Preparing for the Dark Ages Radio Explorer through Ground-Based Observations talk

July 19, 2017 - Raul Monsalve

Download talk (PDF file) (5.1MB) or watch the video.

Abstract: The Dark Ages Radio Explorer (DARE) is a mission concept proposed to the NASA MIDEX program to measure the global redshifted 21-cm signal from orbit above the far side of the Moon. This cosmological signal was emitted by neutral hydrogen before the first billion years of the universe (redshifts > 6) when the first stars, black holes, and galaxies formed, altering the temperature and ionization state of the intergalactic medium on large scales. Due to cosmological expansion, the frequency of the signal has decreased from 1420 MHz (rest frame) to the range 40-200 MHz. A precision measurement of the 21-cm signal spectrum in this frequency range would provide critical information about the first compact objects and their impact on their environments and the evolution of the universe. DARE is a collaboration between top universities, research centers, including NASA Ames, and aerospace industry partners. It is led by the University of Colorado Boulder. In this talk I will describe the efforts of a ground-based pathfinder for DARE. It is called Experiment to Detect the Global EoR Signature (EDGES) and observes the sky below 200 MHz from the desert in Western Australia. Specifically, EDGES operates two independent single-antenna total power spectrometers: EDGES High-Band (90-200 MHz) and EDGES Low-Band (50-100 MHz). EDGES has produced the only constraints on the Epoch of Reionization (EoR) (13 > z > 6) to date using this type of measurements, and with its current observations it intends to provide significant constraints on the features of the 21-cm signal at higher redshifts. In my talk I will describe the EDGES instruments, the calibration of the observations, and the results obtained from data collected since 2015, after the latest major instrumental upgrade. This will be presented in the context of its application for observations from space with DARE.