Reionisation & Cosmic Dawn Astrophysics from the Square Kilometre Array: Impact of Observing Strategies

Abstract Interferometry of the cosmic 21-cm signal is set to revolutionise our understanding of the Epoch of Reionisation (EoR) and the Cosmic Dawn (CD). The culmination of ongoing efforts will be the upcoming Square Kilometre Array (SKA), which will provide tomography of the 21-cm signal from the first billion years of our Universe. Using a galaxy formation model informed by high-z luminosity functions, here we forecast the accuracy with which the first phase of SKA-low (SKA1-low) can constrain the properties of the unseen galaxies driving the astrophysics of the EoR and CD. We consider three observing strategies: (i) deep (1000h on a single field); (ii) medium-deep (100hr on 10 independent fields); and (iii) shallow (10hr on 100 independent fields). Using the 21-cm power spectrum as a summary statistic, and conservatively only using the 21-cm signal above the foreground wedge, we predict that all three observing strategies should recover astrophysical parameters to a fractional precision of ∼0.1 – 10 per cent. The reionisation history is recovered to an uncertainty of $\Delta z \mathrel {\lesssim}0.1$ (1σ) for the bulk of its duration. The medium-deep strategy, balancing thermal noise against cosmic variance, results in the tightest constraints, slightly outperforming the deep strategy. The shallow observational strategy performs the worst, with up to a ∼10 – 60 per cent increase in the recovered uncertainty. We note, however, that non-Gaussian summary statistics, tomography, as well as unbiased foreground removal would likely favour the deep strategy.

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Cosmological evolution of the AGN kinetic luminosity function

Proceedings of the International Astronomical Union ◽

10.1017/s174392130700470x ◽

2006 ◽

Vol 2 (S238) ◽

pp. 65-70

Author(s):

Andrea Merloni ◽

Sebastian Heinz

Keyword(s):

Galaxy Formation ◽

Luminosity Function ◽

Cosmological Evolution ◽

Energy Output ◽

Theoretical Assumption ◽

X Ray ◽

Spectrum Radio ◽

Luminosity Functions ◽

Jet Power ◽

Joint Evolution

AbstractWe present a first attempt to derive the cosmological evolution of the kinetic luminosity function of AGN based on the joint evolution of the flat spectrum radio and hard X-ray selected AGN luminosity functions. An empirical correlation between jet power and radio core luminosity is found, which is consistent with the theoretical assumption that, below a certain Eddington ratio, SMBH accrete in a radiatively inefficient way, while most of the energy output is in the form of kinetic energy.We show how the redshift evolution of the kinetic power density from such a low-ṁ mode of accretion makes it a good candidate to explain the so-called “radio mode” of AGN feedback as outlined in many galaxy formation schemes.

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A generalized non-Gaussian consistency relation for single field inflation

Journal of Cosmology and Astroparticle Physics ◽

10.1088/1475-7516/2018/05/024 ◽

2018 ◽

Vol 2018 (05) ◽

pp. 024-024 ◽

Cited By ~ 21

Author(s):

Rafael Bravo ◽

Sander Mooij ◽

Gonzalo A. Palma ◽

Bastián Pradenas

Keyword(s):

Consistency Relation ◽

Single Field ◽

Non Gaussian

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Optimal signal processing algorithm at the background of non-Gaussian flicker noise

ITM Web of Conferences ◽

10.1051/itmconf/20193004016 ◽

2019 ◽

Vol 30 ◽

pp. 04016 ◽

Cited By ~ 1

Author(s):

Alexander Parshin ◽

Yury Parshin

Keyword(s):

Signal Processing ◽

Information Transfer ◽

Thermal Noise ◽

Flicker Noise ◽

Noise Model ◽

Processing Algorithm ◽

Signal Processing Algorithm ◽

Ultra Low Power ◽

Non Gaussian ◽

Optimal Signal

The problem of receiving and processing ultra-low-power signals of information transmission systems is being solved. High requirements for energy efficiency on the one hand and a low information transfer rate allows the use of signals with a small spectrum width, including flicker noise spectral regions. A non-Gaussian flicker noise model is used based on a stochastic differential equation with a nonlinear drift coefficient. An optimal signal processing algorithm is being developed against the background of the sum of flicker noise and thermal noise based on an estimated-correlation-compensation approach. The analysis of the effectiveness of optimal signal processing against a background of non-Gaussian flicker noise and thermal noise is carried out.

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Prediction of H α and [O iii] emission line galaxy number counts for future galaxy redshift surveys

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2844 ◽

2019 ◽

Vol 490 (3) ◽

pp. 3667-3678 ◽

Cited By ~ 1

Author(s):

Zhongxu Zhai ◽

Andrew Benson ◽

Yun Wang ◽

Gustavo Yepes ◽

Chia-Hsun Chuang

Keyword(s):

Emission Line ◽

Galaxy Formation ◽

Luminosity Function ◽

Large Scale ◽

High Redshift ◽

Flux Ratio ◽

Formation Model ◽

Line Flux ◽

Emission Line Galaxies ◽

Number Counts

ABSTRACT We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and [O iii] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [O iii] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and [O iii] emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of [O iii] emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/[O iii] within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/[O iii] flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.

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Source counts and confusion at 72–231 MHz in the MWA GLEAM survey

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2018.52 ◽

2019 ◽

Vol 36 ◽

Cited By ~ 6

Author(s):

T. M. O. Franzen ◽

T. Vernstrom ◽

C. A. Jackson ◽

N. Hurley-Walker ◽

R. D. Ekers ◽

...

Keyword(s):

Thermal Noise ◽

Low Frequency ◽

Radio Continuum ◽

Large Area ◽

Design Study ◽

Array Design ◽

Square Kilometre Array ◽

Noise Limit ◽

Murchison Widefield Array ◽

Extended Emission

Abstract The GaLactic and Extragalactic All-sky Murchison Widefield Array survey is a radio continuum survey at 72–231 MHz of the whole sky south of declination +30º, carried out with the Murchison Widefield Array. In this paper, we derive source counts from the GaLactic and Extragalactic All-sky Murchison data at 200, 154, 118, and 88 MHz, to a flux density limit of 50, 80, 120, and 290 mJy respectively, correcting for ionospheric smearing, incompleteness and source blending. These counts are more accurate than other counts in the literature at similar frequencies as a result of the large area of sky covered and this survey’s sensitivity to extended emission missed by other surveys. At S154 MHz > 0.5 Jy, there is no evidence of flattening in the average spectral index (α ≈ −0.8 where S ∝ vα) towards the lower frequencies. We demonstrate that the Square Kilometre Array Design Study model by Wilman et al. significantly underpredicts the observed 154-MHz GaLactic and Extragalactic All-sky Murchison counts, particularly at the bright end. Using deeper Low-Frequency Array counts and the Square Kilometre Array Design Study model, we find that sidelobe confusion dominates the thermal noise and classical confusion at v ≳ 100 MHz due to both the limited CLEANing depth and the undeconvolved sources outside the field-of-view. We show that we can approach the theoretical noise limit using a more efficient and automated CLEAN algorithm.

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On the origin of dust in galaxy clusters at low-to-intermediate redshift

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa431 ◽

2020 ◽

Vol 493 (2) ◽

pp. 2782-2792

Author(s):

Eda Gjergo ◽

Marco Palla ◽

Francesca Matteucci ◽

Elena Lacchin ◽

Andrea Biviano ◽

...

Keyword(s):

Galaxy Clusters ◽

Galaxy Formation ◽

Spiral Galaxies ◽

Intracluster Medium ◽

Mass Ratio ◽

Luminosity Functions ◽

Galactic Sources ◽

S0 Galaxies ◽

Intermediate Redshift ◽

Detailed Chemical

ABSTRACT Stacked analyses of galaxy clusters at low-to-intermediate redshift show signatures attributable to dust, but the origin of this dust is uncertain. We test the hypothesis that the bulk of cluster dust derives from galaxy ejecta. To do so, we employ dust abundances obtained from detailed chemical evolution models of galaxies. We integrate the dust abundances over cluster luminosity functions (one-slope and two-slope Schechter functions). We consider both a hierarchical scenario of galaxy formation and an independent evolution of the three main galactic morphologies: elliptical/S0, spiral and irregular. We separate the dust residing within galaxies from the dust ejected in the intracluster medium. To the latter, we apply thermal sputtering. The model results are compared to low-to-intermediate redshift observations of dust masses. We find that in any of the considered scenarios, elliptical/S0 galaxies contribute negligibly to the present-time intracluster dust, despite producing the majority of gas-phase metals in galaxy clusters. Spiral galaxies, instead, provide both the bulk of the spatially unresolved dust and of the dust ejected into the intracluster medium. The total dust-to-gas mass ratio in galaxy clusters amounts to 10−4, while the intracluster medium dust-to-gas mass ratio amounts to 10−6 at most. These dust abundances are consistent with the estimates of cluster observations at 0.2 < z < 1. We propose that galactic sources, spiral galaxies in particular, are the major contributors to the cluster dust budget.

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