Searcharxiv⌕ Search

arXiv subjects

Nicholas DePorzio

Publications and source records attributed to Nicholas DePorzio.

5 recordsLinked to original sources
arXiv2026

Using SquiRels to Find LiMRs: A Model-Insensitive Approach to Cosmic Microwave Background Studies of Light but Massive Relics

Light but Massive Relics (LiMRs), cosmological relics that are relativistic at some point in the observable early universe but are non-relativistic today, are a generic prediction of many theories of physics beyond the Standard Model, and are a target of high interest for current and upcoming cosmological surveys. The enormous variety of scenarios that can give rise to LiMRs also gives rise to a wide range of possible phase space distributions for these relics, making it valuable to have a model-agnostic quantification of LiMR signatures. Toward that end we identify three independent physical quantities that govern LiMRs' dominant effects on cosmological observables, and introduce a phenomenological family of "Squished Relics" (SquiRels) that allow us to efficiently and flexibly search for the imprint of LiMRs with different phase space distributions in data. Our primary focus here is on LiMRs that transition from radiation to matter during the Cosmic Microwave Background epoch. Using this framework we explicitly demonstrate that current Planck observations are not sensitive to the shape of the LiMR's phase space distribution function, which allows us to provide a model-insensitive and readily reinterpretable limit on LiMRs that become non-relativistic at redshifts z_{NR}<10^5. We further demonstrate that upcoming and future ground-based observatories will be able to distinguish LiMRs from massless dark radiation species, and could begin to provide information about the shape of its distribution.

astro-ph.CO↗
arXiv2024

Mass Beyond Measure: Eccentric Searches for Black Hole Populations

Stellar mass binary black holes of unknown formation mechanism have been observed, motivating new methods for distinguishing distinct black hole populations. This work explores how the orbital eccentricity of stellar mass binary black holes is a viable conduit for making such distinctions. Four different production mechanisms, and their corresponding eccentricity distributions, are studied in the context of an experimental landscape composed of mHz (LISA), dHz (DECIGO), and Hz (LIGO) range gravitational wave detectors. We expand on prior work considering these effects at fixed population eccentricity. We show that a strong signal corresponding to subsets of eccentric populations is effectively hidden from the mHz and dHz range gravitational wave detectors without the incorporation of high eccentricity waveform templates. Even with sufficiently large eccentricity templates, we find dHz range experiments with a LISA-like level of sensitivity are unlikely to aid in distinguishing different populations. We consider the degree to which a mHz range detector like LISA can differentiate among black hole populations independently and in concert with follow-up merger detection for binaries coalescing within a 10 year period. We find that mHz range detectors, with only $e < 0.01$ (nearly circular) sensitivity, can successfully discern eccentric sub-populations except when attempting to distinguish very low eccentricity distributions. In these cases where $e < 0.01$ sensitivity is insufficient, we find that the increase in event counts resulting from $e < 0.1$ sensitivity provides a statistically significant signal for discerning even these low eccentricity sub-populations. While improvements offered by $e<0.1$ sensitivity can be generally increased by $\mathcal{O}(1)$ factors with $e<0.4$ sensitivity, going beyond this in eccentricity sensitivity provides negligible enhancement.

gr-qc↗
arXiv2021

Accurately Weighing Neutrinos with Cosmological Surveys

A promising avenue to measure the total, and potentially individual, mass of neutrinos consists of leveraging cosmological datasets, such as the cosmic microwave background and surveys of the large-scale structure of the universe. In order to obtain unbiased estimates of the neutrino mass, however, many effects ought to be included. Here we forecast, via a Markov Chain Monte Carlo likelihood analysis, whether measurements by two galaxy surveys: DESI and {\it Euclid}, when added to the CMB-S4 experiment, are sensitive to two effects that can alter neutrino-mass measurements. The first is the slight difference in the suppression of matter fluctuations that each neutrino-mass hierarchy generates, at fixed total mass. The second is the growth-induced scale-dependent bias (GISDB) of haloes produced by massive neutrinos. We find that near-future surveys can distinguish hierarchies with the same total mass only at the $1σ$ level; thus, while these are poised to deliver a measurement of the sum of neutrino masses, they cannot significantly discern the mass of each individual neutrino in the foreseeable future. We further find that neglecting the GISDB induces up to a $1σ$ overestimation of the total neutrino mass, and we show how to absorb this effect via a redshift-dependent parametrization of the scale-independent bias.

astro-ph.CO↗
arXiv2021

Finding eV-scale Light Relics with Cosmological Observables

Cosmological data provide a powerful tool in the search for physics beyond the Standard Model (SM). An interesting target are light relics, new degrees of freedom which decoupled from the SM while relativistic. Nearly massless relics contribute to the radiation energy budget, and are commonly parametrized as variations in the effective number $N_{\rm eff}$ of neutrino species. Additionally, relics with masses greater than $10^{-4}$ eV become non-relativistic before today, and thus behave as matter instead of radiation. This leaves an imprint in the clustering of the large-scale structure of the universe, as light relics have important streaming motions, mirroring the case of massive neutrinos. Here we forecast how well current and upcoming cosmological surveys can probe light massive relics (LiMRs). We consider minimal extensions to the SM by both fermionic and bosonic relic degrees of freedom. By combining current and upcoming cosmic-microwave-background and large-scale-structure surveys, we forecast the significance at which each LiMR, with different masses and temperatures, can be detected. We find that a very large coverage of parameter space will be attainable by upcoming experiments, opening the possibility of exploring uncharted territory for new physics beyond the SM.

astro-ph.CO↗