2017) are designed to detect the EoR 21-cm power spectrum with higher sensitivity. 2015) and the Hydrogen Epoch of Reionization Array (HERA 5 DeBoer et al. Also, future experiment like the Square Kilometer Array (SKA1 LOW 4 Koopmans et al. 1991) are aiming to detect the 21-cm power spectrum from the Epoch of Reionization (EoR). 2013) and the Giant Metrewave Radio Telescope (GMRT Swarup et al. 2013), the Murchison Wide-field Array (MWA 3 Bowman et al. 2010), the Low Frequency Array (LOFAR 2 var Haarlem et al. Backer Precision Array to Probe the Epoch of Reionization (PAPER 1 Parsons et al.
Several ongoing experiments such as Donald C. Bharadwaj & Ali 2005 Furlanetto, Oh & Briggs 2006 Morales & Wyithe 2010 Prichard & Loeb 2012 Mellema et al. Measurements of the cosmological redshifted neutral hydrogen (H i) 21-cm power spectrum can be used to probe the Universe over a large redshift range 0 < z ≲ 200 (e.g. Methods: data analysis, methods: statistical, techniques: interferometric, galaxies: ISM 1 INTRODUCTION This indicates that the statistical properties of ISM turbulence possibly differ in different regions of the galaxy. We find that the slope of the measured C ℓ in the outer region is significantly different as compared with the inner region. We have applied the ITGE to estimate the C ℓ of HI 21-cm emission from different regions of the galaxy NGC 628. We validate the ITGE using realistic VLA simulations at 1.4 GHz.
It also calculates the noise bias internally and exactly subtracts this out to give an unbiased estimate of C ℓ. The ITGE deals with gridded data, hence it is computationally efficient. In the context of the ISM in external galaxies, this is useful to separately estimate the C ℓ of different parts of the galaxy. In the context of the cosmological H i 21-cm signal, this is useful for masking out the sky signal from specific directions which have strong residual foregrounds.
The ITGE allows us to modulate the sky response through a window function which is implemented in the image plane, and it is possible to choose a wide variety of window functions. We present the Image-based Tapered Gridded Estimator (ITGE) to measure the angular power spectrum ( C ℓ) of the sky signal directly from the visibilities measured in radio-interferometric observations.