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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2411.04193 |
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| _version_ | 1866912532665466880 |
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| author | Elder, Katherine Jacobs, Daniel C. Kovaleva, Maria |
| author_facet | Elder, Katherine Jacobs, Daniel C. Kovaleva, Maria |
| contents | Measurement of the power spectrum of high redshift 21 cm emission from neutral hydrogen probes the formation of the first luminous objects and the ionization of intergalactic medium by the first stars. However, the 21 cm signal at these redshifts is orders of magnitude fainter than astrophysical foregrounds, making it challenging to measure. Power spectrum techniques may be able to avoid these foregrounds by extracting foreground-free Fourier modes, but this is exacerbated by instrumental systematics that can add spectral structure to the data, leaking foreground power to the foreground-free Fourier modes. It is therefore imperative that any instrumental systematic effects are properly understood and mitigated. One such systematic occurs when neighboring antennas have undesired coupling. A systematic in Phase II data from the MWA was identified which manifests as excess correlation in the visibilities. One possible explanation for such an effect is mutual coupling between antennas. A numerical electromagnetic software simulation of the antenna beam using FEKO has been built to estimate the amplitude of this effect for multiple antennas in the MWA. The numerical model predicts an amplitude which exceeds the requirement to avoid spreading the foreground. More work is necessary to better validate the required level of coupling and to verify that approximations did not under estimate the level of coupling. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_04193 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Investigating mutual coupling in the MWA Phase II compact array Elder, Katherine Jacobs, Daniel C. Kovaleva, Maria Instrumentation and Methods for Astrophysics Measurement of the power spectrum of high redshift 21 cm emission from neutral hydrogen probes the formation of the first luminous objects and the ionization of intergalactic medium by the first stars. However, the 21 cm signal at these redshifts is orders of magnitude fainter than astrophysical foregrounds, making it challenging to measure. Power spectrum techniques may be able to avoid these foregrounds by extracting foreground-free Fourier modes, but this is exacerbated by instrumental systematics that can add spectral structure to the data, leaking foreground power to the foreground-free Fourier modes. It is therefore imperative that any instrumental systematic effects are properly understood and mitigated. One such systematic occurs when neighboring antennas have undesired coupling. A systematic in Phase II data from the MWA was identified which manifests as excess correlation in the visibilities. One possible explanation for such an effect is mutual coupling between antennas. A numerical electromagnetic software simulation of the antenna beam using FEKO has been built to estimate the amplitude of this effect for multiple antennas in the MWA. The numerical model predicts an amplitude which exceeds the requirement to avoid spreading the foreground. More work is necessary to better validate the required level of coupling and to verify that approximations did not under estimate the level of coupling. |
| title | Investigating mutual coupling in the MWA Phase II compact array |
| topic | Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2411.04193 |