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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2511.21289 |
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| _version_ | 1866911288169332736 |
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| author | The HERA Collaboration Abdurashidova, Zuhra Adams, Tyrone Aguirre, James E. Baartman, Rushelle Barkana, Rennan Berkhout, Lindsay M. Bernardi, Gianni Billings, Tashalee S. Bizarria, Bruno B. Bowman, Judd D. Breitman, Daniela Bull, Philip Burba, Jacob Byrne, Ruby Carey, Steven Chandra, Rajorshi Sushovan Chen, Kai-Feng Choudhuri, Samir Cox, Tyler DeBoer, David R. Acedo, Eloy de Lera Dexter, Matt Dhandha, Jiten Dillon, Joshua S. Dynes, Scott Eksteen, Nico Ely, John Ewall-Wice, Aaron Fagnoni, Nicolas Fialkov, Anastasia Furlanetto, Steven R. Gale-Sides, Kingsley Garsden, Hugh Gorce, Adelie Gorthi, Deepthi Halday, Ziyaad Hazelton, Bryna J. Hewitt, Jacqueline N. Hickish, Jack Huang, Tian Jacobs, Daniel C. Josaitis, Alec Kern, Nicholas S. Kerrigan, Joshua Kittiwisit, Piyanat Kolopanis, Matthew Lanman, Adam La Plante, Paul Liu, Adrian Ma, Yin-Zhe MacMahon, David H. E. Malan, Lourence Malgas, Cresshim Malgas, Keith Marero, Bradley Martinot, Zachary E. McBride, Lisa Mesinger, Andrei Mirocha, Jordan Mohamed-Hinds, Nicel Molewa, Mathakane Morales, Miguel F. Muñoz, Julian B. Murray, Steven G. Nikolic, Bojan Nuwegeld, Hans Parsons, Aaron R. Pascua, Robert Patra, Nipanjana Pochinda, Simon Qin, Yuxiang Rath, Eleanor Razavi-Ghods, Nima Riley, Daniel Rosie, Kathryn Santos, Mario G. Singh, Saurabh Storer, Dara Swarts, Hilton Tan, Jianrong Thélie, Emilie van Wyngaarden, Pieter Wilensky, Michael J. Williams, Peter K. G. Zheng, Haoxuan |
| author_facet | The HERA Collaboration Abdurashidova, Zuhra Adams, Tyrone Aguirre, James E. Baartman, Rushelle Barkana, Rennan Berkhout, Lindsay M. Bernardi, Gianni Billings, Tashalee S. Bizarria, Bruno B. Bowman, Judd D. Breitman, Daniela Bull, Philip Burba, Jacob Byrne, Ruby Carey, Steven Chandra, Rajorshi Sushovan Chen, Kai-Feng Choudhuri, Samir Cox, Tyler DeBoer, David R. Acedo, Eloy de Lera Dexter, Matt Dhandha, Jiten Dillon, Joshua S. Dynes, Scott Eksteen, Nico Ely, John Ewall-Wice, Aaron Fagnoni, Nicolas Fialkov, Anastasia Furlanetto, Steven R. Gale-Sides, Kingsley Garsden, Hugh Gorce, Adelie Gorthi, Deepthi Halday, Ziyaad Hazelton, Bryna J. Hewitt, Jacqueline N. Hickish, Jack Huang, Tian Jacobs, Daniel C. Josaitis, Alec Kern, Nicholas S. Kerrigan, Joshua Kittiwisit, Piyanat Kolopanis, Matthew Lanman, Adam La Plante, Paul Liu, Adrian Ma, Yin-Zhe MacMahon, David H. E. Malan, Lourence Malgas, Cresshim Malgas, Keith Marero, Bradley Martinot, Zachary E. McBride, Lisa Mesinger, Andrei Mirocha, Jordan Mohamed-Hinds, Nicel Molewa, Mathakane Morales, Miguel F. Muñoz, Julian B. Murray, Steven G. Nikolic, Bojan Nuwegeld, Hans Parsons, Aaron R. Pascua, Robert Patra, Nipanjana Pochinda, Simon Qin, Yuxiang Rath, Eleanor Razavi-Ghods, Nima Riley, Daniel Rosie, Kathryn Santos, Mario G. Singh, Saurabh Storer, Dara Swarts, Hilton Tan, Jianrong Thélie, Emilie van Wyngaarden, Pieter Wilensky, Michael J. Williams, Peter K. G. Zheng, Haoxuan |
| contents | We report the first upper limits on the power spectrum of 21-cm fluctuations during the Epoch of Reionization and Cosmic Dawn from Phase II of the Hydrogen Epoch of Reionization Array (HERA) experiment. HERA Phase II constitutes several significant improvements in the signal chain compared to Phase I, most notably resulting in expanded frequency bandwidth, from 50-250 MHz. In these first upper limits, we investigate a small two-week subset of the available Phase II observations, with a focus on identifying new systematic characteristics of the instrument, and establishing an analysis pipeline to account for them. We report 2$σ$ upper limits in eight spectral bands, spanning $5.6 \leq z \leq 24.4$ that are consistent with thermal noise at the $2σ$ level for $k \gtrsim 0.6-0.9 h{\rm Mpc}^{-1}$ (band dependent). Our tightest limit during Cosmic Dawn ($z>12$) is $1.13\times 10^6 {\rm mK}^2$ at ($k=0.55 h{\rm Mpc}^{-1}, z=16.78$), and during the EoR ($5.5<z<12$) it is $1.78\times 10^3 {\rm mK}^2$ at ($k=0.70 h{\rm Mpc}^{-1}, z=7.05$). We find that mutual coupling has become our dominant systematic, leaking foreground power that strongly contaminates the low-$k$ modes, resulting in the loss of modes from $k=0.35-0.55$ compared to Phase I data. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_21289 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | First Results from HERA Phase II The HERA Collaboration Abdurashidova, Zuhra Adams, Tyrone Aguirre, James E. Baartman, Rushelle Barkana, Rennan Berkhout, Lindsay M. Bernardi, Gianni Billings, Tashalee S. Bizarria, Bruno B. Bowman, Judd D. Breitman, Daniela Bull, Philip Burba, Jacob Byrne, Ruby Carey, Steven Chandra, Rajorshi Sushovan Chen, Kai-Feng Choudhuri, Samir Cox, Tyler DeBoer, David R. Acedo, Eloy de Lera Dexter, Matt Dhandha, Jiten Dillon, Joshua S. Dynes, Scott Eksteen, Nico Ely, John Ewall-Wice, Aaron Fagnoni, Nicolas Fialkov, Anastasia Furlanetto, Steven R. Gale-Sides, Kingsley Garsden, Hugh Gorce, Adelie Gorthi, Deepthi Halday, Ziyaad Hazelton, Bryna J. Hewitt, Jacqueline N. Hickish, Jack Huang, Tian Jacobs, Daniel C. Josaitis, Alec Kern, Nicholas S. Kerrigan, Joshua Kittiwisit, Piyanat Kolopanis, Matthew Lanman, Adam La Plante, Paul Liu, Adrian Ma, Yin-Zhe MacMahon, David H. E. Malan, Lourence Malgas, Cresshim Malgas, Keith Marero, Bradley Martinot, Zachary E. McBride, Lisa Mesinger, Andrei Mirocha, Jordan Mohamed-Hinds, Nicel Molewa, Mathakane Morales, Miguel F. Muñoz, Julian B. Murray, Steven G. Nikolic, Bojan Nuwegeld, Hans Parsons, Aaron R. Pascua, Robert Patra, Nipanjana Pochinda, Simon Qin, Yuxiang Rath, Eleanor Razavi-Ghods, Nima Riley, Daniel Rosie, Kathryn Santos, Mario G. Singh, Saurabh Storer, Dara Swarts, Hilton Tan, Jianrong Thélie, Emilie van Wyngaarden, Pieter Wilensky, Michael J. Williams, Peter K. G. Zheng, Haoxuan Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies We report the first upper limits on the power spectrum of 21-cm fluctuations during the Epoch of Reionization and Cosmic Dawn from Phase II of the Hydrogen Epoch of Reionization Array (HERA) experiment. HERA Phase II constitutes several significant improvements in the signal chain compared to Phase I, most notably resulting in expanded frequency bandwidth, from 50-250 MHz. In these first upper limits, we investigate a small two-week subset of the available Phase II observations, with a focus on identifying new systematic characteristics of the instrument, and establishing an analysis pipeline to account for them. We report 2$σ$ upper limits in eight spectral bands, spanning $5.6 \leq z \leq 24.4$ that are consistent with thermal noise at the $2σ$ level for $k \gtrsim 0.6-0.9 h{\rm Mpc}^{-1}$ (band dependent). Our tightest limit during Cosmic Dawn ($z>12$) is $1.13\times 10^6 {\rm mK}^2$ at ($k=0.55 h{\rm Mpc}^{-1}, z=16.78$), and during the EoR ($5.5<z<12$) it is $1.78\times 10^3 {\rm mK}^2$ at ($k=0.70 h{\rm Mpc}^{-1}, z=7.05$). We find that mutual coupling has become our dominant systematic, leaking foreground power that strongly contaminates the low-$k$ modes, resulting in the loss of modes from $k=0.35-0.55$ compared to Phase I data. |
| title | First Results from HERA Phase II |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2511.21289 |