Science with the Murchison Widefield Array

Bowman, Judd D.; Cairns, Iver; Kaplan, David L.; Murphy, Tara; Oberoi, Divya; Staveley-Smith, Lister; Arcus, Wayne; Barnes, David G.; Bernardi, Gianni; Briggs, Frank H.; Brown, Shea; Bunton, John D.; Burgasser, Adam J.; Cappallo, Roger J.; Chatterjee, Shami; Corey, Brian E.; Coster, Anthea; Deshpande, Avinash; deSouza, Ludi; Emrich, David; Erickson, Philip; Goeke, Robert F.; Gaensler, B. M.; Greenhill, Lincoln J.; Harvey-Smith, Lisa; Hazelton, Bryna J.; Herne, David; Hewitt, Jacqueline N.; Johnston-Hollitt, Melanie; Kasper, Justin C.; Kincaid, Barton B.; Koenig, Ronald; Kratzenberg, Eric; Lonsdale, Colin J.; Lynch, Mervyn J.; Matthews, Lynn D.; McWhirter, S. Russell; Mitchell, Daniel A.; Morales, Miguel F.; Morgan, Edward H.; Ord, Stephen M.; Pathikulangara, Joseph; Thiagaraj, Prabu; Remillard, Ronald A.; Robishaw, Timothy; Rogers, Alan E. E.; Roshi, Anish A.; Salah, Joseph E.; Sault, Robert J.; Shankar, N. Udaya; Srivani, K. S.; Stevens, Jamie B.; Subrahmanyan, Ravi; Tingay, Steven J.; Wayth, Randall B.; Waterson, Mark; Webster, Rachel L.; Whitney, Alan R.; Williams, Andrew J.; Williams, Christopher L.; Wyithe, J. Stuart B.

doi:10.48550/arxiv.1212.5151

Cited by 3 publications

(3 citation statements)

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“…Several experiments have started observing the EoR, among them the MWA 5 , and PAPER 6 , which have obtained upper limits on the 21-cm power spectrum at z ∼ 7 [105][106][107][108]. Nonetheless, this effort will yield accurate measurements of the neutral-hydrogen distribution during the EoR, especially as HERA 7 is built and starts taking data [109].…”

Section: -Cmmentioning

confidence: 99%

Towards a measurement of the spectral runnings

Muñoz

Kovetz

Raccanelli

et al. 2017

J. Cosmol. Astropart. Phys.

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Single-field slow-roll inflation predicts a nearly scale-free power spectrum of perturbations, as observed at the scales accessible to current cosmological experiments. This spectrum is slightly red, showing a tilt (1 − ns) ∼ 0.04. A direct consequence of this tilt are nonvanishing runnings αs = dns/d log k, and βs = dαs/d log k, which in the minimal inflationary scenario should reach absolute values of 10 −3 and 10 −5 , respectively. In this work we calculate how well future surveys can measure these two runnings. We consider a Stage-4 (S4) CMB experiment and show that it will be able to detect significant deviations from the inflationary prediction for αs, although not for βs. Adding to the S4 CMB experiment the information from a WFIRST-like or a DESI-like survey improves the sensitivity to the runnings by ∼ 20%, and 30%, respectively. A spectroscopic survey with a billion objects, such as the SKA, will add enough information to the S4 measurements to allow a detection of αs = 10 −3 , required to probe the single-field slow-roll inflationary paradigm. We show that only a very-futuristic interferometer targeting the dark ages will be capable of measuring the minimal inflationary prediction for βs. The results of other probes, such as a stochastic background of gravitational waves observable by LIGO, the Ly-α forest, and spectral distortions, are shown for comparison. Finally, we study the claims that large values of βs, if extrapolated to the smallest scales, can produce primordial black holes of tens of solar masses, which we show to be easily testable by the S4 CMB experiment.

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Section: -Cmmentioning

confidence: 99%

Towards a measurement of the spectral runnings

Muñoz

Kovetz

Raccanelli

et al. 2017

J. Cosmol. Astropart. Phys.

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“…All of the data used for this paper were taken on the MWA-32T system. This system has since been upgraded to a 128-tile instrument (MWA-128T; Tingay et al [47], Bowman et al [48]), but in this paper we focus exclusively on MWA-32T data, reserving the MWA-128T data for future work.…”

Section: A Description Of Observationsmentioning

confidence: 99%

Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data

et al. 2014

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We present techniques for bridging the gap between idealized inverse covariance weighted quadratic estimation of 21 cm power spectra and the real-world challenges presented universally by interferometric observation. By carefully evaluating various estimators and adapting our techniques for large but incomplete data sets, we develop a robust power spectrum estimation framework that preserves the so-called "Epoch of Reionization (EoR) window" and keeps track of estimator errors and covariances. We apply our method to observations from the 32-tile prototype of the Murchinson Widefield Array to demonstrate the importance of a judicious analysis technique. Lastly, we apply our method to investigate the dependence of the clean EoR window on frequency-especially the frequency dependence of the so-called "wedge" feature-and establish upper limits on the power spectrum from z ¼ 6.2 to z ¼ 11:7. Our lowest limit is ΔðkÞ < 0.3 Kelvin at 95% confidence at a comoving scale k ¼ 0.046 Mpc −1 and z ¼ 9.5.

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“…A range of existing radio interferometers such as the Low Frequency Array (LOFAR) 1 [43,44], the Precision Array for Probing the Epoch of Reionization (PAPER) 2 [45], and the Murchison Widefield Array (MWA) 3 [46,47] have dedicated substantial resources and efforts to detect fluctuations in the 21-cm signal from the EoR. In parallel, several ongoing experiments such as EDGES [48], SARAS [49], BigHorns [50], SciHi [51] and LEDA [52] strive to detect the global (i.e.…”

Section: Introductionmentioning

confidence: 99%

Fuzzy dark matter at cosmic dawn: new 21-cm constraints

Nebrin

Ghara

Mellema

2019

J. Cosmol. Astropart. Phys.

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Potential small-scale discrepancies in the picture of galaxy formation painted by the ΛCDM paradigm have led to considerations of modified dark matter models. One such dark matter model that has recently attracted much attention is fuzzy dark matter (FDM). In FDM models, the dark matter is envisaged to be an ultra-light scalar field with a particle mass m FDM ∼ 10 −22 eV. This yields astronomically large de Broglie wavelengths which can suppress small-scale structure formation and give rise to the observed kpc-sized density cores in dwarf galaxies. We investigate the evolution of the 21-cm signal during Cosmic Dawn and the Epoch of Reionization (EoR) in ΛFDM cosmologies using analytical models. The delay in source formation and the absence of small halos in ΛFDM significantly postpone the Lyα coupling, heating, as well as the reionization of the neutral hydrogen of the intergalactic medium. As a result, the absorption feature in the evolution of the global 21-cm signal has a significantly smaller full width at half maximum (∆z 3), than ΛCDM (∆z 6). This alone rules out m FDM < 6 × 10 −22 eV as a result of the 2σ lower limit ∆z 4 from EDGES High-Band. As a result, ΛFDM is not a viable solution to the potential small-scale problems facing ΛCDM. Finally, we show that any detection of the 21-cm signal at redshifts z > 14 by interferometers such as the SKA can also exclude ΛFDM models.

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Science with the Murchison Widefield Array

Cited by 3 publications

References 0 publications

Towards a measurement of the spectral runnings

Towards a measurement of the spectral runnings

Overcoming real-world obstacles in 21 cm power spectrum estimation: A method demonstration and results from early Murchison Widefield Array data

Fuzzy dark matter at cosmic dawn: new 21-cm constraints

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