Could Sample Variance be Responsible for the Parity-Violating Signal Seen in the BOSS Galaxy Survey?
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arXiv
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| Natura: | Preprint |
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2024
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| _version_ | 1866911759799943168 |
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| author | Philcox, Oliver H. E. Ereza, Julia |
| author_facet | Philcox, Oliver H. E. Ereza, Julia |
| contents | Recent works have uncovered an excess signal in the parity-odd four-point correlation function measured from the BOSS spectroscopic galaxy survey. If physical in origin, this could indicate evidence for new parity-breaking processes in the scalar sector, most likely from inflation. At heart, these studies compare the observed four-point correlator to the distribution obtained from parity-conserving mock galaxy surveys; if the simulations underestimate the covariance of the data, noise fluctuations may be misinterpreted as a signal. To test this, we reanalyse the BOSS CMASS + LOWZ parity-odd dataset with the noise distribution modeled using the newly developed GLAM-Uchuu suite of mocks. These comprise full N-body simulations that follow the evolution of $2000^3$ dark matter particles in a $Λ$CDM universe, and represent a significant upgrade compared to the formerly MultiDark-Patchy mocks, which were based on an alternative (non N-body) gravity solver. We find no significant evidence for parity-violation in the BOSS dataset (with a baseline detection significance of $1.4σ$), suggesting that the former signal ($>3.5σ$ with our data cuts) could be caused by an underestimation of the covariance in MultiDark-Patchy. The significant differences between results obtained with the two sets of BOSS-calibrated galaxy catalogs showcases the heightened sensitivity of beyond-two-point analyses to the treatment of non-linear effects and indicates that previous constraints may suffer from large systematic uncertainties. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_09523 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Could Sample Variance be Responsible for the Parity-Violating Signal Seen in the BOSS Galaxy Survey? Philcox, Oliver H. E. Ereza, Julia Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory Recent works have uncovered an excess signal in the parity-odd four-point correlation function measured from the BOSS spectroscopic galaxy survey. If physical in origin, this could indicate evidence for new parity-breaking processes in the scalar sector, most likely from inflation. At heart, these studies compare the observed four-point correlator to the distribution obtained from parity-conserving mock galaxy surveys; if the simulations underestimate the covariance of the data, noise fluctuations may be misinterpreted as a signal. To test this, we reanalyse the BOSS CMASS + LOWZ parity-odd dataset with the noise distribution modeled using the newly developed GLAM-Uchuu suite of mocks. These comprise full N-body simulations that follow the evolution of $2000^3$ dark matter particles in a $Λ$CDM universe, and represent a significant upgrade compared to the formerly MultiDark-Patchy mocks, which were based on an alternative (non N-body) gravity solver. We find no significant evidence for parity-violation in the BOSS dataset (with a baseline detection significance of $1.4σ$), suggesting that the former signal ($>3.5σ$ with our data cuts) could be caused by an underestimation of the covariance in MultiDark-Patchy. The significant differences between results obtained with the two sets of BOSS-calibrated galaxy catalogs showcases the heightened sensitivity of beyond-two-point analyses to the treatment of non-linear effects and indicates that previous constraints may suffer from large systematic uncertainties. |
| title | Could Sample Variance be Responsible for the Parity-Violating Signal Seen in the BOSS Galaxy Survey? |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2401.09523 |