Probing primordial non-Gaussianity by reconstructing the initial conditions
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arXiv
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| Auteurs principaux: | , , |
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866909743967109120 |
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| author | Chen, Xinyi Padmanabhan, Nikhil Eisenstein, Daniel J. |
| author_facet | Chen, Xinyi Padmanabhan, Nikhil Eisenstein, Daniel J. |
| contents | We propose to constrain the primordial (local-type) non-Gaussianity signal by first reconstructing the initial density field to remove the late time non-Gaussianities introduced by gravitational evolution. Our reconstruction algorithm combines perturbation theory on large scales with a convolutional neural network on small scales. We reconstruct the squared potential (that sources the non-Gaussian signal) out to $k=0.2\ h$/Mpc to an accuracy of 99.8%. We cross-correlate this squared potential field with the reconstructed density field and verify that this computationally inexpensive estimator has the same information content as the full matter bispectrum. As a proof of concept, our approach can yield up to a factor of three improvement in the $f_{\rm NL}$ constraints, although it does not yet include the complications of galaxy bias or imperfections in the reconstruction. These potential improvements make it a promising alternative to current approaches to constraining primordial non-Gaussianity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_00968 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Probing primordial non-Gaussianity by reconstructing the initial conditions Chen, Xinyi Padmanabhan, Nikhil Eisenstein, Daniel J. Cosmology and Nongalactic Astrophysics We propose to constrain the primordial (local-type) non-Gaussianity signal by first reconstructing the initial density field to remove the late time non-Gaussianities introduced by gravitational evolution. Our reconstruction algorithm combines perturbation theory on large scales with a convolutional neural network on small scales. We reconstruct the squared potential (that sources the non-Gaussian signal) out to $k=0.2\ h$/Mpc to an accuracy of 99.8%. We cross-correlate this squared potential field with the reconstructed density field and verify that this computationally inexpensive estimator has the same information content as the full matter bispectrum. As a proof of concept, our approach can yield up to a factor of three improvement in the $f_{\rm NL}$ constraints, although it does not yet include the complications of galaxy bias or imperfections in the reconstruction. These potential improvements make it a promising alternative to current approaches to constraining primordial non-Gaussianity. |
| title | Probing primordial non-Gaussianity by reconstructing the initial conditions |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2412.00968 |