Journal: Journal of Cosmology and Astroparticle Physics

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IOP Publishing

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1475-7516

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Publications1 - 10 of 133
  • Reconstructing primordial curvature perturbations via scalar-induced gravitational waves with LISA
    Item type: Journal Article
    El Gammal, Jonas; Ghaleb, Aya; Franciolini, Gabriele; et al. (2025)
    Journal of Cosmology and Astroparticle Physics
    Many early universe scenarios predict an enhancement of scalar perturbations at scales currently unconstrained by cosmological probes. These perturbations source gravitational waves (GWs) at second order in perturbation theory, leading to a scalar-induced gravitational wave (SIGW) background. The LISA detector, sensitive to mHz GWs, will be able to constrain curvature perturbations in a new window corresponding to scales k ∈ [10$^{10}$, 10$^{14}$] Mpc$^{-1}$, difficult to probe otherwise. In this work, we forecast the capabilities of LISA to constrain the source of SIGWs using different approaches: i) agnostic, where the spectrum of curvature perturbations is binned in frequency space; ii) template-based, modeling the curvature power spectrum based on motivated classes of models; iii) ab initio, starting from first-principles model of inflation featuring an ultra-slow roll phase. We compare the strengths and weaknesses of each approach. We also discuss the impact on the SIGW spectrum of non-standard thermal histories affecting the kernels of SIGW emission and non-Gaussianity in the statistics of the curvature perturbations. Finally, we propose simple tests to assess whether the signal is compatible with the SIGW hypothesis. The pipeline used is built into the SIGWAY code.
  • The BOSS bispectrum analysis at one loop from the Effective Field Theory of Large-Scale Structure
    Item type: Journal Article
    D’Amico, Guido; Donath, Yaniv; Lewandowski, Matthew; et al. (2024)
    Journal of Cosmology and Astroparticle Physics
    We analyze the BOSS power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the Effective Field Theory of Large-Scale Structure (EFTofLSS). Specifically, we use the one loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. After validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. We find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. After fixing the spectral tilt to Planck preferred value and using a Big Bang Nucleosynthesis prior, we measure σ 8 = 0.794 ± 0.037, h = 0.692 ± 0.011, and Ωm = 0.311 ± 0.010 to about 4.7%, 1.6%, and 3.2%, at 68% CL, respectively. This represents an error bar reduction with respect to the power spectrum-only analysis of about 30%, 18%, and 13% respectively. Remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the EFTofLSS in simultaneously predicting several observables. We find no tension with Planck.
  • Dark matter line searches with the Cherenkov Telescope Array
    Item type: Journal Article
    The CTAO Consortium; Abe, Shotaro; Abhir, Jayant; et al. (2024)
    Journal of Cosmology and Astroparticle Physics
    Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g. box-shaped spectra, that would likewise very clearly point to a particle dark matter origin.
  • Oscillation effects on supernova neutrino rates and spectra and detection of the shock breakout in a liquid argon TPC
    Item type: Journal Article
    Gil-Botella, I.; Rubbia, A. (2003)
    Journal of Cosmology and Astroparticle Physics
  • Dark Energy, Dark Matter and baryogenesis from a model of a complex axion field
    Item type: Journal Article
    Brandenberger, Robert; Fröhlich, Jürg (2021)
    Journal of Cosmology and Astroparticle Physics
    We introduce and study a model designed to simultaneously shed light on the mysteries connected with Baryogenesis, Dark Matter and Dark Energy. The model describes a self-interacting complex axion field whose imaginary part, a pseudo-scalar axion, couples to the instanton density of gauge fields including the hypercharge field. This coupling may give rise to baryogenesis in the early universe. After tracing out the gauge and matter degrees of freedom, a non-trivial effective potential for the angular component of the axion field is obtained. It is proposed that oscillations of this component around a minimum of its effective potential can be interpreted as Dark Matter. The absolute value of the axion field rolls slowly towards 0. At late times, it can give rise to Dark Energy.
  • Fast forward modelling of galaxy spatial and statistical distributions
    Item type: Journal Article
    Berner, Pascale; Refregier, Alexandre; Moser, Beatrice; et al. (2024)
    Journal of Cosmology and Astroparticle Physics
    A forward modelling approach provides simple, fast and realistic simulations of galaxy surveys, without a complex underlying model. For this purpose, galaxy clustering needs to be simulated accurately, both for the usage of clustering as its own probe and to control systematics. We present a forward model to simulate galaxy surveys, where we extend the Ultra-Fast Image Generator to include galaxy clustering. We use the distribution functions of the galaxy properties, derived from a forward model adjusted to observations. This population model jointly describes the luminosity functions, sizes, ellipticities, SEDs and apparent magnitudes. To simulate the positions of galaxies, we then use a two-parameter relation between galaxies and halos with Subhalo Abundance Matching (SHAM). We simulate the halos and subhalos using the fast PINOCCHIO code, and a method to extract the surviving subhalos from the merger history. Our simulations contain a red and a blue galaxy population, for which we build a SHAM model based on star formation quenching. For central galaxies, mass quenching is controlled with the parameter Mlimit, with blue galaxies residing in smaller halos. For satellite galaxies, environmental quenching is implemented with the parameter tquench, where blue galaxies occupy only recently merged subhalos. We build and test our model by comparing to imaging data from the Dark Energy Survey Year 1. To ensure completeness in our simulations, we consider the brightest galaxies with i < 20. We find statistical agreement between our simulations and the data for two-point correlation functions on medium to large scales. Our model provides constraints on the two SHAM parameters Mlimit and tquench and offers great prospects for the quick generation of galaxy mock catalogues, optimized to agree with observations.
  • One-loop renormalization in Galileon effective field theory
    Item type: Journal Article
    Heisenberg, Lavinia; Steinwachs, Christian F. (2020)
    Journal of Cosmology and Astroparticle Physics
  • A lower bound on the mass of dark matter particles
    Item type: Journal Article
    Boyarsky, Alexey; Ruchayskiy, Oleg; Iakubovskyi, Dmytro (2009)
    Journal of Cosmology and Astroparticle Physics
  • A universal velocity distribution of relaxed collisionless structures
    Item type: Journal Article
    Hansen, Steen H.; Moore, Ben; Zemp, Marcel; et al. (2006)
    Journal of Cosmology and Astroparticle Physics
  • Towards a dark sector model from string theory
    Item type: Journal Article
    Bernardo, Heliudson; Brandenberger, Robert; Fröhlich, Jürg (2022)
    Journal of Cosmology and Astroparticle Physics
    An embedding of a unified dark sector model into string theory with the following features is proposed: the model-independent axion descending from the Kalb-Ramond 2-form field is identified with the dark-matter field, and the real part of a Kähler modulus field — the “radius” of one of the extra spatial dimensions — accounts for dark energy. The expectation value of the dilaton field is stabilized by a gaugino condensation mechanism. A dark-energy potential with an amplitude corresponding to a realistic low energy scale results from some gentle tuning of the stabilized expectation value of the dilaton. The resulting potential reproduces the one in a previous dark-sector model proposed by two of us. Challenges to obtain a sufficiently flat potential are discussed.
Publications1 - 10 of 133