Angular power spectra of 610 MHz radio halos show excess power-law fluctuations only in Abell 2744, requiring multiplicative C_ℓ ∝ ℓ^{-3} structure atop an exponential profile and consistent with ICM turbulence.
21 cm observation of LSS at z~1 Instrument sensitivity and foreground subtraction
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abstract
Large Scale Structures (LSS) in the universe can be traced using the neutral atomic hydrogen HI through its 21cm emission. Such a 3D matter distribution map can be used to test the Cosmological model and to constrain the Dark Energy properties or its equation of state. A novel approach, called intensity mapping can be used to map the HI distribution, using radio interferometers with large instantaneous field of view and waveband. In this paper, we study the sensitivity of different radio interferometer configurations, or multi-beam instruments for the observation of large scale structures and BAO oscillations in 21cm and we discuss the problem of foreground removal. For each configuration, we determine instrument response by computing the (u,v) or Fourier angular frequency plane coverage using visibilities. The (u,v) plane response is the noise power spectrum, hence the instrument sensitivity for LSS P(k) measurement. We describe also a simple foreground subtraction method to separate LSS 21 cm signal from the foreground due to the galactic synchrotron and radio sources emission. We have computed the noise power spectrum for different instrument configuration as well as the extracted LSS power spectrum, after separation of 21cm-LSS signal from the foregrounds. We have also obtained the uncertainties on the Dark Energy parameters for an optimized 21 cm BAO survey. We show that a radio instrument with few hundred simultaneous beams and a collecting area of ~10000 m^2 will be able to detect BAO signal at redshift z ~ 1 and will be competitive with optical surveys.
years
2026 4representative citing papers
Updated SKAO-AA4 forecasts show multi-tracer HI+galaxy analyses can reach σ(f_local_NL)≲1 and improve αs bounds by tens of percent when combined with future CMB, while foregrounds and GR light-cone effects remain the main systematics.
Comparison of Galactic magnetic field models to polarized synchrotron observations shows good agreement on angles but poor match on intensity, indicating local foreground structures must be incorporated.
A review chapter summarizing advances in map-making and component-separation techniques for 21-cm intensity mapping to address systematics and foreground contamination in simulations for SKA-Mid.
citing papers explorer
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Intensity fluctuations of radio halo in galaxy cluster: Insights from power spectrum estimation
Angular power spectra of 610 MHz radio halos show excess power-law fluctuations only in Abell 2744, requiring multiplicative C_ℓ ∝ ℓ^{-3} structure atop an exponential profile and consistent with ICM turbulence.
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Beyond {\Lambda}CDM with the SKA Observatory -- II: Unveiling the Secrets of the Early Universe
Updated SKAO-AA4 forecasts show multi-tracer HI+galaxy analyses can reach σ(f_local_NL)≲1 and improve αs bounds by tens of percent when combined with future CMB, while foregrounds and GR light-cone effects remain the main systematics.
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A comparison between Galactic magnetic field models and polarized synchrotron emission with C-BASS at 4.76 GHz and S-PASS at 2.3 GHz
Comparison of Galactic magnetic field models to polarized synchrotron observations shows good agreement on angles but poor match on intensity, indicating local foreground structures must be incorporated.
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Methodological Frontiers in 21-cm Intensity Mapping: the Treatment of Systematics and Foreground Contamination
A review chapter summarizing advances in map-making and component-separation techniques for 21-cm intensity mapping to address systematics and foreground contamination in simulations for SKA-Mid.