arXiv subjects

Vivian I. Sabla

Publications and source records attributed to Vivian I. Sabla.

3 recordsLinked to original sources

arXiv2024

Unlocking New Physics with Joint Power Spectrum and Voxel Intensity Distribution Forecasts in Line-Intensity Mapping

The power spectrum and voxel intensity distribution (VID) are two summary statistics that can be applied to condense the information encoded in line-intensity maps. The information contained in both summary statistics is highly complementary, and their combination allows for a major increase in precision of parameter estimation from line-intensity mapping (LIM) surveys. Until recently, combination of these statistics required simulation-based estimations of their covariance. In this work we leverage an analytical model of covariance between these observables to run a joint Fisher forecast focusing on the CO(1-0) rotational line targeted by the COMAP survey and a wider, shallower hypothetical iteration. We consider a generalized phenomenological non-CDM model, models with axion dark matter, and local primordial non-Gaussianity, to highlight where a combined analysis of the power spectrum and VID can be most useful. Our results demonstrate improvements in sensitivity to beyond-$Λ$CDM physics over analyses using either the power spectrum or VID on their own, by factors ranging from 2 to 50, showcasing the potential of joint analyses in unlocking new insights into fundamental physics with LIM surveys.

astro-ph.CO↗

arXiv2022

Microphysics of Early Dark Energy

Early Dark Energy (EDE) relies on scalar field dynamics to resolve the Hubble tension, by boosting the pre-recombination length scales and thereby raising the CMB-inferred value of the Hubble constant into agreement with late universe probes. However, the collateral effect of scalar field microphysics on the linear perturbation spectra appears to preclude a fully satisfactory solution. $H_0$ is not raised without the inclusion of a late universe prior, and the "$S_8$-tension", a discrepancy between early- and late-universe measurements of the structure growth parameter, is exacerbated. What if EDE is not a scalar field? Here, we investigate whether different microphysics, encoded in the constitutive relationships between pressure and energy density fluctuations, can relieve these tensions. We show that EDE with an anisotropic sound speed can soften both the $H_0$ and $S_8$ tensions while still providing a quality fit to CMB data. Future observations from the CMB-S4 experiment may be able to distinguish the underlying microphysics at the $4σ$ level, and thereby test whether a scalar field or some richer physics is at work.

astro-ph.CO↗

arXiv2021

No H_0 Assistance from Assisted Quintessence

Early dark energy, as a proposed solution to the Hubble tension, faces an additional "why now" problem. Why should dark energy emerge just prior to recombination, billions of years before the onset of cosmic acceleration? Assisted quintessence explains this connection by positing that multiple scaling fields build up over time to drive the present-day cosmic acceleration. In this framework, early dark energy is inevitable. Yet, we show that scaling also leads to the demise of the scenario: the same feature that solves the coincidence problem then spoils a concordance of the Hubble constant inferred from the cosmic microwave background with that from the local distance ladder. The failure of the model offers a novel lesson on the ability of new physics to resolve the Hubble tension.

astro-ph.CO↗