The Atacama Cosmology Telescope: Reionization kSZ trispectrum methodology and limits

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Main Authors: MacCrann, Niall, Qu, Frank J., Namikawa, Toshiya, Bolliet, Boris, Cai, Hongbo, Calabrese, Erminia, Choi, Steve K., Darwish, Omar, Ferraro, Simone, Guan, Yilun, Hill, J. Colin, Hilton, Matt, Hložek, Renée, Kramer, Darby, Madhavacheril, Mathew S., Moodley, Kavilan, Sehgal, Neelima, Sherwin, Blake D., Sifón, Cristóbal, Staggs, Suzanne T., Trac, Hy, Van Engelen, Alexander, Vavagiakis, Eve M.
Format: Preprint
Published: 2024
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author MacCrann, Niall
Qu, Frank J.
Namikawa, Toshiya
Bolliet, Boris
Cai, Hongbo
Calabrese, Erminia
Choi, Steve K.
Darwish, Omar
Ferraro, Simone
Guan, Yilun
Hill, J. Colin
Hilton, Matt
Hložek, Renée
Kramer, Darby
Madhavacheril, Mathew S.
Moodley, Kavilan
Sehgal, Neelima
Sherwin, Blake D.
Sifón, Cristóbal
Staggs, Suzanne T.
Trac, Hy
Van Engelen, Alexander
Vavagiakis, Eve M.
author_facet MacCrann, Niall
Qu, Frank J.
Namikawa, Toshiya
Bolliet, Boris
Cai, Hongbo
Calabrese, Erminia
Choi, Steve K.
Darwish, Omar
Ferraro, Simone
Guan, Yilun
Hill, J. Colin
Hilton, Matt
Hložek, Renée
Kramer, Darby
Madhavacheril, Mathew S.
Moodley, Kavilan
Sehgal, Neelima
Sherwin, Blake D.
Sifón, Cristóbal
Staggs, Suzanne T.
Trac, Hy
Van Engelen, Alexander
Vavagiakis, Eve M.
contents Patchy reionization generates kinematic Sunyaev-Zeldovich (kSZ) anisotropies in the cosmic microwave background (CMB). Large-scale velocity perturbations along the line of sight modulate the small-scale kSZ power spectrum, leading to a trispectrum (or four-point function) in the CMB that depends on the physics of reionization. We investigate the challenges in detecting this trispectrum and use tools developed for CMB lensing, such as realization-dependent bias subtraction and cross-correlation based estimators, to counter uncertainties in the instrumental noise and assumed CMB power spectrum. We also find that both lensing and extragalactic foregrounds can impart larger trispectrum contributions than the reionization kSZ signal. We present a range of mitigation methods for both of these sources of contamination, validated on microwave-sky simulations. We use ACT DR6 and Planck data to calculate an upper limit on the reionization kSZ trispectrum from a measurement dominated by foregrounds. The upper limit is about 50 times the signal predicted from recent simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2405_01188
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Atacama Cosmology Telescope: Reionization kSZ trispectrum methodology and limits
MacCrann, Niall
Qu, Frank J.
Namikawa, Toshiya
Bolliet, Boris
Cai, Hongbo
Calabrese, Erminia
Choi, Steve K.
Darwish, Omar
Ferraro, Simone
Guan, Yilun
Hill, J. Colin
Hilton, Matt
Hložek, Renée
Kramer, Darby
Madhavacheril, Mathew S.
Moodley, Kavilan
Sehgal, Neelima
Sherwin, Blake D.
Sifón, Cristóbal
Staggs, Suzanne T.
Trac, Hy
Van Engelen, Alexander
Vavagiakis, Eve M.
Cosmology and Nongalactic Astrophysics
Patchy reionization generates kinematic Sunyaev-Zeldovich (kSZ) anisotropies in the cosmic microwave background (CMB). Large-scale velocity perturbations along the line of sight modulate the small-scale kSZ power spectrum, leading to a trispectrum (or four-point function) in the CMB that depends on the physics of reionization. We investigate the challenges in detecting this trispectrum and use tools developed for CMB lensing, such as realization-dependent bias subtraction and cross-correlation based estimators, to counter uncertainties in the instrumental noise and assumed CMB power spectrum. We also find that both lensing and extragalactic foregrounds can impart larger trispectrum contributions than the reionization kSZ signal. We present a range of mitigation methods for both of these sources of contamination, validated on microwave-sky simulations. We use ACT DR6 and Planck data to calculate an upper limit on the reionization kSZ trispectrum from a measurement dominated by foregrounds. The upper limit is about 50 times the signal predicted from recent simulations.
title The Atacama Cosmology Telescope: Reionization kSZ trispectrum methodology and limits
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2405.01188