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  1. No Access

    Article

    Detecting global signal from cosmic dawn and epoch of reionization with SKA

    A key science project for SKA-Low is the interferometer imaging of spatio-temporal fluctuations in the hydrogen ionization fraction and spin temperature as a diagnostic of cosmic dawn (CD) and epoch of reioniz...

    Mayuri Sathyanarayana Rao, N. Udaya Shankar in Journal of Astrophysics and Astronomy (2023)

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    Article

    On the detection of a cosmic dawn signal in the radio background

    The astrophysics of the cosmic dawn, when star formation commenced in the first collapsed objects, is predicted to be revealed by spectral and spatial signatures in the cosmic radio background at long waveleng...

    Saurabh Singh, Jishnu Nambissan T., Ravi Subrahmanyan, N. Udaya Shankar in Nature Astronomy (2022)

  3. Article

    Open Access

    Peering into the dark (ages) with low-frequency space interferometers

    The Dark Ages and Cosmic Dawn are largely unexplored windows on the infant Universe (z ~ 200–10). Observations of the redshifted 21-cm line of neutral hydrogen can provide valuable new insight into fundamental...

    Léon V. E. Koopmans, Rennan Barkana, Mark Bentum, Gianni Bernardi in Experimental Astronomy (2021)

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    Article

    SARAS 3 CD/EoR radiometer: design and performance of the receiver

    SARAS is an ongoing experiment aiming to detect the redshifted global 21-cm signal expected from Cosmic Dawn (CD) and the Epoch of Reionization (EoR). Standard cosmological models predict the signal to be pres...

    Jishnu Nambissan T., Ravi Subrahmanyan, R. Somashekar in Experimental Astronomy (2021)

  5. No Access

    Article

    SARAS 2: a spectral radiometer for probing cosmic dawn and the epoch of reionization through detection of the global 21-cm signal

    The global 21-cm signal from Cosmic Dawn (CD) and the Epoch of Reionization (EoR), at redshifts ...

    Saurabh Singh, Ravi Subrahmanyan, N. Udaya Shankar in Experimental Astronomy (2018)

  6. Article

    Open Access

    Relativistic inverse Compton scattering of photons from the early universe

    Electrons at relativistic speeds, diffusing in magnetic fields, cause copious emission at radio frequencies in both clusters of galaxies and radio galaxies through non-thermal radiation emission called synchro...

    Siddharth Malu, Abhirup Datta, Sergio Colafrancesco in Scientific Reports (2017)

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    Article

    A digital-receiver for the MurchisonWidefield Array

    An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in W...

    Thiagaraj Prabu, K. S. Srivani, D. Anish Roshi, P. A. Kamini in Experimental Astronomy (2015)

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    Article

    SARAS: a precision system for measurement of the cosmic radio background and signatures from the epoch of reionization

    SARAS is a correlation spectrometer purpose designed for precision measurements of the cosmic radio background and faint features in the sky spectrum at long wavelengths that arise from redshifted 21-cm from g...

    Nipanjana Patra, Ravi Subrahmanyan, A. Raghunathan in Experimental Astronomy (2013)

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    Article

    18 GHz SZ Measurements of the Bullet Cluster

    We present 18 GHz observations of the Bullet cluster using the Austalia Telescope Compact Array (ATCA), which show structure in the Sunyaev–Zeldovich effect; in particular, a deep, compact feature which does n...

    Siddharth S. Malu, Ravi Subrahmanyan in Journal of Astrophysics and Astronomy (2011)

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    Article

    The Australia telescope 20 GHz survey: hardware, observing strategy, and scanning survey catalog

    The Australia Telescope 20 GHz (AT20G) survey is a large area (2π sr), sensitive (40 mJy), high frequency (20 GHz) survey of the southern sky. The survey was conducted in two parts: an initial fast scanning surve...

    Paul Jacob Hancock, Paul Roberts, Michael J. Kesteven in Experimental Astronomy (2011)

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    Chapter and Conference Paper

    Radio Monitoring of Supernova 2001ig: The First Year

    Supernova 2001ig in NGC 7424 has been observed with the Australia Telescope Compact Array at ∼2 week intervals since its discovery, making this the best-studied Type IIb radio supernova since SN 1993J.We prese...

    Stuart D. Ryder, Elaine Sadler, Ravi Subrahmanyan, Kurt W. Weiler in Cosmic Explosions (2005)

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    Article

    A measurement of the cosmic microwave background temperature 1280 MHz

    The absolute temperature of the cosmic microwave background (CMB) has been measured at a frequency of 1280 MHz. The observation was made with a modified version of the L-band receiver used in the Giant Metre w...

    A. Raghunathan, Ravi Subrahmanyan in Journal of Astrophysics and Astronomy (2000)

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    Article

    Microwave background radiation related evidence in favour of the standard model

    The discovery of the 3K microwave background radiation (MBR) and its interpretation as a relict of the hot big bang was probably the most important observation that led to the elevation of the hot big bang model ...

    Ravi Subrahmanyan in Journal of Astrophysics and Astronomy (1997)

  14. No Access

    Article

    Combined Simulation and Measurement Study of Temperature Uniformity in Rapid Thermal Processing

    Modeling and simulation of rapid thermal processing has been studied extensively in the past. This work presents the results of a combined simulation and measurement study of a commercial multilamp RTP chamber...

    Yur-Tsai Lin, Ravi Subrahmanyan, A. R. Sitaram in MRS Online Proceedings Library (1993)

  15. No Access

    Article

    Mechanical and Accelerated Testing of Flip Chip Interconnect Systems

    Flip chip interconnect systems are becoming increasingly popular in the electronics industry due to their low profile and high densities. During temperature cycles, the differential expansions between various ...

    Ravi Subrahmanyan in MRS Online Proceedings Library (1993)

  16. No Access

    Chapter

    Nonlinear Analysis of a Ceramic Pin Grid Array (PGA) Soldered to an Orthotropic Epoxy Substrate

    The pin grid array (PGA) is one form of first-level package.1–4 It has had a predominant role in high-density packaging for many years and is commonly used in high-performance computers. The advantages of the PGA...

    John Lau, Ravi Subrahmanyan, Steve Erasmus in Thermal Stress and Strain in Microelectron… (1993)

  17. Article

    An observational constraint on the existence of proto-superclsuters atz=3.3

    Ravi Subrahmanyan, G. Swarup in Journal of Astrophysics and Astronomy (1990)

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    Article

    An observational constraint on the existence of proto-superclusters at z =3.3

    Observations have been conducted using the Ooty Radio Telescope in order to place constraints on the evolutionary scenario leading to the formation of the present day superclusters. The experiment attempted to...

    Ravi Subrahmanyan, G. Swarup in Journal of Astrophysics and Astronomy (1990)

  19. No Access

    Article

    A search for protocliisters atz = 3.3

    We have used the Very Large Array to image a single field in a set of adjacent frequency bands around 333.0 MHz in an attempt to detect 21 cm emission from large scale H I inhomogeneities at a redshift of z = ...

    Ravi Subrahmanyan, K. R. Anantharamaiah in Journal of Astrophysics and Astronomy (1990)

  20. No Access

    Article

    The alignment of distant radio sources

    The relative orientation of the axes of extragalactic extended radio sources was first investigated by Willson1, who noted that in the 3CR sample there was a tendency for the axes to lie parallel to each other fo...

    Vijay K. Kapahi, Ravi Subrahmanyan, Ashok K. Singal in Nature (1985)