BAO

Ok(z) from supernova reconstructions combined with DESI DR2, for three data sets, colour-coded by Deltachi2; right: the resulting likelihoods. — $\mathcal{O}_k(z)$ from supernova reconstructions combined with DESI DR2, for three data sets, colour-coded by $\Delta\chi^2$ ; right: the resulting likelihoods.

L’Univers est-il plat ? Un test avec DESI DR2

2026 · JCAP 08 (2026) 016

Model independent test of the FLRW metric and the curvature in light of DESI DR2

Millard, C.†, L'Huillier, B.*, Douspis, M.

We reconstruct distances and the Hubble rate from Pantheon+ and DES supernovae without assuming any dark energy model, and combine them with DESI DR2 baryon acoustic oscillations to test the FLRW metric and measure the spatial curvature. With Pantheon+ and DESI DR2 we find $\Omega_{k,0} = 0.045^{+0.045}_{-0.081}$ , consistent with flatness and with Planck 2018.

DOI · arXiv:2601.20293

Articles clés Courbure et FLRW Supernovae Ia BAO Lissage itératif Avec mes étudiants

The curvature diagnostic Ok on mocks from four fiducial models: it recovers Omegak,0 = 0.1 when the input is curved. — The curvature diagnostic $\mathcal{O}_k$ on mocks from four fiducial models: it recovers $\Omega_{k,0} = 0.1$ when the input is curved.

Des tests décisifs pour Rubin et DESI

2025 · JCAP 05 (2025) 030

Litmus tests of the flat ΛCDM model and model-independent measurement of $H_0 r_\mathrm{d}$ with LSST and DESI

L'Huillier, B., Mitra, A., Shafieloo, A., Keeley, R. E., Koo, H.

Reconstructing the expansion history from simulated LSST supernovae and combining it with simulated DESI 5-year BAO, we forecast constraints of up to ±4% on the curvature and ±0.1 on $c/(H_0 r_\mathrm{d})$ , without assuming any form of dark energy.

DOI · arXiv:2407.07847

Articles clés Courbure et FLRW Supernovae Ia BAO Lissage itératif Premier auteur

Joint reconstructions of the effective gravitational coupling, H(z) and fsigma8(z) for three fiducial cosmologies; dashed lines show the truth. — Joint reconstructions of the effective gravitational coupling, $H(z)$ and $f\sigma_8(z)$ for three fiducial cosmologies; dashed lines show the truth.

2022 · Phys. Rev. D 106 (2022) 083513

Joint reconstructions of growth and expansion histories from stage-IV surveys with minimal assumptions I: dark energy beyond $\Lambda$

Calderón, R., L'Huillier, B., Polarski, D., Shafieloo, A., Starobinsky, A. A.

Gaussian processes reconstruct the dark energy density from forecast stage-IV supernova, BAO and redshift-space-distortion data, assuming only a flat FLRW universe that becomes matter-dominated at high redshift, which also yields the growth history. Several dark energy models can be distinguished from ΛCDM at $2\sigma$ or more.

DOI · arXiv:2206.13820

Énergie noire Supernovae Ia BAO Croissance des structures (RSD)Processus gaussiens

Theta(z) (top) and Ok(z) (bottom) from supernovae and BOSS/eBOSS BAO. A flat FLRW universe gives Theta = 1. — $\Theta(z)$ (top) and $\mathcal{O}_k(z)$ (bottom) from supernovae and BOSS/eBOSS BAO. A flat FLRW universe gives $\Theta = 1$ .

2018 · Phys. Rev. D 98 (2018) 083526

Falsifying ΛCDM: model-independent tests of the concordance model with eBOSS DR14Q and Pantheon

Shafieloo, A., L'Huillier, B.*, Starobinsky, A. A.

Combining model-independent expansion reconstructions from Pantheon supernovae and BAO, we test the FLRW metric and flatness, and use eBOSS DR14Q growth data to constrain $\Omega_\mathrm{m}$ , $\gamma$ and $\sigma_8$ . Everything is consistent with a flat FLRW universe, General Relativity and $\Lambda$ , with some tension at $z > 1$ .

DOI · arXiv:1804.04320

Articles clés Courbure et FLRW Gravité modifiée Supernovae Ia BAO Croissance des structures (RSD)Lissage itératif

Theta(z) and the curvature diagnostic Ok(z) at the BOSS LOWZ and CMASS redshifts, one point per supernova-based reconstruction. A flat FLRW universe gives Theta = 1 and Ok = 0. — $\Theta(z)$ and the curvature diagnostic $\mathcal{O}_k(z)$ at the BOSS LOWZ and CMASS redshifts, one point per supernova-based reconstruction. A flat FLRW universe gives $\Theta = 1$ and $\mathcal{O}_k = 0$ .

Tester ΛCDM sans le supposer

2017 · JCAP 01 (2017) 015

Model-independent test of the FLRW metric, the flatness of the Universe, and non-local measurement of $H_0 r_\mathrm{d}$

L'Huillier, B., Shafieloo, A.

Combining BOSS DR12 BAO with JLA supernovae, we measure $H_0 r_\mathrm{d}$ without assuming a cosmological model and introduce the $\Theta(z)$ diagnostic of the flat-FLRW metric. The results are consistent with a flat FLRW universe within $2\sigma$ .

DOI · arXiv:1606.06832

Articles clés Courbure et FLRW Supernovae Ia BAO Lissage itératif Premier auteur

Publications

Model independent test of the FLRW metric and the curvature in light of DESI DR2

Litmus tests of the flat ΛCDM model and model-independent measurement of H0rdH_0 r_\mathrm{d}H0​rd​ with LSST and DESI

Joint reconstructions of growth and expansion histories from stage-IV surveys with minimal assumptions I: dark energy beyond Λ\LambdaΛ

Falsifying ΛCDM: model-independent tests of the concordance model with eBOSS DR14Q and Pantheon

Model-independent test of the FLRW metric, the flatness of the Universe, and non-local measurement of H0rdH_0 r_\mathrm{d}H0​rd​

Litmus tests of the flat ΛCDM model and model-independent measurement of $H_0 r_\mathrm{d}$ with LSST and DESI

Joint reconstructions of growth and expansion histories from stage-IV surveys with minimal assumptions I: dark energy beyond $\Lambda$

Model-independent test of the FLRW metric, the flatness of the Universe, and non-local measurement of $H_0 r_\mathrm{d}$