A 21-cm power spectrum at 48 MHz, using the Owens Valley Long Wavelength Array. (arXiv:2102.09596v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Garsden_H/0/1/0/all/0/1">Hugh Garsden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Greenhill_L/0/1/0/all/0/1">Lincoln Greenhill</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bernardi_G/0/1/0/all/0/1">Gianni Bernardi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fialkov_A/0/1/0/all/0/1">Anastasia Fialkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Price_D/0/1/0/all/0/1">Daniel C. Price</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mitchell_D/0/1/0/all/0/1">Daniel Mitchell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dowell_J/0/1/0/all/0/1">Jayce Dowell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spinelli_M/0/1/0/all/0/1">Marta Spinelli</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schinzel_F/0/1/0/all/0/1">Frank K. Schinzel</a>
The Large-aperture Experiment to Detect the Dark Age (LEDA) was designed to
measure brightness temperature fluctuations in the Cosmic Microwave Background
due to 21-cm absorption/emission by neutral hydrogen in the early Universe.
Measurements of 21-cm fluctuations will provide constraints on astrophysical
processes during Cosmic Dawn ($z approx 15-30$). LEDA uses observations made
with the Owens Valley Long Wavelength Array (OVRO-LWA) in California, a compact
imaging interferometer. We present a power spectrum of observations at 48 MHz
($z approx 28$), and an analysis of the sensitivity of the OVRO-LWA telescope.
Recently, Eastwood et al. published a power spectrum of OVRO-LWA observations
generated from m-mode analysis, using statistical techniques to remove
foregrounds. We use a method that isolates foreground power in a “wedge” in the
power spectrum; outside of the wedge, in the “Cosmic Dawn” window, 21-cm
fluctuations may be detected. Using 4 hrs of incoherently integrated OVRO-LWA
observations, we measure a power of $Delta^2(k) approx 2 times 10^{12}$
mK$^2$ in the Cosmic Dawn window. Given that a value of $Delta^2(k) approx
100$ mK$^2$ is predicted from theory, we conclude that our power spectrum is
dominated by telescope thermal noise and systematic effects. By modelling the
OVRO-LWA thermal noise, we show that OVRO-LWA has sufficient sensitivity for a
21-cm detection if 3000 hrs of observations are integrated using a mix of
incoherent and coherent averaging. We show that OVRO-LWA will then be able to
detect theoretically predicted Ly-$alpha$ and X-ray peaks in 21-cm power
spectra at Cosmic Dawn, according to theoretical models.
The Large-aperture Experiment to Detect the Dark Age (LEDA) was designed to
measure brightness temperature fluctuations in the Cosmic Microwave Background
due to 21-cm absorption/emission by neutral hydrogen in the early Universe.
Measurements of 21-cm fluctuations will provide constraints on astrophysical
processes during Cosmic Dawn ($z approx 15-30$). LEDA uses observations made
with the Owens Valley Long Wavelength Array (OVRO-LWA) in California, a compact
imaging interferometer. We present a power spectrum of observations at 48 MHz
($z approx 28$), and an analysis of the sensitivity of the OVRO-LWA telescope.
Recently, Eastwood et al. published a power spectrum of OVRO-LWA observations
generated from m-mode analysis, using statistical techniques to remove
foregrounds. We use a method that isolates foreground power in a “wedge” in the
power spectrum; outside of the wedge, in the “Cosmic Dawn” window, 21-cm
fluctuations may be detected. Using 4 hrs of incoherently integrated OVRO-LWA
observations, we measure a power of $Delta^2(k) approx 2 times 10^{12}$
mK$^2$ in the Cosmic Dawn window. Given that a value of $Delta^2(k) approx
100$ mK$^2$ is predicted from theory, we conclude that our power spectrum is
dominated by telescope thermal noise and systematic effects. By modelling the
OVRO-LWA thermal noise, we show that OVRO-LWA has sufficient sensitivity for a
21-cm detection if 3000 hrs of observations are integrated using a mix of
incoherent and coherent averaging. We show that OVRO-LWA will then be able to
detect theoretically predicted Ly-$alpha$ and X-ray peaks in 21-cm power
spectra at Cosmic Dawn, according to theoretical models.
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