Zobrazeno 1 - 10
of 88
pro vyhledávání: '"Ghara, R"'
Autor:
Munshi, S., Mertens, F. G., Koopmans, L. V. E., Offringa, A. R., Semelin, B., Aubert, D., Barkana, R., Bracco, A., Brackenhoff, S. A., Cecconi, B., Ceccotti, E., Corbel, S., Fialkov, A., Gehlot, B. K., Ghara, R., Girard, J. N., Grießmeier, J. M., Höfer, C., Hothi, I., Mériot, R., Mevius, M., Ocvirk, P., Shaw, A. K., Theureau, G., Yatawatta, S., Zarka, P., Zaroubi, S.
Publikováno v:
A&A 681, A62 (2024)
The redshifted 21 cm signal from neutral hydrogen is a direct probe of the physics of the early universe and has been an important science driver of many present and upcoming radio interferometers. In this study we use a single night of observations
Externí odkaz:
http://arxiv.org/abs/2311.05364
Autor:
Gan, H., Mertens, F. G., Koopmans, L. V. E., Offringa, A. R., Mevius, M., Pandey, V. N., Brackenhoff, S. A., Ceccotti, E., Ciardi, B., Gehlot, B. K., Ghara, R., Giri, S. K., Iliev, I. T., Munshi, S.
Publikováno v:
A&A 669, A20 (2023)
Detecting the 21-cm signal from the Epoch of Reionisation (EoR) is challenging due to the strong astrophysical foregrounds, ionospheric effects, radio frequency interference and instrumental effects. Understanding and calibrating these effects are cr
Externí odkaz:
http://arxiv.org/abs/2209.07854
Autor:
Gan, H., Koopmans, L. V. E, Mertens, F. G., Mevius, M., Offringa, A. R., Ciardi, B., Gehlot, B. K., Ghara, R., Ghosh, A., Giri, S. K., Iliev, I. T., Mellema, G., Pandey, V. N., Zaroubi, S.
Publikováno v:
A&A 663, A9 (2022)
The detection of the 21 cm signal of neutral hydrogen from the Epoch of Reionization (EoR) is challenging due to bright foreground sources, radio frequency interference (RFI), the ionosphere, and instrumental effects. Even after correcting for these
Externí odkaz:
http://arxiv.org/abs/2203.02345
Autor:
Gehlot, B. K., Koopmans, L. V. E., Offringa, A. R., Gan, H., Ghara, R., Giri, S. K., Kuiack, M., Mertens, F. G., Mevius, M., Mondal, R., Pandey, V. N., Shulevski, A., Wijers, R. A. M. J., Yatawatta, S.
Publikováno v:
A&A 662, A97 (2022)
Aims: Contamination from bright diffuse Galactic thermal and non-thermal radio emission poses crucial challenges in experiments aiming to measure the 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization. If not included in
Externí odkaz:
http://arxiv.org/abs/2112.00721
Autor:
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.
Publikováno v:
MNRAS 2021
We investigate systematic effects in direction dependent gain calibration in the context of the Low-Frequency Array (LOFAR) 21-cm Epoch of Reionization (EoR) experiment. The LOFAR EoR Key Science Project aims to detect the 21-cm signal of neutral hyd
Externí odkaz:
http://arxiv.org/abs/2111.02537
Autor:
Hothi, Ian, Chapman, Emma, Pritchard, Jonathan R., Mertens, F. G., Koopmans, L. V. E, Ciardi, B., Gehlot, B. K., Ghara, R., Ghosh, A., Giri, S. K., Iliev, I. T., Jelić, V., Zaroubi, S.
We compare various foreground removal techniques that are being utilised to remove bright foregrounds in various experiments aiming to detect the redshifted 21cm signal of neutral hydrogen from the Epoch of Reionization. In this work, we test the per
Externí odkaz:
http://arxiv.org/abs/2011.01284
Autor:
Mondal, R., Fialkov, A., Fling, C., Iliev, I. T., Barkana, R., Ciardi, B., Mellema, G., Zaroubi, S., Koopmans, L. V. E, Mertens, F. G., Gehlot, B. K., Ghara, R., Ghosh, A., Giri, S. K., Offringa, A., Pandey, V. N.
Publikováno v:
Monthly Notices of the Royal Astronomical Society, Volume 498, Issue 3, November 2020, Pages 4178-4191
The ARCADE2 and LWA1 experiments have claimed an excess over the Cosmic Microwave Background (CMB) at low radio frequencies. If the cosmological high-redshift contribution to this radio background is between 0.1% and 22% of the CMB at 1.42 GHz, it co
Externí odkaz:
http://arxiv.org/abs/2004.00678
Autor:
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., Jelic, 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.
We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift $\approx$ 9.1 using new upper limits on the 21-cm power spectrum measured by the LOFAR radio-telescope and a prior on the ionized fraction at tha
Externí odkaz:
http://arxiv.org/abs/2002.07195
Autor:
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.
A new upper limit on the 21-cm signal power spectrum at a redshift of $z \approx 9.1$ is presented, based on 141 hours of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally-smooth gain-cal
Externí odkaz:
http://arxiv.org/abs/2002.07196
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