LSS = a super-high sensitivity extension to LOFAR and standalone instrument 

« Back-end » Super station concept LBA HBA LBL HBA LBA LSS = phase array & interferometer f ∈ [15-80] MHz ⊃ LBA LSS ~ 150-200 m Add 96 sub-arrays of N~10 antennas analog-phased ˠ to LBL input Phasing + summation 

What LSS can bring LOFAR Station in Nançay 

LSS More high sensitivity (10-20x) long baselines What LSS can bring 

EoR LSS + unused stations LSS = 2nd LOFAR core LSS What LSS can bring 

Short baselines (< ∅ station) What LSS can bring 

Short baselines ~ ∅ station HBA LBA Bmin 

A large stand- alone instrument sensitive down to ~15 MHz What LSS can bring 

The antenna CODALEMA LOFAR LBA LWA « Big Blade » GURT NEC simulations + optimisation of the geometry for a large FoV and high sensitivity over 15-80 MHz band LWA-­‐like  «  Fork  »  +  ground  screen 

The antenna 10 100 1000 R (!1!) LWA Fork with the transverse rod LWA Fork without the transverse rod Antenna Input Impedance Radiation Resistance -600 -400 -200 0 200 400 600 800 1000 X (!1!) LWA Fork with the transverse rod LWA Fork without the transverse rod Antenna Input Impedance Reactance ! ! ! ! type 1!! ! ! ! ! ! type 2 Color legend:! ! Red! ! ! ! ! ! ! Blue Beam Patterns ! ! ! H-plane! ! ! ! ! ! ! E-plane 20 MHz 80 MHz Antenna Input Impedance Option #2: Original development from optimization studies •  Numerical simulations carried with NEC (« Numerical Electroma •  Simulated variations of radiator geometry and of EM environm antennas. Criteria to define the « best » antenna for the LSS For the mini-array: (with analog phasing) ‛ Smooth beam pattern without gain drops or sidelobes in/at specif ‛ Nearly constant gain from zenith to low elevations (in E & H pla ‛ Quick directivity collapse for elevations ! 30° to reduce RFI con ‛ Broadband characteristics over the [20-80] MHz Considered geometrical parameters oject (96 dual pol) Drift scan compared to sky predictions from LFmap (Polisensky, 2007) LFmap Prototype ! Optimized radiator: LWA-like « thick » V-shape antenna EM Simulation 2 96 High Band Ant. 96 Low Band Ant. 96 Free inputs 96 LBA 30-80 MHz e back-end ow array) layout rences therein 

The amplifier • Nançay microelectronics design • GURT design • Subatech design Amplificateur «Na Tests labo en cou Tests ciel à veni Une Super Station Lofar à Nançay - Comment? Une antenne active et ..... des câbles (5.5 kms) Un partenaire expérimenté Un amplificateur performant Choix définitif à finaliser 

Observation of Jupiter with NDA & LSS-1/GURT 9/10/2011 Une Super Station Lofar à Nançay - Une antenne active et ..... des câbles (5.5 kms) Un partenaire expérimenté Un amplifica 

GDAM-GLSS ~ 18-19 dB Sgal = 2kTgal/A Sjup = 2kTjup ωjup/AΩantenne 㱺 (Sjup / Sgal) = Tjup ωjup/Tgal Ωantenne 㱺 (Sjup / Sgal)DAM ----------------------------- = ΩLSS/ΩDAM = GDAM/GLSS (Sjup / Sgal)LSS 

x x = estimation NEC4 (JG) → Directional Gain of LSS antenna Aeff = λ2/3 to λ2/4 

The sub-array & the phasing system • N = 19 antennas • Sensitivity, low secondary lobes, ease of analog phasing LSS 09 décembre 2011 antation mini-réseau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basse fréquence Optimisation des lobes de réseau Système simple, éprouvé, caractérist étudiées Etude éventuelle solution alternative 2 partenaires 

The distribution of LSS sub-arrays • Performances, terrain constraints • 14000 cables, 35 km LOFAR N! !"#$%$&'()*$+++$,'-(*$ $$. $$$$$,&$$$$+++$$$/&$$$$$012$ !"#$%&'()*+),-").)/0"-(&).)1 ,#2) 3)4++),) !"#$%$&'()*$+++$,'-(*$ $$. $$$$$,&$$$$+++$$$/&$$$$$012$ !"#$%&'()*+),-").)/0"-(&).)1 ,#2) 3)4++),) !"#$%&' !"#$%&'(" )"*+,-.&$/0+"1 67&"8'"98$+" )":%+%&"5-20;9 80+.7'7&6"5'"2< >$?'2"@0+2/0+6 )"B&$+6#0&;$/0 D'8$/?'6"4E"FG *+# 

Test receiver • 196 MHz sampling • 3 sub-arrays in input • Full correlation matrix 

Control-Command-Pointying-Dialog with LOFAR 19/07/2011 AC & CT 1 (visite AC et CT en Hollande, le 17/18 Mai 2011) Mode international Parset file Fichier de configuration lss Parset file lss LCU LOFAR Nançay Hollande LCU - LSS + message ‘start’ Process en attente du message ‘start’ Process en attente du message ‘start’ + message ‘start’ Pointage numérique Pointage analogique L’intégration reste valable même si le soft LOFAR évolue, l’interaction étant faite uniquement par l’échange d’un fichier et d’un ‘top’ départ. Mode standalone Parset file lss LCU LOFAR Nançay LCU - LSS + message ‘start’ Process en attente du message ‘start’ Process en attente du message ‘start’ Pointage numérique Pointage analogique + message ‘start’ Parset file lss Configuration de l’observation 

LSS as a large standalone instrument 

LSS science • Exoplanets & Binary/Eruptive stars Existence and characteristics of radio emission, Star-Planet interactions, comparative (exo-)magnetospheric physics. → LSS + LOFAR : sensitivity, RFI+ionosphere mitigation, duty-cycle, LF (// UTR-2) 

• Pulsars & Rotating radio transients (RRATs) Detection especially at low frequencies, physics of the environment of compact objects, nature of RRATs, giant pulses, possibly planets around pulsars, structure of the ISM via propagation effects → LSS standalone : sensitivity+FoV = discovery machine!, LF LSS science 

• Structure of the Galactic ISM Extended objects, magnetic field, turbulence+cutoff, RRLs → LSS LOFAR : short baselines, LF 3° VLA 74 MHz LOFAR 49 MHz (base maximum = 25 km) LSS science 

• Cosmology and Galaxy formation Signature of pre-EoR dark ages, history of Universe formation (AGN at z<1, star formation in nearby galaxies, clumps up to z=2...) → LSS standalone : sensitivity, calibration → LSS + LOFAR : high-sensitivity VLBI, polarization CMB âges sombres premières sources réionisation premières galaxies LSS science 

• The impulsional Universe Serendipitous/blind/exhaustive exploration of the impulsive Universe (ideal in Low-Frequency (LF) radio due to absence of photon noise); time & frequency scales of (dispersed) pulses, nature of emitters (GRB, CR, neutrinos/Moon, discovery...) → LSS standalone + dedicated backend : sensitivity, TAB+ mode, extended TBB, duty cycle LSS science 

• Transient Luminous Events (TLE) in the Earth and planetary atmosphere Radio exploration of counterparts of sprites and other TLEs ; origin, distribution / dynamics over center France, time & frequency scales, physical mechanisms → LSS standalone : sensitivity, TAB+ mode, extended TBB, duty cycle LSS science 

+ Solar system physics : ionospheric scintillations/ opacity, Jupiter DAM+DIM, Solar bursts, Space physics (IP scintillation, RADAR...) structures from decametric observations n. ” - n - of Fig. 1. Example of dynamic spectra from UTR-2 from the time series of July, 13 2002. Examples of the drifting structures studied here are indicated by arrows. 7. Summary and perspectives All the previous examples, based on real observations by using existing radio telescopes, suggest that this still quasi-unexplored part of the spectrum, which lies below  50 MHz; can now be successfully studied with adequate, new and powerful instrumentation. A large part of the nonthermal phenomena in the Universe can research are obvious. Special interest investigations as with existing low-fre missions (WIND, Cassini, etc.), and also ones (STEREO, SIRA, etc.). Finally, one must mention that even instrument on the ground will not help fo lower part of the electromagnetic spec radio frequency range below  10 MHz; w ARTICLE IN PRESS Fig. 11. Drifting ionosphere scintillation and wide-band IPS scintillation on Crab Nebula. A. Lecacheux et al. / Planetary and Space Science 52 (2004) 1357–1374 LSS science 

Calendar 2009 - 2012 : ANR funded prototype study 2011 : Feasibility validated 2011/09/12 : Equipex funding application 2012 : Operating prototype with 3 sub-arrays Station Lofar à Nançay - Comment? nique rojet en cours r un financement compatible avec l’ampleur du projet Demande portée par 3 laboratoires Responsables scientifiques: M.Tagger & P.Zarka Responsable technique: L.Denis e Une Super Station Lofar à Nançay - Comment? Une opportunité unique Qui s’articule avec le projet en cours Qui permet d’envisager un financement compatible avec l’ampleur du projet Demande portée par 3 laboratoires Responsables scientifiques: M.Tagger & P.Zarka Responsable technique: L.Denis Dosier EQUIPEX déposé le 12 septembre 

Tomorrow the LOFAR super station ?