Search Results - "Yatawatta, S."

Adaptive weighting in radio interferometric imaging by Yatawatta, S.

“…Radio interferometers observe the Fourier space of the sky, at locations determined by the array geometry. Before a real space image is constructed by a…”
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Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR by Mertens, F G, Mevius, M, Koopmans, L V E, Offringa, A R, Mellema, G, Zaroubi, S, Brentjens, M A, Gan, H, Gehlot, B K, Pandey, V N, Sardarabadi, A M, Vedantham, H K, Yatawatta, S, Asad, K M B, Ciardi, B, Chapman, E, Gazagnes, S, Ghara, R, Ghosh, A, Giri, S K, Iliev, I T, Jelić, V, Kooistra, R, Mondal, R, Schaye, J, Silva, M B

“…ABSTRACT A new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency…”
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Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations by Ghara, R, Giri, S K, Mellema, G, Ciardi, B, Zaroubi, S, Iliev, I T, Koopmans, L V E, Chapman, E, Gazagnes, S, Gehlot, B K, Ghosh, A, Jelić, V, Mertens, F G, Mondal, R, Schaye, J, Silva, M B, Asad, K M B, Kooistra, R, Mevius, M, Offringa, A R, Pandey, V N, Yatawatta, S

“…ABSTRACT We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift ≈ 9.1 using new upper limits on the 21-cm…”
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The first power spectrum limit on the 21-cm signal of neutral hydrogen during the Cosmic Dawn at z = 20–25 from LOFAR by Gehlot, B K, Mertens, F G, Koopmans, L V E, Brentjens, M A, Zaroubi, S, Ciardi, B, Ghosh, A, Hatef, M, Iliev, I T, Jelić, V, Kooistra, R, Krause, F, Mellema, G, Mevius, M, Mitra, M, Offringa, A R, Pandey, V N, Sardarabadi, A M, Schaye, J, Silva, M B, Vedantham, H K, Yatawatta, S

“…ABSTRACT Observations of the redshifted 21-cm hyperfine line of neutral hydrogen from early phases of the Universe such as Cosmic Dawn and the Epoch of…”
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Robust radio interferometric calibration using the t-distribution by Kazemi, S., Yatawatta, S.

“…A major stage of radio interferometric data processing is calibration or the estimation of systematic errors in the data and the correction for such errors. A…”
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The AARTFAAC Cosmic Explorer: observations of the 21-cm power spectrum in the EDGES absorption trough by Gehlot, B K, Mertens, F G, Koopmans, L V E, Offringa, A R, Shulevski, A, Mevius, M, Brentjens, M A, Kuiack, M, Pandey, V N, Rowlinson, A, Sardarabadi, A M, Vedantham, H K, Wijers, R A M J, Yatawatta, S, Zaroubi, S

“…ABSTRACT The 21-cm absorption feature reported by the EDGES collaboration is several times stronger than that predicted by traditional astrophysical models. If…”
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Upper Limits on the 21 cm Epoch of Reionization Power Spectrum from One Night with LOFAR by Patil, A. H., Yatawatta, S., Koopmans, L. V. E., Bruyn, A. G. de, Brentjens, M. A., Zaroubi, S., Asad, K. M. B., Hatef, M., Jeli, V., Mevius, M., Offringa, A. R., Pandey, V. N., Vedantham, H., Abdalla, F. B., Brouw, W. N., Chapman, E., Ciardi, B., Gehlot, B. K., Ghosh, A., Harker, G., Iliev, I. T., Kakiichi, K., Majumdar, S., Mellema, G., Silva, M. B., Schaye, J., Vrbanec, D., Wijnholds, S. J.

“…We present the first limits on the Epoch of Reionization 21 cm H i power spectra, in the redshift range z = 7.9-10.6, using the Low-Frequency Array (LOFAR)…”
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Probing ionospheric structures using the LOFAR radio telescope by Mevius, M., Tol, S., Pandey, V. N., Vedantham, H. K., Brentjens, M. A., Bruyn, A. G., Abdalla, F. B., Asad, K. M. B., Bregman, J. D., Brouw, W. N., Bus, S., Chapman, E., Ciardi, B., Fernandez, E. R., Ghosh, A., Harker, G., Iliev, I. T., Jelić, V., Kazemi, S., Koopmans, L. V. E., Noordam, J. E., Offringa, A. R., Patil, A. H., Weeren, R. J., Wijnholds, S., Yatawatta, S., Zaroubi, S.

“…LOFAR is the LOw‐Frequency Radio interferometer ARray located at midlatitude (52°53′N). Here we present results on ionospheric structures derived from 29 LOFAR…”
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Polarization leakage in epoch of reionization windows – I. Low Frequency Array observations of the 3C196 field by Asad, K. M. B., Koopmans, L. V. E., Jelić, V., Pandey, V. N., Ghosh, A., Abdalla, F. B., Bernardi, G., Brentjens, M. A., de Bruyn, A. G., Bus, S., Ciardi, B., Chapman, E., Daiboo, S., Fernandez, E. R., Harker, G., Iliev, I. T., Jensen, H., Martinez-Rubi, O., Mellema, G., Mevius, M., Offringa, A. R., Patil, A. H., Schaye, J., Thomas, R. M., van der Tol, S., Vedantham, H. K., Yatawatta, S., Zaroubi, S.

“…Detection of the 21-cm signal coming from the epoch of reionization (EoR) is challenging especially because, even after removing the foregrounds, the residual…”
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Foreground simulations for the LOFAR–epoch of reionization experiment by Jelić, V., Zaroubi, S., Labropoulos, P., Thomas, R. M., Bernardi, G., Brentjens, M. A., De Bruyn, A. G., Ciardi, B., Harker, G., Koopmans, L. V. E., Pandey, V. N., Schaye, J., Yatawatta, S.

“…Future high-redshift 21-cm experiments will suffer from a high degree of contamination, due both to astrophysical foregrounds and to non-astrophysical and…”
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A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data by Mevius, M, Mertens, F, Koopmans, L V E, Offringa, A R, Yatawatta, S, Brentjens, M A, Chapman, E, Ciardi, B, Gan, H, Gehlot, B K, Ghara, R, Ghosh, A, Giri, S K, Iliev, I T, Mellema, G, Pandey, V N, Zaroubi, S

“…ABSTRACT We investigate systematic effects in direction-dependent gain calibration in the context of the Low-Frequency Array (LOFAR) 21-cm Epoch of…”
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Wide-field LOFAR-LBA power-spectra analyses: impact of calibration, polarization leakage, and ionosphere by Gehlot, B K, Koopmans, L V E, de Bruyn, A G, Zaroubi, S, Brentjens, M A, Asad, K M B, Hatef, M, Jelić, V, Mevius, M, Offringa, A R, Pandey, V N, Yatawatta, S

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Clustered calibration: an improvement to radio interferometric direction-dependent self-calibration by Kazemi, S., Yatawatta, S., Zaroubi, S.

“…The new generation of radio synthesis arrays, such as Low Frequency Array and Square Kilometre Array, have been designed to surpass existing arrays in terms of…”
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A novel radio imaging method for physical spectral index modelling by Ceccotti, E, Offringa, A R, Koopmans, L V E, Timmerman, R, Brackenhoff, S A, Gehlot, B K, Mertens, F G, Munshi, S, Pandey, V N, van Weeren, R J, Yatawatta, S, Zaroubi, S

“…ABSTRACT We present a new method, called ‘forced-spectrum fitting’, for physically based spectral modelling of radio sources during deconvolution. This…”
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Radio interferometric calibration using the SAGE algorithm by Kazemi, S., Yatawatta, S., Zaroubi, S., Lampropoulos, P., de Bruyn, A. G., Koopmans, L. V. E., Noordam, J.

“…The aim of the new generation of radio synthesis arrays such as LOw Frequency ARray (LOFAR) and Square Kilometre Array (SKA) is to achieve much higher…”
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Probing reionization with LOFAR using 21-cm redshift space distortions by Jensen, Hannes, Datta, Kanan K., Mellema, Garrelt, Chapman, Emma, Abdalla, Filipe B., Iliev, Ilian T., Mao, Yi, Santos, Mario G., Shapiro, Paul R., Zaroubi, Saleem, Bernardi, G., Brentjens, M. A., de Bruyn, A. G., Ciardi, B., Harker, G. J. A., Jeli, V., Kazemi, S., Koopmans, L. V. E., Labropoulos, P., Martinez, O., Offringa, A. R., Pandey, V. N., Schaye, J., Thomas, R. M., Veligatla, V., Vedantham, H., Yatawatta, S.

“…One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral…”
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Polarization leakage in epoch of reionization windows – II. Primary beam model and direction-dependent calibration by Asad, K. M. B., Koopmans, L. V. E., Jelić, V., Ghosh, A., Abdalla, F. B., Brentjens, M. A., de Bruyn, A. G., Ciardi, B., Gehlot, B. K., Iliev, I. T., Mevius, M., Pandey, V. N., Yatawatta, S., Zaroubi, S.

“…Leakage of diffuse polarized emission into Stokes I caused by the polarized primary beam of the instrument might mimic the spectral structure of the 21-cm…”
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Radio interferometric calibration via ordered-subsets algorithms: OS-LS and OS-SAGE calibrations by Kazemi, S., Yatawatta, S., Zaroubi, S.

“…The main objective of this work is to accelerate the maximum likelihood (ML) estimation procedure in radio interferometric calibration. We introduce the…”
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Imaging neutral hydrogen on large scales during the Epoch of Reionization with LOFAR by Zaroubi, S., de Bruyn, A. G., Harker, G., Thomas, R. M., Labropolous, P., Jelić, V., Koopmans, L. V. E., Brentjens, M. A., Bernardi, G., Ciardi, B., Daiboo, S., Kazemi, S., Martinez‐Rubi, O., Mellema, G., Offringa, A. R., Pandey, V. N., Schaye, J., Veligatla, V., Vedantham, H., Yatawatta, S.

“…ABSTRACT The first generation of redshifted 21 cm detection experiments, carried out with arrays like Low Frequency Array (LOFAR), Murchison Widefield Array…”
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LOFAR insights into the epoch of reionization from the cross-power spectrum of 21 cm emission and galaxies by Wiersma, R. P. C., Ciardi, B., Thomas, R. M., Harker, G. J. A., Zaroubi, S., Bernardi, G., Brentjens, M., de Bruyn, A. G., Daiboo, S., Jelic, V., Kazemi, S., Koopmans, L. V. E., Labropoulos, P., Martinez, O., Mellema, G., Offringa, A., Pandey, V. N., Schaye, J., Veligatla, V., Vedantham, H., Yatawatta, S.

“…Using a combination of N-body simulations, semi-analytic models and radiative transfer calculations, we have estimated the theoretical cross-power spectrum…”
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