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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2021

1/f noise analysis for FAST H i intensity mapping drift-scan experiment

Wenkai Hu
Yichao Li
  • Fonction : Auteur
Fengquan Wu
  • Fonction : Auteur
Bo Zhang
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Ming Zhu
  • Fonction : Auteur
Shifan Zuo
  • Fonction : Auteur
Guilaine Lagache
Yin-Zhe Ma
Mario Santos
Xuelei Chen

Résumé

ABSTRACT We investigate the 1/f noise of the Five-hundred-meter Aperture Spherical Telescope (FAST) receiver system using drift-scan data from an intensity mapping pilot survey. All the 19 beams have 1/f fluctuations with similar structures. Both the temporal and the 2D power spectrum densities are estimated. The correlations directly seen in the time series data at low frequency f are associated with the sky signal, perhaps due to a coupling between the foreground and the system response. We use singular value decomposition (SVD) to subtract the foreground. By removing the strongest components, the measured 1/f noise power can be reduced significantly. With 20 modes subtraction, the knee frequency of the 1/f noise in a 10-MHz band is reduced to $1.8 \times 10^{-3}\, {\rm Hz}$, well below the thermal noise over 500-s time-scale. The 2D power spectra show that the 1/f-type variations are restricted to a small region in the time-frequency space and the correlations in frequency can be suppressed with SVD modes subtraction. The residual 1/f noise after the SVD mode subtraction is uncorrelated in frequency, and a simple noise diode frequency-independent calibration of the receiver gain at 8-s interval does not affect the results. The 1/f noise can be important for H i intensity mapping, we estimate that the 1/f noise has a knee frequency (fk) ∼ 6 × 10−4 Hz, and time and frequency correlation spectral indices (α) ∼ 0.65, (β) ∼ 0.8 after the SVD subtraction of 30 modes. This can bias the H i power spectrum measurement by 10 per cent.
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Dates et versions

hal-03562528 , version 1 (20-04-2023)

Identifiants

Citer

Wenkai Hu, Yichao Li, Yougang Wang, Fengquan Wu, Bo Zhang, et al.. 1/f noise analysis for FAST H i intensity mapping drift-scan experiment. Monthly Notices of the Royal Astronomical Society, 2021, 508 (2), pp.2897-2909. ⟨10.1093/mnras/stab2728⟩. ⟨hal-03562528⟩
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