arXiv subjects

Vivian Poulin

Publications and source records attributed to Vivian Poulin.

At least 55 records · Page 3Linked to original sources

arXiv2023

Current small-scale CMB constraints to axion-like early dark energy

The SPT-3G 2018 TT/TE/EE cosmic microwave background (CMB) data set (temperature and polarization) is used to place constraints on an axion-like model of early dark energy (EDE). These data do not favor axion-like EDE and place an upper limit on the maximum fraction of the total energy density $f_{\rm EDE}< 0.172$ (at the 95% confidence level, CL). This is in contrast with ACT DR4 which gives $f_{\rm EDE}=0.150^{+0.050}_{-0.078}$. When combining CMB measurements with measurements of the baryon acoustic oscillations and luminosity distance to Type Ia supernovae, we show that the tension with the S$H_0$ES measurement of the Hubble parameter goes up from 2.6$σ$ with Planck to 2.9$σ$ with Planck+SPT-3G 2018. The additional inclusion of ACT DR4 data leads to a reduction of the tension to $1.6σ$, but the discrepancy between ACT DR4 and Planck+SPT-3G 2018 casts some doubt on the statistical consistency of this joint analysis. The importance of improved measurements of the CMB at both intermediate and small scales (in particular the shape of the damping tail) as well as the interplay between temperature and polarization measurements in constraining EDE are discussed. Upcoming ground-based measurements of the CMB will play a crucial role in determining whether EDE remains a viable model to address the Hubble tension.

astro-ph.CO↗

arXiv2023

Early Dark Energy beyond slow-roll: implications for cosmic tensions

In this work, we explore the possibility that Early Dark Energy (EDE) is dynamical in nature and study its effect on cosmological observables. We introduce a parameterization of the equation of state allowing for an equation of state $w$ differing considerably from cosmological constant (cc, $w={-1}$) and vary both the initial $w_i$ as well final $w_f$ equation of state of the EDE fluid. This idea is motivated by the fact that in many models of EDE, the scalar field may have some kinetic energy when it starts to behave like EDE before the CMB decoupling. We find that the present data have a mild preference for non-cc early dark energy $( w_i= -0.78)$ using Planck+BAO+Pantheon+S$H_0$ES data sets, leading to $Δχ^2_{\rm min}$ improvement of -2.5 at the expense of one more parameter. However, $w_i$ is only weakly constrained, with $w_i < -0.56$ at $1σ$. We argue that allowing for $w_i\neq -1$ can play a role in decreasing the $σ_8$ parameter. Yet, in practice the decrease is only $\sim0.4σ$ and $σ_8$ is still larger than weak lensing measurements. We conclude that while promising, a dynamical EDE cannot resolve both $H_0$ and $σ_8$ tensions simultaneously.

astro-ph.CO↗

arXiv2023

Cosmological inference from the EFTofLSS: the eBOSS QSO full-shape analysis

We present cosmological results inferred from the effective-field theory (EFT) analysis of the full-shape of eBOSS quasars (QSO) power spectrum. We validate our analysis pipeline against simulations, and find overall good agreement between the analyses in Fourier and configuration space. Keeping the baryon abundance and the spectral tilt fixed, we reconstruct at $68\%$ CL the fractional matter abundance $Ω_m$, the reduced Hubble constant $h$, and the clustering amplitude $σ_8$, to respectively $Ω_m=0.327\pm 0.035$, $h=0.655\pm 0.034$, and $σ_8=0.880\pm 0.083$ from eBOSS QSO alone. These constraints are consistent at $\lesssim 1.8σ$ with the ones from Planck and from the EFT analysis of BOSS full-shape. Interestingly $S_8$ reconstructed from eBOSS QSO is slightly higher than that deduced from Planck and BOSS, although statistically consistent. In combination with the EFT likelihood of BOSS, supernovae from Pantheon, and BAO from lyman-$α$ and 6dF/MGS, constraints improve to $Ω_m = 0.2985\pm 0.0069$ and $h = 0.6803\pm 0.0075$, in agreement with Planck and with similar precision. We also explore one-parameter extensions to $Λ$CDM and find that results are consistent with flat $Λ$CDM at $\lesssim 1.3σ$. We obtain competitive constraints on the curvature density fraction $Ω_k=-0.039\pm 0.029$, the dark energy equation of state $w_0=-1.038\pm 0.041$, the effective number of relativistic species $N_{\rm eff}=3.44^{+0.44}_{-0.91}$ at $68\%$ CL, and the sum of neutrino masses $\sum m_ν<0.274e$V at $95\%$ CL, without Planck data. Including Planck data, contraints significantly improve thanks to the large lever arm in redshift between LSS and CMB measurements. In particular, we obtain the stringent constraint $\sum m_ν<0.093e$V, competitive with recent lyman-$α$ forest power spectrum bound.

astro-ph.CO↗

arXiv2023

Consistency of effective field theory analyses of the BOSS power spectrum

We assess the robustness of $Λ$CDM results from the full-shape analysis of BOSS power spectrum using the one-loop prediction of the Effective Field Theory of Large-Scale Structure (EFTofLSS). The public likelihoods PyBird and CLASS-PT lead to results in agreement only at the $1σ$ level, despite the fact that they are derived from the same BOSS dataset and theory model. We perform a thorough comparison of the various analyses choices made between the two pipelines, and identify that the differences come from the choice of prior on the EFT parameters, dubbed "West-coast" (WC) and "East-coast" (EC) prior, respectively associated to PyBird and CLASS-PT. In particular, because posteriors are non-Gaussian, projection effects from the marginalization over the EFT parameters shift the posterior mean of the cosmological parameters with respect to the best-fit up to $1σ$ in the WC prior and up to $2σ$ in the EC prior. We quantify that best-fit cosmological parameters extracted from BOSS given the two prior choices are consistent at $\sim 1σ$. The consistency improves to $\sim 0.5σ$ when doubling the prior widths. While this reveals that current EFT analyses are subject to prior effects, we show that cosmological results obtained in combination with CMB, or from forthcoming large-volume data, are less sensitive to those effects. In addition, we investigate differences between BOSS measurements. We find broad agreements across all pre-reconstructed measurements considered ($<0.6σ$), but the two available BOSS post-reconstructed measurements in Fourier space, once combined with the EFT full-shape analysis, lead to discrepant Hubble parameter $H_0$ at $\sim 0.9σ$. Given the various effects we discuss, we argue that the clustering amplitude $σ_8$ measured with BOSS is not in statistical tension with that inferred from Planck under $Λ$CDM.

astro-ph.CO↗

arXiv2023

What it takes to solve the Hubble tension through modifications of cosmological recombination

We construct data-driven solutions to the Hubble tension which are perturbative modifications to the fiducial $Λ$CDM cosmology, using the Fisher bias formalism. Taking as proof of principle the case of a time-varying electron mass and fine structure constant, and focusing first on Planck CMB data, we demonstrate that a modified recombination can solve the Hubble tension and lower $S_8$ to match weak lensing measurements. Once baryonic acoustic oscillation and uncalibrated supernovae data are included, however, it is not possible to fully solve the tension with perturbative modifications to recombination.

astro-ph.CO↗

arXiv2023

Updated constraints from the effective field theory analysis of BOSS power spectrum on Early Dark Energy

Analyses of the full shape of BOSS DR12 power spectrum using the one-loop prediction from the Effective Field Theory of Large-Scale Structure (EFTBOSS) have led to new constraints on extensions to the $Λ$CDM model, such as Early Dark Energy (EDE) which has been suggested as a resolution to the "Hubble tension". In this paper, we re-assess the constraining power of the EFTBOSS on EDE in light of a correction to the normalization of BOSS window functions. Overall we find that constraints from EFTBOSS on EDE are weakened, and represent a small change compared to constraints from Planck and the conventional BAO/$fσ_8$ measurements. The combination of Planck data with EFTBOSS provides a bound on the maximal fractional contribution of EDE $f_{\rm EDE}<0.083$ at 95% C.L. (compared to $<0.054$ with the incorrect normalization, and $<0.088$ without full-shape data) and the Hubble tension is reduced to $2.1σ$. However, the more extreme model favored by an analysis with just data from the Atacama Cosmology Telescope is disfavored by the EFTBOSS data. We also show that the updated Pantheon+ Type Ia supernova analysis can slightly increase the constraints on EDE. Yet, the inclusion of the SN1a magnitude calibration by SH0ES strongly increases the preference for EDE to above $5σ$, yielding $f_{\rm EDE}\sim 0.12^{+0.03}_{-0.02}$ around the redshift $z_c=4365^{+3000}_{-1100}$. Our results demonstrate that EFTBOSS data (alone or combined with Planck data) do not exclude the EDE resolution of the Hubble tension.

astro-ph.CO↗

arXiv2022

Early-Universe Model Building

Theoretical investigations into the evolution of the early universe are an essential part of particle physics that allow us to identify viable extensions to the Standard Model as well as motivated parameter space that can be probed by various experiments and observations. In this white paper, we review particle physics models of the early universe. First, we outline various models that explain two essential ingredients of the early universe (dark matter and baryon asymmetry) and those that seek to address current observational anomalies. We then discuss dynamics of the early universe in models of neutrino masses, axions, and several solutions to the electroweak hierarchy problem. Finally, we review solutions to naturalness problems of the Standard Model that employ cosmological dynamics.

hep-ph↗

arXiv2022

Assessing the robustness of sound horizon-free determinations of the Hubble constant

The Hubble tension can be addressed by modifying the sound horizon ($r_s$) before recombination, triggering interest in $r_s$-free early-universe estimates of the Hubble constant, $H_0$. Constraints on $H_0$ from an $r_s$-free analysis of the full shape BOSS galaxy power spectra within LCDM were recently reported and used to comment on the viability of physics beyond LCDM. Here we demonstrate that $r_s$-free analyses with current data depend on the model and the priors placed on the cosmological parameters, such that LCDM analyses cannot be used as evidence for or against new physics. We find that beyond-LCDM models which introduce additional energy density with significant pressure support, such as early dark energy (EDE) or additional neutrino energy density ($ΔN_{\rm eff}$), lead to larger values of $H_0$. On the other hand, models which only affect the time of recombination, such as a varying electron mass ($Δm_e$), produce $H_0$ constraints similar to LCDM. Using BOSS data, constraints from light element abundances, cosmic microwave background (CMB) lensing, a CMB-based prior on the scalar amplitude ($A_s$), spectral index ($n_s$), and $Ω_m$ from the Pantheon+ supernovae data set, we find that in LCDM, $H_0=64.9\pm 2.2$ km/s/Mpc; EDE, $H_0=68.7^{+3}_{-3.9}$; $ΔN_{\rm eff}$, $H_0=68.1^{+2.7}_{-3.8}$; $Δm_e$, $H_0=64.7^{+1.9}_{-2.3}$. Using a prior on $Ω_m$ from uncalibrated BAO and CMB measurements of the projected sound horizon, these values become in LCDM, $H_0=68.8^{+1.8}_{-2.1}$; EDE, $H_0=73.7^{+3.2}_{-3.9}$; $ΔN_{\rm eff}$, $H_0=72.6^{+2.8}_{-3.7}$; $Δm_e$, $H_0=68.8\pm 1.9$. With current data, none of the models are in significant tension with SH0ES, and consistency tests based on comparing $H_0$ posteriors with and without $r_s$ marginalization are inconclusive with respect to the viability of beyond LCDM models.

astro-ph.CO↗

arXiv2022

Hints of Early Dark Energy in Planck, SPT, and ACT data: new physics or systematics?

We investigate constraints on early dark energy (EDE) using ACT DR4, SPT-3G 2018, Planck polarization, and restricted Planck temperature data (at $\ell<650$), finding a $3.3σ$ preference ($Δχ^2=-16.2$ for 3 additional degrees of freedom) for EDE over $Λ$CDM. The EDE contributes a maximum fractional energy density of $f_{\rm EDE}(z_c)=0.163^{+0.047}_{-0.04}$ at a redshift $z_c=3357\pm200$ and leads to a CMB inferred value of the Hubble constant $H_0=74.2^{+1.9}_{-2.1}$ km/s/Mpc. We find that Planck and ACT DR4 data provide the majority of the improvement in $χ^2$, and that the inclusion of SPT-3G pulls the posterior of $f_{\rm EDE}(z_c)$ away from $Λ$CDM. This is the first time that a moderate preference for EDE has been reported for these three combined CMB data sets. We find that including measurements of supernovae luminosity distances and the baryon acoustic oscillation standard ruler only minimally affects the preference ($3.0σ$), while measurements that probe the clustering of matter at late times - the lensing potential power spectrum from Planck and $f σ_8$ from BOSS - decrease the significance of the preference to 2.6$σ$. Conversely, adding a prior on the $H_0$ value as reported by the SH0ES collaboration increases the preference to the $4-5σ$ level. In the absence of this prior, the inclusion of Planck TT data at $\ell>1300$ reduces the preference from $3.0σ$ to $2.3σ$ and the constraint on $f_{\rm EDE}(z_c)$ becomes compatible with $Λ$CDM at $1σ$. We explore whether systematic errors in the Planck polarization data may affect our conclusions and find that changing the TE polarization efficiencies significantly reduces the Planck preference for EDE. More work will be necessary to establish whether these hints for EDE within CMB data alone are the sole results of systematic errors or an opening to new physics.

astro-ph.CO↗

arXiv2022

Improved cosmological constraints on the neutrino mass and lifetime

We present cosmological constraints on the sum of neutrino masses as a function of the neutrino lifetime, in a framework in which neutrinos decay into dark radiation after becoming non-relativistic. We find that in this regime the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO) and (uncalibrated) luminosity distance to supernovae from the Pantheon catalog constrain the sum of neutrino masses $\sum m_ν$ to obey $\sum m_ν< 0.42$ eV at (95$\%$ C.L.). While the the bound has improved significantly as compared to the limits on the same scenario from Planck 2015, it still represents a significant relaxation of the constraints as compared to the stable neutrino case. We show that most of the improvement can be traced to the more precise measurements of low-$\ell$ polarization data in Planck 2018, which leads to tighter constraints on $τ_{\rm reio}$ (and thereby on $A_s$), breaking the degeneracy arising from the effect of (large) neutrino masses on the amplitude of the CMB power spectrum.

hep-ph↗

arXiv2022

Constraining decaying dark matter with BOSS data and the effective field theory of large-scale structures

We update cosmological constraints on two decaying dark matter models in light of BOSS-DR12 data analyzed under the Effective Field Theory of Large-Scale Structures (EFTofLSS) formalism, together with Planck, Pantheon and other BOSS measurements of the baryonic acoustic oscillation (BAO). In the first model, a fraction $f_{\rm dcdm}$ of cold dark matter (CDM) decays into dark radiation (DR) with a lifetime $τ$. In the second model (recently suggested as a potential resolution to the $S_8$ tension), all the CDM decays with a lifetime $τ$ into DR and a massive warm dark matter (WDM) particle, with a fraction $\varepsilon$ of the CDM rest mass energy transferred to the DR. Using numerical codes from the recent literature, we perform the first calculation of the mildly non-linear (matter and galaxy) power spectra with the EFTofLSS for these two models. In the case of DR products, we obtain the constraints $f_{\rm dcdm}\lesssim0.022$ (95\% C.L.) for lifetimes shorter than the age of the universe, and $τ/f_{\rm dcdm} \gtrsim 250$ Gyr in the long-lived regime assuming $f_{\rm dcdm}\to1$. We show that Planck data contributes the most to these constraints, with EFTofBOSS providing a marginal improvement over conventional BAO and redshift space distortions ($fσ_8$) data. In the case of DR and WDM decay products, we find that EFTofBOSS data significantly improves the constraints at 68\% C.L. on the CDM lifetime with a $S_8$ prior from KiDS-1000. We show that, in order to fit EFTofBOSS data while lowering $S_8$ to match KiDS-1000, the best-fit model has a longer lifetime $τ= 120$ Gyr, with a larger kick velocity $v_{\rm kick}/c \simeq \varepsilon \simeq 1.2\%$, than that without EFTofBOSS ($τ= 43$ Gyr, $\varepsilon =0.6\%$). We anticipate that future surveys will provide exquisite constraints on such models.

astro-ph.CO↗

arXiv2022

Implications of the $S_8$ tension for decaying dark matter with warm decay products

Recent weak lensing surveys have revealed that the direct measurement of the parameter combination $S_8\equivσ_8(Ω_m/0.3)^{0.5}$ -- where $σ_8$ is a measure of the amplitude of matter fluctuations on 8 $h^{-1}$Mpc scales -- is $\sim3σ$ discrepant with the value reconstructed from cosmic microwave background (CMB) data assuming the $Λ$CDM model. In this article, we show that it is possible to resolve the tension if dark matter (DM) decays with a lifetime of $Γ^{-1} \simeq 55 \ \text{Gyrs}$ into one massless and one massive product, and transfers a fraction $\varepsilon\simeq 0.7 \ \%$ of its rest mass energy to the massless component. The velocity-kick received by the massive daughter leads to a suppression of gravitational clustering below its free-streaming length, thereby reducing the $σ_8$ value as compared to that inferred from the standard $Λ$CDM model, in a similar fashion to massive neutrino and standard warm DM. Contrarily to the latter scenarios, the time-dependence of the power suppression and the free-streaming scale allows the 2-body decaying DM scenario to accommodate CMB, baryon acoustic oscillation, growth factor and un-calibrated supernova Ia data. We briefly discuss implications for DM model building, galactic small-scale structure problems and the recent Xenon-1T excess. Future experiments measuring the growth factor to high accuracy at $0\lesssim z\lesssim1$ can further test this scenario.

astro-ph.CO↗

arXiv2022

Non-thermal neutrino-like hot dark matter in light of the $S_8$ tension

The $Λ$CDM prediction of $S_8\equivσ_8(Ω_m/0.3)^{0.5}$ -- where $σ_8$ is the root mean square of matter fluctuations on a 8 $h^{-1}$Mpc scale -- once calibrated on Planck CMB data is $2-3σ$ lower than its direct estimate by a number of weak lensing surveys. In this paper, we explore the possibility that the '$S_8$-tension' is due to a non-thermal hot dark matter (HDM) fractional contribution to the universe energy density leading to a power suppression at small-scales in the matter power spectrum. Any HDM models can be characterized by its effective mass $ m_{sp}^{\rm eff}$ and its contribution to the relativistic degrees of freedom at CMB decoupling $ΔN_{\rm eff}$. Taking the specific example of a sterile particle produced from the decay of the inflaton during a matter dominated era, we find that from Planck only the tension can be reduced below $2σ$, but Planck does not favor a non-zero ${m_{sp}^{\rm eff},ΔN_{\rm eff}}$. In combination with a measurement of $S_8$ from KIDS1000+BOSS+2dfLenS, the $S_8$-tension would hint at the existence of a particle of mass $ m_{sp}^{\rm eff} \simeq 0.67_{-0.48}^{+0.26}$ ${\rm eV}$ with a contribution to $ΔN_{\rm eff} \simeq0.06\pm0.05$. However, Pantheon and BOSS BAO/$fσ_8$ data restricts the particle mass to $m_{sp}^{\rm eff} \simeq 0.48_{-0.36}^{+0.17}$ and contribution to $ΔN_{\rm eff} \simeq 0.046_{-0.031}^{+0.004}$. We discuss implications of our results for other canonical non-thermal HDM models -- the Dodelson-Widrow model and a thermal sterile particle with a different temperature in the hidden sector. We report competitive results on such hidden sector temperature which might have interesting implications for particle physics model building, in particular connecting the $S_8$-tension to the longstanding short baseline oscillation anomaly.

astro-ph.CO↗

arXiv2022

Linear cosmological constraints on 2-body decaying dark matter scenarios and the $S_8$ tension

The '$S_8$ tension' is a longstanding discrepancy between the cosmic microwave background (CMB) and weak gravitational lensing determination of the amplitude of matter fluctuations, parametrized as $S_8\equivσ_8(Ω_m/0.3)^{0.5}$, where $σ_8$ is the root mean square of matter fluctuations on a 8 $h^{-1}$Mpc scale, and $Ω_m$ is the total matter abundance. It was recently shown that dark matter (DM) decaying into a massless (dark radiation) and a massive (warm DM) species, with a lifetime $Γ^{-1} \simeq 55~(\varepsilon/0.007)^{1.4}$ Gyrs -- where $\varepsilon$ represent the mass-energy fraction transferred to the massless component -- can ease the tension. Thanks to a fast and accurate fluid approximation scheme for the warm species, we perform a comprehensive study of this 2-body decaying DM scenario, discussing in detail its dynamics and its impact on the CMB and linear matter power spectra. We then investigate the implications for the '$S_8$ tension' against a number of changes in the analysis: different $S_8$ priors, marginalization over the lensing information in Planck data, trading Planck high$-\ell$ polarization data for those from the SPTpol and ACTPol surveys, and the inclusion of the recent results from the Xenon1T collaboration. We conclude that the preference for decaying DM, apparent only when the $S_8$ value determined from weak lensing data is added to the analysis, does not sensibly degrade the fit to any of the cosmological data-sets considered, and that the model could potentially explain the anomalous electron recoil excess reported by the Xenon1T collaboration. Furthermore, we explictly show that while current CMB data alone are not sensitive enough to distinguish between standard CDM and decaying DM, next-generation CMB observations (CMB-S4) can unambiguously detect its signature.

astro-ph.CO↗

arXiv2021

The $H_0$ Olympics: A fair ranking of proposed models

Despite the remarkable success of the $Λ$Cold Dark Matter ($Λ$CDM) cosmological model, a growing discrepancy has emerged (currently measured at the level of $\sim 4-6 σ$) between the value of the Hubble constant $H_0$ measured using the local distance ladder and the value inferred using the cosmic microwave background and galaxy surveys. While a vast array of $Λ$CDM extensions have been proposed to explain these discordant observations, understanding the (relative) success of these models in resolving the tension has proven difficult -- this is a direct consequence of the fact that each model has been subjected to differing, and typically incomplete, compilations of cosmological data. In this review, we attempt to make a systematic comparison of sixteen different models which have been proposed to resolve the $H_0$ tension (spanning both early- and late-Universe solutions), and quantify the relative success of each using a series of metrics and a vast array of data combinations. Owing to the timely appearance of this article, we refer to this contest as the ''$H_0$ Olympics''; the goal being to identify which of the proposed solutions, and more broadly which underlying mechanisms, are most likely to be responsible for explaining the observed discrepancy (should unaccounted for systematics not be the culprit). This work also establishes a foundation of tests which will allow the success of novel proposals to be meaningful ''benchmarked''.

astro-ph.CO↗

arXiv2021

Dark Energy at early times and ACT: a larger Hubble constant without late-time priors

In this paper we fit two models of Early Dark Energy (EDE) (an increase in the expansion rate before recombination) to the combination of Atacama Cosmology Telescope (ACT) measurements of the Cosmic Microwave Background (CMB) with data from either the WMAP or the Planck satellite, along with measurements of the baryon acoustic oscillations and uncalibrated supernovae luminosity distance. We study a phenomenological axion-like potential ('axEDE') and a scalar field experiencing a first-order phase-transition ('NEDE'). We find that for both models the 'Planck-free' analysis yields non-zero EDE at > 2 sigma and an increased value for $H_0 \sim 70-74$ km/s/Mpc, compatible with local measurements, without the inclusion of any prior on $H_0$. On the other hand, the inclusion of Planck data restricts the EDE contribution to an upper-limit only at 95% C.L. For axEDE, the combination of Planck and ACT leads to constraints 30% weaker than with Planck alone, and there is no residual Hubble tension. On the other hand, NEDE is more strongly constrained in a Planck+ACT analysis, and the Hubble tension remains at $\sim 3σ$, illustrating the ability for CMB data to distinguish between EDE models. We explore the apparent inconsistency between the Planck and ACT data and find that it comes (mostly) from a slight tension between the temperature power spectrum at multipoles around $\sim 1000$ and $\sim 1500$. Finally, through a mock analysis of ACT data, we demonstrate that the preference for EDE is not driven by a lack of information at high-$\ell$ when removing Planck data, and that a LCDM fit to the fiducial EDE cosmology results in a significant bias on $\{H_0,ω_{\rm cdm}\}$. More accurate measurements of the TT power spectra above $\ell\sim 2500$ and EE between $\ell \sim 300-500$ will play a crucial role in differentiating EDE models.

astro-ph.CO↗

arXiv2021

Early dark energy resolution to the Hubble tension in light of weak lensing surveys and lensing anomalies

Early Dark Energy (EDE) contributing a fraction $f_{\rm EDE}(z_c)\sim 10 \%$ of the energy density of the universe around $z_c\simeq 3500$ and diluting as or faster than radiation afterwards, can provide a resolution to the Hubble tension, the $\sim 5σ$ discrepancy between the $H_0$ value derived from early- and late-universe observations within $Λ$CDM. However, it has been pointed out that Large-Scale Structure (LSS) data, which are in $\sim3σ$ tension with $Λ$CDM and EDE cosmologies, might alter these conclusions. We reassess the viability of the EDE against a host of high- and low-redshift measurements, by combining LSS observations from recent weak lensing (WL) surveys with CMB, Baryon Acoustic Oscillation (BAO), growth function (FS) and Supernova Ia (SNIa) data. Introducing a model whose only parameter is $f_{\rm EDE}(z_c)$, we report a $\sim 2σ$ preference for non-zero $f_{\rm EDE}(z_c)$ from Planck data alone and the tension with SH0ES is reduced below $2σ$. Adding BAO, FS and SNIa does not affect this result, while the inclusion of a prior on $H_0$ from SH0ES increase the preference for non-zero EDE to $\sim3.6σ$. After checking the EDE non-linear matter power spectrum predicted by standard semi-analytical algorithms via a set of $N$-body simulations, we show that current WL data do not rule out EDE. We also caution against the interpretation of constraints obtained from combining statistically inconsistent data sets within the $Λ$CDM cosmology. In light of the CMB lensing anomalies, we show that the lensing-marginalized CMB data also favor non-zero $f_{\rm EDE}(z_c)$ at $\sim2σ$, predicts $H_0$ in $1.4σ$ agreement with SH0ES and $S_8$ in $1.5σ$ ($0.8σ$) agreement with KV (DES) data. Alternatively, we discuss promising extensions of the EDE cosmology that could allow to fully restore cosmological concordance.

astro-ph.CO↗

arXiv2021

The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. In this paper, we review various possible causes and consequences of deviations from radiation domination in the early Universe - taking place either before or after BBN - and the constraints on them, as they have been discussed in the literature during the recent years.

astro-ph.CO↗