Closing in on 12-billion-year-old signal:

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Jun 12, 2020.

  1. paddoboy Valued Senior Member


    Scientists close in on 12-billion-year-old signal from the end of the universe's 'dark age'

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    Part of the Murchison Widefield Array at night. Credit: John Goldfield/Celestial Visions

    Today, stars fill the night sky. But when the universe was in its infancy, it contained no stars at all. And an international team of scientists is closer than ever to detecting, measuring and studying a signal from this era that has been traveling through the cosmos ever since that starless era ended some 13 billion years ago.

    That team—led by researchers at the University of Washington, the University of Melbourne, Curtin University and Brown University—reported last year in the Astrophysical Journal that it had achieved an almost 10-fold improvement of radio emission data collected by the Murchison Widefield Array. Team members are currently scouring the data from this radio telescope in remote Western Australia for a telltale signal from this poorly understood "dark age" of our universe.

    Learning about this period will help address major questions about the universe today.

    "We think the properties of the universe during this era had a major effect on the formation of the first stars and set in motion the structural features of the universe today," said team member Miguel Morales, a UW professor of physics. "The way matter was distributed in the universe during that era likely shaped how galaxies and galactic clusters are distributed today."
    more at link....................
    "For this dark age, of course there's no light-based signal we can study to learn about it—there was no visible light!" said Morales. "But there is a specific signal we can look for. It comes from all that neutral hydrogen. We've never measured this signal, but we know it's out there. And it's difficult to detect because in the 13 billion years since that signal was emanated, our universe has become a very busy place, filled with other activity from stars, galaxies and even our technology that drown out the signal from the neutral hydrogen."

    the paper:

    First Season MWA Phase II Epoch of Reionization Power Spectrum Results at Redshift 7:


    The compact configuration of Phase II of the Murchison Widefield Array (MWA) consists of both a redundant subarray and pseudo-random baselines, offering unique opportunities to perform sky-model and redundant interferometric calibration. The highly redundant hexagonal cores give improved power spectrum sensitivity. In this paper, we present the analysis of nearly 40 hr of data targeting one of the MWA's epoch of reionization (EoR) fields observed in 2016. We use both improved analysis techniques presented in Barry et al. and several additional techniques developed for this work, including data quality control methods and interferometric calibration approaches. We show the EoR power spectrum limits at redshift 6.5, 6.8, and 7.1 based on our deep analysis on this 40 hr data set. These limits span a range in k-space of 0.18 h Mpc−1 < k < 1.6 h Mpc−1, with a lowest measurement of Δ2 ≤ 2.39 × 103 mK2 at k = 0.59 h Mpc−1 and z = 6.5.

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    Kangaroos at the Murchison Widefield Array. Credit: MWA Collaboration/Curtin University

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