Krolewski, Alex;
Percival, Will J;
Ferraro, Simone;
Chaussidon, Edmond;
Rezaie, Mehdi;
Aguilar, Jessica N;
Ahlen, Steven;
... Zhou, Zhimin; + view all
(2024)
Constraining primordial non-Gaussianity from DESI quasar targets and Planck CMB lensing.
Journal of Cosmology and Astroparticle Physics
, 2024
(3)
, Article 021. 10.1088/1475-7516/2024/03/021.
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Abstract
We detect the cross-correlation between 2.7 million DESI quasar targets across 14,700 deg² (180 quasars deg⁻²) and Planck 2018 CMB lensing at ∼30σ. We use the cross-correlation on very large scales to constrain local primordial non-Gaussianity via the scale dependence of quasar bias. The DESI quasar targets lie at an effective redshift of 1.51 and are separated into four imaging regions of varying depth and image quality. We select quasar targets from Legacy Survey DR9 imaging, apply additional flux and photometric redshift cuts to improve the purity and reduce the fraction of unclassified redshifts, and use early DESI spectroscopy of 194,000 quasar targets to determine their redshift distribution and stellar contamination fraction (2.6%). Due to significant excess large-scale power in the quasar autocorrelation, we apply weights to mitigate contamination from imaging systematics such as depth, extinction, and stellar density. We use realistic contaminated mocks to determine the greatest number of systematic modes that we can fit, before we are biased by overfitting and spuriously remove real power. We find that linear regression with one to seven imaging templates removed per region accurately recovers the input cross-power, fNL and linear bias. As in previous analyses, our fNL constraint depends on the linear primordial non-Gaussianity bias parameter, bϕ = 2(b - p)δ꜀ assuming universality of the halo mass function. We measure fNL = -26⁺⁴⁵₋₄₀ with p = 1.6 (fNL = -18²⁹₋₂₇ with p = 1.0), and find that this result is robust under several systematics tests. Future spectroscopic quasar cross-correlations with Planck lensing can tighten the fNL constraints by a factor of 2 if they can remove the excess power on large scales in the quasar auto power spectrum.
| Type: | Article |
|---|---|
| Title: | Constraining primordial non-Gaussianity from DESI quasar targets and Planck CMB lensing |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/1475-7516/2024/03/021 |
| Publisher version: | http://dx.doi.org/10.1088/1475-7516/2024/03/021 |
| Language: | English |
| Additional information: | © 2024 The Author(s). Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10190278 |
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