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Progress of modern low frequency instruments towards a successful EoR HI detection

Event Details

Event Dates: 

Friday, January 27, 2017 - 12:00pm

Seminar Location: 

  • JILA 10th Floor - Foothills Room

Speaker Name(s): 

Nithyanandan Thyagarajan

Speaker Affiliation(s): 

Arizona State University
Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysics Lunch Seminar

Event Details & Abstract: 

The epoch of reionization marked an important phase transition in the Universe's evolution with the emergence of the first stars and galaxies. Detecting this epoch will fill a major gap in understanding the history of the Universe. A direct and very promising probe of this epoch is through detection of neutral Hydrogen in the IGM through redshifted 21cm emission. Many ongoing experiments designed for this direct detection, including the Murchison Widefield Array (MWA), the Low Frequency Array (LOFAR), and the Precision Array for Probing the Epoch of Reionization (PAPER), have now obtained thousands of hours of data, theoretically sufficient for a high significance detection. And yet, the detection of EoR has remained elusive. It is emerging that systematic limitations caused by the bright foregrounds and the instrumental transfer functions are the primary reasons preventing EoR detection. These include bright synchrotron spectra, instrument's wide-field response, chromatic antenna beam response, geometrical and electrical reflections in the structural and analog assemblies besides numerous other reasons. I will discuss the impact of these effects on the measured power spectrum, namely, the introduction of unsmooth spectral structures that mimic and contaminate the cosmological signal which results in a degradation in sensitivity. I will summarize results from current experiments and describe how new instruments such as the Hydrogen Epoch of Reionization Array (HERA) are addressing these concerns in their design in pursuit of a successful EoR detection.