Radio-optical synergies at high redshift to constrain primordial non-Gaussianity
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| Format: | Preprint |
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2023
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| _version_ | 1866913245022912512 |
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| author | Squarotti, Matilde Barberi Camera, Stefano Maartens, Roy |
| author_facet | Squarotti, Matilde Barberi Camera, Stefano Maartens, Roy |
| contents | We apply the multi-tracer technique to test the possibility of improved constraints on the amplitude of local primordial non-Gaussianity, $f_{\mathrm{NL}}$, in the cosmic large-scale structure. A precise measurement of $f_{\mathrm{NL}}$ is difficult because the effects of non-Gaussianity mostly arise on the largest scales, which are heavily affected by the low statistical sampling commonly referred to as cosmic variance. The multi-tracer approach suppresses cosmic variance and we implement it by combining the information from next-generation galaxy surveys in the optical/near-infrared band and neutral hydrogen (HI) intensity mapping surveys in the radio band. High-redshift surveys enhance the precision on $f_{\mathrm{NL}}$, due to the larger available volume, and HI intensity mapping surveys can naturally reach high redshifts. In order to extend the redshift coverage of a galaxy survey, we consider different emission-line galaxy populations, focusing on the H$α$ line at low redshift and on oxygen lines at higher redshift. By doing so, we cover a wide redshift range $1 \lesssim z \lesssim 4$. To assess the capability of our approach, we implement a synthetic-data analysis by means of Markov chain Monte Carlo sampling of the (cosmological+nuisance) parameter posterior, to evaluate the constraints on $f_{\mathrm{NL}}$ obtained in different survey configurations. We find significant improvements from the multi-tracer technique: the full data set leads to a precision of $σ(f_{\mathrm{NL}}) < 1$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2307_00058 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Radio-optical synergies at high redshift to constrain primordial non-Gaussianity Squarotti, Matilde Barberi Camera, Stefano Maartens, Roy Cosmology and Nongalactic Astrophysics We apply the multi-tracer technique to test the possibility of improved constraints on the amplitude of local primordial non-Gaussianity, $f_{\mathrm{NL}}$, in the cosmic large-scale structure. A precise measurement of $f_{\mathrm{NL}}$ is difficult because the effects of non-Gaussianity mostly arise on the largest scales, which are heavily affected by the low statistical sampling commonly referred to as cosmic variance. The multi-tracer approach suppresses cosmic variance and we implement it by combining the information from next-generation galaxy surveys in the optical/near-infrared band and neutral hydrogen (HI) intensity mapping surveys in the radio band. High-redshift surveys enhance the precision on $f_{\mathrm{NL}}$, due to the larger available volume, and HI intensity mapping surveys can naturally reach high redshifts. In order to extend the redshift coverage of a galaxy survey, we consider different emission-line galaxy populations, focusing on the H$α$ line at low redshift and on oxygen lines at higher redshift. By doing so, we cover a wide redshift range $1 \lesssim z \lesssim 4$. To assess the capability of our approach, we implement a synthetic-data analysis by means of Markov chain Monte Carlo sampling of the (cosmological+nuisance) parameter posterior, to evaluate the constraints on $f_{\mathrm{NL}}$ obtained in different survey configurations. We find significant improvements from the multi-tracer technique: the full data set leads to a precision of $σ(f_{\mathrm{NL}}) < 1$. |
| title | Radio-optical synergies at high redshift to constrain primordial non-Gaussianity |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2307.00058 |