First Season Mwa Eor Power Spectrum Results at Redshift 7

Beardsley, Adam P.; Hazelton, B. J.; Sullivan, M.; Carroll, P.; Barry, N.; Rahimi, M.; Pindor, B.; Trott, Cathryn M.; Line, J.; Jacobs, Daniel; Morales, M. F.; Pober, Jonathan C.; Bernardi, G.; Bowman, Judd D.; Busch, Michael P.; Briggs, F.; Cappallo, R. J.; Corey, B. E.; Oliveira-Costa, A. de; Dillon, Joshua S.; Emrich, D.; Ewall‐Wice, Aaron; Lü, Feng; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hewitt, Jacqueline N.; Hurley‐Walker, N.; Johnston‐Hollitt, M.; Kaplan, David L.; Kasper, J. C.; Kim, Han-Seek; Kratzenberg, E.; Lenc, E.; Loeb, Abraham; Lonsdale, Colin J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morgan, E.; Neben, Abraham R.; Thyagarajan, Nithyanandan; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, S.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Shankar, N. Udaya; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, Max; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, Chen; Wyithe, J. Stuart B.

doi:10.3847/1538-4357/833/1/102

Cited by 187 publications

(212 citation statements)

References 99 publications

(166 reference statements)

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“…Although a direct detection of the 21-cm signal continues to be elusive, the PAPER radio interferometer derived lower limits in the range 5-10 K on the IGM temperature at z = 8.4 based on upper limits to the power spectrum of 21-cm spatial fluctuations at that epoch; the derived limit depends on the assumed ionization fraction (Pober et al 2015). Recently, additional upper limits on the 21-cm power spectrum have been reported by MWA (Beardsley et al 2016) and LOFAR (Patil et al 2017). …”

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confidence: 99%

First Results on the Epoch of Reionization from First Light with SARAS 2

Singh

Subrahmanyan

Shankar

et al. 2017

ApJL

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138

115

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Long wavelength spectral distortions in the Cosmic Microwave Background arising from the 21-cm transition in neutral Hydrogen are a key probe of Cosmic Dawn and the Epoch of Reionization. These features may reveal the nature of the first stars and ultra-faint galaxies that transformed the spin temperature and ionization state of the primordial gas. SARAS 2 is a spectral radiometer purposely designed for precision measurement of these monopole or all-sky global 21-cm spectral distortions. We use 63 hr night time observing of the radio background in the frequency band 110-200 MHz with the radiometer deployed at the Timbaktu Collective in Southern India to derive likelihoods for plausible redshifted 21-cm signals predicted by theoretical models. First light with SARAS 2 disfavors the class of models that feature weak X-ray heating (with f X ≤ 0.1) and rapid reionization (with peak dT b dz ≥ 120 mK per unit redshift interval ).

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confidence: 99%

First Results on the Epoch of Reionization from First Light with SARAS 2

Singh

Subrahmanyan

Shankar

et al. 2017

ApJL

Self Cite

138

115

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“…Source subtraction (Ali, Bharadwaj & Chengalur 2008;Ghosh et al 2012;Beardsley et al 2016;Gehlot et al 2018;Kerrigan et al 2018) offers a technique for foreground mitigation; this, however, is limited by our ability to accurately calibrate the visibility data and model the sources. The TGSS ADR1 uses a novel method to incorporate Directiondependent (DD) calibration to all the data sets.…”

Section: Introductionmentioning

confidence: 99%

All-sky angular power spectrum – I. Estimating brightness temperature fluctuations using the 150-MHz TGSS survey

Choudhuri

Ghosh

Roy

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Measurements of the Galactic synchrotron emission is relevant for the 21-cm studies from the Epoch of Reionization. The study of the synchrotron emission is also useful to quantify the fluctuations in the magnetic field and the cosmic ray electron density of the turbulent interstellar medium (ISM) of our Galaxy. Here, we present the all-sky angular power spectrum (C ) measurements of the diffuse synchrotron emission using the TIFR GMRT Sky Survey (TGSS) at 150 MHz. We estimate C using visibility data both before and after subtracting the modelled point sources. The amplitude of the measured C falls significantly after subtracting the point sources, and it is also slightly higher in the Galactic plane for the residual data. The residual C is most likely to be dominated by the Galactic synchrotron emission. The amplitude of the residual C falls significantly away from the Galactic plane. We find the measurements are quite symmetric in the Northern and Southern hemispheres except in the latitude range 15 − 30 • which is the transition region from the disk dominated to diffuse halo dominated region. The comparison between this interferometric measurement with the scaled version of the Haslam rms map at 150 MHz shows that the correlation coefficient (r) is more than 0.5 for most of the latitude ranges considered here. This signifies the TGSS survey is quite sensitive to the diffuse Galactic synchrotron radiation.

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“…These observational efforts have resulted in upper limits of the 21cm power spectrum and on the ionized state of the IGM at z ∼ 8 (e.g. Parsons et al 2014;Ali et al 2015;Pober et al 2015 ;Greig et al 2016;Beardsley et al 2016). Furthermore, future instruments such as the Square Kilometre Array (SKA) (Mellema et al 2013) and Hydrogen Epoch of Reionization Array (HERA) (DeBoer et al 2016) are designed to detect the 21cm signal power spectrum with higher signal to noise ratio and at higher redshift, during the Cosmic Dawn.…”

Section: Introductionmentioning

confidence: 99%

Analysing the 21 cm signal from the epoch of reionization with artificial neural networks

Shimabukuro¹,

Semelin²

2017

Monthly Notices of the Royal Astronomical Society

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The 21 cm signal from the Epoch of Reionization should be observed within the next decade. While a simple statistical detection is expected with SKA pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract from the observed data constraints on the parameters describing the underlying astrophysical processes, inversion methods must be developed. For example, the Markov Chain Monte Carlo method has been successfully applied. Here we test another possible inversion method: artificial neural networks (ANN). We produce a training set which consists of 70 individual sample. Each sample is made of the 21 cm power spectrum at different redshifts produced with the 21cmFast code plus the value of three parameters used in the semi-numerical simulations that describe astrophysical processes. Using this set we train the network to minimize the error between the parameter values it produces as an output and the true values. We explore the impact of the architecture of the network on the quality of the training. Then we test the trained network on the new set of 54 test samples with different values of the parameters. We find that the quality of the parameter reconstruction depends on the sensitivity of the power spectrum to the different parameters at a given redshift, that including thermal noise and sample variance decreases the quality of the reconstruction and that using the power spectrum at several redshifts as an input to the ANN improves the quality of the reconstruction. We conclude that ANNs are a viable inversion method whose main strength is that they require a sparse exploration of the parameter space and thus should be usable with full numerical simulations.

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First Season Mwa Eor Power Spectrum Results at Redshift 7

Cited by 187 publications

References 99 publications

First Results on the Epoch of Reionization from First Light with SARAS 2

First Results on the Epoch of Reionization from First Light with SARAS 2

All-sky angular power spectrum – I. Estimating brightness temperature fluctuations using the 150-MHz TGSS survey

Analysing the 21 cm signal from the epoch of reionization with artificial neural networks

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