Experiment to Detect the Global EoR Signature
|Part of||Murchison Radio-astronomy Observatory|
|Telescope style||Radio telescope|
The Experiment to Detect the Global EoR Signature (EDGES) is an experiment and radio telescope located in a radio quiet zone at the Murchison Radio-astronomy Observatory in Western Australia. It is a collaboration between Arizona State University and Haystack Observatory, with infrastructure provided by CSIRO. EoR stands for epoch of reionization, a time in cosmic history when neutral atomic hydrogen gas became ionised due to ultraviolet light from the first stars.
The experiment has two low-band instruments, each of which has a dipole antenna pointed to the zenith and observing a single polarisation. The antenna is around 2 by 1 metre (6.6 ft × 3.3 ft) in size, sat on a 30 by 30 metres (98 ft × 98 ft) ground shield. It is coupled with a radio receiver, with a 100m cable run to a digital spectrometer. The instruments operate at 50–100 MHz (6.0–3.0 m), and are separated by 150m. Observations started in August 2015.
78 MHz absorption profile
In March 2018 the collaboration published a paper in Nature announcing the discovery of a broad absorption profile centered at a frequency of MHz in the sky-averaged signal after subtracting Galactic synchrotron emission. The absorption profile has a width of MHz and an amplitude of K, against a background RMS of 0.025K, giving it a signal-to-noise ratio of 37. The equivalent redshift is centered at , spanning z=20–15. The signal is possibly due to ultraviolet light from the first stars in the Universe altering the emission of the 21cm line. A "more exotic scenario" is that the signal is due to interactions between dark matter and baryons.
The high-band instrument is of similar design, and operates at 90–200 MHz (3.3–1.5 m).
- "MIT Haystack Observatory: EDGES". www.haystack.mit.edu. Retrieved 2 March 2018.
- Bowman, Judd D.; Rogers, Alan E. E.; Monsalve, Raul A.; Mozdzen, Thomas J.; Mahesh, Nivedita (1 March 2018). "An absorption profile centred at 78 megahertz in the sky-averaged spectrum". Nature. 555 (7694): 67–70. arXiv:1810.05912. Bibcode:2018Natur.555...67B. doi:10.1038/nature25792. ISSN 1476-4687. PMID 29493587.
- Barkana, Rennan (1 March 2018). "Possible interaction between baryons and dark-matter particles revealed by the first stars". Nature. 555 (7694): 71–74. arXiv:1803.06698. Bibcode:2018Natur.555...71B. doi:10.1038/nature25791. ISSN 1476-4687. PMID 29493590.