Putting Flat $Λ$CDM In The (Redshift) Bin
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| Format: | Preprint |
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2022
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| author | Colgáin, Eoin Ó Sheikh-Jabbari, M. M. Solomon, Rance Dainotti, Maria G. Stojkovic, Dejan |
| author_facet | Colgáin, Eoin Ó Sheikh-Jabbari, M. M. Solomon, Rance Dainotti, Maria G. Stojkovic, Dejan |
| contents | Flat $Λ$CDM cosmology is specified by two constant fitting parameters at the background level in the late Universe, the Hubble constant $H_0$ and matter density (today) $Ω_m$. Mathematically, $H_0$ and $Ω_m$ are either integration constants arising from solving ordinary differential equations or are directly related to integration constants. Seen in this context, if fits of the $Λ$CDM model to cosmological probes at different redshifts lead to different $(H_0, Ω_m)$ parameters, this is a mismatch between mathematics and observation. Here, in mock observational Hubble data (OHD) (geometric probes of expansion history) we demonstrate evolution in distributions of best fit parameters with effective redshift. As a result, considerably different $(H_0, Ω_m)$ best fits from Planck-$Λ$CDM cannot be precluded in high redshift bins. We explore if OHD, Type Ia supernovae and standardisable quasar samples exhibit redshift evolution of best fit $Λ$CDM parameters. In all samples, we confirm a decreasing $H_0$ and increasing $Ω_m$ trend with increasing bin redshift. Through comparison with mocks, we confirm that similar behaviour can arise randomly within the flat $Λ$CDM model with probabilities as low as $p = 0.0021$ ($3.1 \, σ$). We present complementary profile distribution analysis confirming the shifts in cosmological parameters in high redshift bins. In particular, we identify a redshift range where Planck $(H_0, Ω_m)$ values are disfavoured at $99.6 \%$ ($2.9 σ$) confidence level in a combination of OHD and supernovae data. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2206_11447 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Putting Flat $Λ$CDM In The (Redshift) Bin Colgáin, Eoin Ó Sheikh-Jabbari, M. M. Solomon, Rance Dainotti, Maria G. Stojkovic, Dejan Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory Flat $Λ$CDM cosmology is specified by two constant fitting parameters at the background level in the late Universe, the Hubble constant $H_0$ and matter density (today) $Ω_m$. Mathematically, $H_0$ and $Ω_m$ are either integration constants arising from solving ordinary differential equations or are directly related to integration constants. Seen in this context, if fits of the $Λ$CDM model to cosmological probes at different redshifts lead to different $(H_0, Ω_m)$ parameters, this is a mismatch between mathematics and observation. Here, in mock observational Hubble data (OHD) (geometric probes of expansion history) we demonstrate evolution in distributions of best fit parameters with effective redshift. As a result, considerably different $(H_0, Ω_m)$ best fits from Planck-$Λ$CDM cannot be precluded in high redshift bins. We explore if OHD, Type Ia supernovae and standardisable quasar samples exhibit redshift evolution of best fit $Λ$CDM parameters. In all samples, we confirm a decreasing $H_0$ and increasing $Ω_m$ trend with increasing bin redshift. Through comparison with mocks, we confirm that similar behaviour can arise randomly within the flat $Λ$CDM model with probabilities as low as $p = 0.0021$ ($3.1 \, σ$). We present complementary profile distribution analysis confirming the shifts in cosmological parameters in high redshift bins. In particular, we identify a redshift range where Planck $(H_0, Ω_m)$ values are disfavoured at $99.6 \%$ ($2.9 σ$) confidence level in a combination of OHD and supernovae data. |
| title | Putting Flat $Λ$CDM In The (Redshift) Bin |
| topic | Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2206.11447 |