Radio Astronomy Activities at RRI

N. Udaya ShankarRRI

Indo-SA Astronomy Workshop7 August 2012

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

SALT

Pepper:MWA Precursor SKAEOI in SKA LowScience Case for SKA MIDEvolution of HI in the universe.

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.

Present Focus:

Low Frequency Radio Astronomy.

Frequencies Below: 1.4 GHz.

Developing interest in the freq range: 2 to 4 GHz.

1.Evolution of HI atom in the universe

a. HI mass fluctuations using ORT; 327 MHz, z=3.3

b. EoR : I. Statistical DetectionOur participation in MWA80-300 MHz, z=4-16

ii. Global Signal DetectionIn-house Projects87.5 – 175 MHz, z= 4-887.5 – 175 MHz, z= 4-8

c. ERA : Epoch of Recombination array2 – 4 GHz, z=1000

2.Transients and Pulsars, MWA and ORT

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.

2. Murchison Wide Field Array 2. Murchison Wide Field Array (MWA(MWA))

MWA is a low-frequency imaging radio MWA is a low-frequency imaging radio interferometer facility being built in the interferometer facility being built in the radio-quiet area of Western Australiaradio-quiet area of Western Australia

MWA-LFD Kick-Off June 2006

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

Murchison

MWA

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

Physical Layout

Antenna tile (~4m diam.)

clusters

Array (~1.5km diam.)

tile

Cluster (50-100m diam.)

node

Coax out

Tile beamformerFiber out

Central Processing

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.

MWA Digital Receiver

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

RRI contributionDevelopment 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

Current statusActively 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

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

Receiver is a 2 element interferometer with a space beam splitter

Freq. range : 87.5 – 175 MHzFreq. range : 87.5 – 175 MHzThe screen is made resistive to ensure required phase diff. between transmitted and reflected signals exists and has equal transmission and reflected signals

Receiver system for EoR detection

i) Frequency Independent Antennas installed over absorber tiles

ii) Well matched receivers with low noise figure

iii)a digital receiver consisting of a high speed digitizers and a spectro-correlator

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

5. X-Ray PolarimeterX-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.

Scientific ObjectivePolarisation 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.

Instrument Specifications

Energy band covered – 5-30keV

Detectors – Proportional counters

Photon collection area ~ 1018 cm2

Field of view - 33 degree with 0.5 degree flat response

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

Sub-mm telescope

New Optics design has been developed for constructing large sub-millimeter radio telescope economically.

Balasubramanyam, R, 2004, MNRAS, 354, 1189

Current StatusAt 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

Possible Future Collaborations

1.Studies of galaxy populations in merging galaxy clusters using SALT and GMRT.

2.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.

Gauribidanur T Array

GBD_image

MRT Aerial View

1.Hierarchical Interference mitigation.2.Imaging with a non-coplanar array.3.Imaging two steradinas of the sky.

4.Human Resource Development:

8 Ph.D. students1 MS studentSeveral student projects

Major projects undertaken by RRI

1. Aperture Array for Low Frequency Radio astronomy

2. Development of Digital receivers for The Murchison Wide Field The Murchison Wide Field Array (MWA)Array (MWA)

3.3. Multiband receiver system at Green Bank TelescopeMultiband receiver system at Green Bank Telescope

4. Zero Spacing Interferometer to detect Cosmological Re-ionization Signatures

5. Development of an X-ray polarimeter for small satellite mission

6. Upgradation of Ooty Radio Telescope

7. Development of a 3m Submillimeterwave telescope Prototype(3mSTeP)