EDGES
21-cm System Meeting Agenda
EDGES: Experiment to Detect the Global EoR Signature
See also the MIT EDGES memo series and the ASU EDGES memo series.
EDGES is a collaboration between Arizona State University and MIT Haystack Observatory, funded by the National Science Foundation (NSF). It is located at the Murchison Radio-astronomy Observatory (MRO) in a radio-quiet zone in western Australia, with onsite infrastructure support provided by Australia’s CSIRO.
The latest EDGES research is available from Nature, An absorption profile centred at 78 megahertz in the sky-averaged spectrum.
The MIT News article on EDGES is available at http://news.mit.edu/2018/astronomers-detect-earliest-evidence-yet-hydrogen-universe-0228.
The NSF has created an excellent video explanation of the EDGES signal detection:
The project’s goal is radio detection of hydrogen signatures from the historical period in the formation of the universe known as the Epoch of Reionization (EoR), soon after the formation of the first stars and galaxies.
An excellent detailed explanation of the cosmological mysteries being investigated by EDGES scientists is available from ASU.
Technology
EDGES is a small, ground-based antenna system including a low-band and a high-band instrument, a receiver, a spectrometer, and a ground plane, as well as associated electronics and other components.
The equipment consists of a broadband antenna, about 2 meters long and 1 meter high, covering a range of 50–100 MHz; a metal ground plane, 30 x 30 m; and a receiver under the ground plane connected via underground cables to a digital radio spectrometer in an electronics hut situated at a distance of 100 meters. The instrument is located away in the radio-quiet zone of the Murchison Radio-astronomy Observatory in Western Australia. The electronics has both built-in calibration that operates in the field, as well as accurate calibration of the low noise amplifier and the internal antenna reflection measurement system standards made in the laboratory.
The antennas and portions of the receiver were designed and constructed by MIT Haystack Observatory’s Dr. Alan Rogers and the Haystack team; Judd Bowman, Raul Monsalve, and the ASU team added an automated antenna reflection measurement system to the receiver, outfitted the control hut with the electronics, constructed the ground plane, and conducted the field work for the project. Australia’s Commonwealth Scientific and Industrial Research Organization provides on-site infrastructure for the EDGES project.
Publications
- Bowman, Judd D., Alan EE Rogers, Raul A. Monsalve, Thomas J. Mozdzen, and Nivedita Mahesh. "Reply to Hills et al." Nature 564 (2018): E35-E35.
- Monsalve, R.A., A. Fialkov, J.D. Bowman, A.E.E. Rogers, T.J. Mozdzen, A. Cohen, R. Barkana, N. Mahesh, (2019), Results from EDGES High-Band. III. New Constraints on Parameters of the Early Universe, ApJ, 875, 67, doi.org/10.3847/1538-4357/ab07be.
- Mozdzen, T.J., N Mahesh R A Monsalve A E E Rogers J D Bowman, Spectral Index of the Diffuse Radio Background Between 50 and 100 MHz Monthly Notices of the Royal Astronomical Society, sty3410, Published:17 December 2018. doi.org/10.1093/mnras/sty3410
- Monsalve, R.A., Bradley Greig, Judd D. Bowman, Andrei Mesinger, Alan E.E. Rogers and Thomas J. Mozdzen, Nicholas S. Kern and Nivedita Mahesh, Results from EDGES High-band. II. Constraints on Parameters of Early Galaxies, The Astrophysical Journal 863, No 1 (2018): doi:10.3847/1538-4357/aace54
- Monsalve, Raul A., Alan EE Rogers, Judd D. Bowman, and Thomas J. Mozdzen (2017), Results from EDGES High-band. I. Constraints on Phenomenological Models for the Global 21 cm Signal. The Astrophysical Journal 847, no. 1 (2017): 64. doi:10.3847/1538-4357/aa88d1
- Bowman, Judd D., Rogers, Alan E.E., Monsalve, Raul A., Mozdzen, Thomas J., and Mahesh Nivedita. (2018). An absorption profile centred at 78 megahertz in the sky-averaged spectrum. Nature 555, 67–70. doi:10.1038/nature25792
- Monsalve, R.A., Rogers, A.E.E., Bowman, J.D., and Mozden, T.J. (2017). Calibration of the EDGES high-band receiver to observe the global 21 cm from the Epoch of Reionization. Astrophysical Journal 835(1). doi:10.3847/1538-4357/835/1/49
- Monsalve, R.A., Rogers, A.E.E., Mozdzen, T.J., and Bowman, J.D. (2016). One-port direct/reverse method for characterizing VNA calibration standards. IEEE Transactions on Microwave Theory and Techniques 64(8): 2631–2639. (PDF)
- Mozdzen, Thomas J., Judd D. Bowman, Raul A. Monsalve, and Alan EE Rogers (2016). "Improved measurement of the spectral index of the diffuse radio background between 90 and 190 MHz." Monthly Notices of the Royal Astronomical Society 464(4): 4995-5002. doi: 10.1093/mnras/stw2696
- Rogers, A. E. E., Bowman, J. D., Vierinen, J., Monsalve, R. and Mozdzen, T. (2015). Radiometric measurements of electron temperature and opacity of ionospheric perturbations. Radio Sci., 50, 130–137. doi: 10.1002/2014RS005599
- Mozdzen, T. J., Bowman, J.D., Monsalve, R.A., Rogers, A.E.E. (2015). Limits on foreground subtraction from chromatic beam effects in global redshifted 21 cm measurements. Monthly Notices of the Royal Astronomical Society 2015 455(4): 3890–3900. doi: 10.1093/mnras/stv2601
- Rogers, A.E.E., Bowman, J.D. (2012). Absolute calibration of a wideband antenna and spectrometer for accurate sky noise temperature measurements. Radio Science 47, RS0K06, doi: 10.1029/2011RS004962 (PDF)
- Bowman, J.D., Rogers, A.E.E. (2010). A lower limit of Δz > 0.06 for the duration of the reionization epoch. Nature 468, pp. 796-797.
- Rogers, A.E.E., Bowman, J.D. (2008). Spectral Index of the Diffuse Radio Background Measured from 100 to 200 MHz. AJ 136(2), pp. 641-648.
- Bowman, J.D., Rogers, A.E.E. Hewitt, J.N. (2008). Toward empirical constraints on the global redshifted 21 cm brightness temperature during the Epoch of Reionization. Ap.J. 676(1), 1–9.
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