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Radio Astronomy Activities at RRI

Radio Astronomy Activities at RRI. N. Udaya Shankar RRI. Indo-SA Astronomy Workshop 7 August 2012. The economically important Silk Road (red) and spice trade routes (blue). Pepper: MWA Precursor SKA EOI in SKA Low Science Case for SKA MID Evolution of HI in the universe. SALT.

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Radio Astronomy Activities at RRI

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  1. Radio Astronomy Activities at RRI N. Udaya Shankar RRI Indo-SA Astronomy Workshop 7 August 2012

  2. The economically important Silk Road (red) and spice trade routes (blue)

  3. Pepper: MWA Precursor SKA EOI in SKA Low Science Case for SKA MID Evolution of HI in the universe. SALT

  4. A&A group Theoretical astrophysics (5) Observational astronomy to (7) Builders: specialized instruments . • Collaborations: Many body interactions Lead to joint pursuit of problems in Theory, Observations, Specialized instruments • world-wide collaborations.

  5. Present Focus:Low Frequency Radio Astronomy.Frequencies Below: 1.4 GHz.Developing interest in the freq range: 2 to 4 GHz.

  6. Evolution of HI atom in the universe • a. HI mass fluctuations using ORT; • 327 MHz, z=3.3 • b. EoR : I. Statistical Detection • Our participation in MWA • 80-300 MHz, z=4-16 • ii. Global Signal Detection • In-house Projects • 87.5 – 175 MHz, z= 4-8 • c. ERA : Epoch of Recombination array • 2 – 4 GHz, z=1000 • 2.Transients and Pulsars, MWA and ORT

  7. 2.Transients and Pulsars, MWA and ORT 3. Halos and Relics in Galaxy Clusters GMRT and MWA 50 MHz system for GMRT 4. Multi-frequency observations of Compact objects , X-ray polarimeter.

  8. 2. Murchison Wide Field Array (MWA) MWA is a low-frequency imaging radio interferometer facility being built in the radio-quiet area of Western Australia

  9. This is one exciting project … • Scientifically rich • EOR, Solar, Transients, Pulsars, RRLs, etc. • Technologically innovative • Leading the way in multiple simultaneous areas • Trailblazing! • Excellent partnership • Common goals + motivations • Abundance of talent and energy • Enormous growth potential • Inexpensive hardware, Moore’s law • LFD/xNTD synergy, path to SKA • Opportunities abound, for Australian, Indian, US, and Global community MWA-LFD Kick-Off June 2006

  10. MWA Murchison

  11. Antenna tile with 16 dipoles placed on a ground screen of 5 x 5 m

  12. Cluster (50-100m diam.) Array (~1.5km diam.) Antenna tile (~4m diam.) tile node clusters Tile beamformer Fiber out Coax out Central Processing Physical Layout

  13. A digital receiver for MWA has been developed and built in the Radio Astronomy laboratory at RRI. • RRI digital receivers operate between 80 and 300 MHz and are based on state-of-the-art Virtex-5 FPGA chips • The receivers operate at 655 MHz sampling, include poly-phase digital filters and fiber optic links.

  14. MWA Digital Receiver Each receiver receives outputs from 8 tiles , digitize them, do 512 CH PFB and send them through fiber links after serializing.

  15. RRI contribution • Development of i) A/D and Filter Bank (ADFB) Architecture ii) Firmware for ADFB board • Development of i) Backplane and ii) Clock for 32 T digital receiver • Development of i) Hardware and firmware architecture for AGFO ii) Design of Board and firmware development • Development of Imaging Algorithms: Nithya’s Talk

  16. Current status • Actively involving in system testing under integrated environment • Planning to mass produce 16 digital receivers for 128 tiles by mid 2012 • Development of hardware and firmware to combine in the digital receiver the outputs of all 8 tiles to form one beam and use the entire bandwidth available

  17. Challenges for MWA, LOFAR, GMRT, Global Signal Detection Experiments are same

  18. Receiver is a 2 element interferometer with a space beam splitter • Freq. range : 87.5 – 175 MHz The screen is made resistive to ensure required phase diff. between transmitted and reflected signals exists and has equal transmission and reflected signals

  19. Receiver system for EoR detection • Frequency Independent Antennas installed over absorber tiles • Well matched receivers with low noise figure • a digital receiver consisting of a high speed digitizers and a spectro-correlator

  20. Current Status • The Zero space interferometer has been completely characterized for all its properties and data acquired are being analyzed. Next Phase: Take it to a radio quite zone Australia South Africa

  21. 5. X-Ray Polarimeter • X-ray polarimeter based on the principle of Thomson scattering is being developed at the Raman Research Institute (RRI) • The experiment has been proposed to the Indian Space Research Organization for a small satellite mission.

  22. Scientific Objective • Polarisation measurement gives insight about • The strength and the distribution of magnetic field in X-ray sources • Geometric anisotropies in the source • The nature of the accelerator responsible for energizing the electrons taking part in radiation and scattering. • The instrument is suitable for X-ray polarisation measurement of hard X-ray sources like • accretion powered pulsars, • black hole candidates in low-hard states etc.

  23. Instrument Specifications • Energy band covered – 5-30keV • Detectors – Proportional counters • Photon collection area ~ 1018 cm2 • Field of view - 33 degree with 0.5 degree flat response

  24. Current Status The development of a Thomson polarimeter including proportional counter detectors, associated front-end electronics, event processing logic, data acquisition system, and test and calibration system have been completed successfully. Engineering Model is being developed For more details contact : bpaul@rri.res.in

  25. Sub-mm telescope New Optics design has been developed for constructing large sub-millimeter radio telescope economically. Balasubramanyam, R, 2004, MNRAS, 354, 1189

  26. Current Status • At present a 3m Submillimeter-wave telescope prototype (3mSTeP) is being built • The mechanical structure, design and optimization are completed • Work on 8 GHz wide band spectrometer is under progress. • For more details: contact : ramesh@rri.res.in

  27. Possible Future Collaborations

  28. Studies of galaxy populations in merging galaxy clusters using SALT and GMRT. • Radio monitoring of transient X-ray sources, disk-jet connection. • 3. Optical reprocessing of X-rays, simultaneous observations with ASTROSAT and SALT. • 4. NIR-studies (in continuum and shocked molecular hydrogen @ 2.1/2.2 um) of chosen southern massive star forming regions. • 5. Observing for Global EoR signal detection in SKA site in SA.

  29. Gauribidanur T Array

  30. GBD_image

  31. MRT Aerial View

  32. Hierarchical Interference mitigation. • Imaging with a non-coplanar array. • Imaging two steradinas of the sky. • Human Resource Development: • 8 Ph.D. students • 1 MS student • Several student projects

  33. Major projects undertaken by RRI • Aperture Array for Low Frequency Radio astronomy • Development of Digital receivers for The Murchison Wide Field Array (MWA) • Multiband receiver system at Green Bank Telescope • Zero Spacing Interferometer to detect Cosmological Re-ionization Signatures • Development of an X-ray polarimeterfor small satellite mission • Upgradation of Ooty Radio Telescope • Development of a 3m Submillimeterwave telescope Prototype(3mSTeP)

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