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Babak, S.; Caprini, C.; Figueroa, D.G.; Karnesis, N.; Marcoccia, P.; Nardini, G.; Pieroni, M.; Ricciardone, A.; Sesana, A.; Torrado, J. |
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Title |
Stochastic gravitational wave background from stellar origin binary black holes in LISA |
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Journal Article |
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Year |
2023 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
08 |
Issue |
8 |
Pages |
034 - 37pp |
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Abstract |
We use the latest constraints on the population of stellar origin binary black holes (SOBBH) from LIGO/Virgo/KAGRA (LVK) observations, to estimate the stochastic gravitational wave background (SGWB) they generate in the frequency band of LISA. In order to account for the faint and distant binaries, which contribute the most to the SGWB, we extend the merger rate at high redshift assuming that it tracks the star formation rate. We adopt different methods to compute the SGWB signal: we perform an analytical evaluation, we use Monte Carlo sums over the SOBBH population realisations, and we account for the role of the detector by simulating LISA data and iteratively removing the resolvable signals until only the confusion noise is left. The last method allows the extraction of both the expected SGWB and the number of resolvable SOBBHs. Since the latter are few for signal-to-noise ratio thresholds larger than five, we confirm that the spectral shape of the SGWB in the LISA band agrees with the analytical prediction of a single power law. We infer the probability distribution of the SGWB amplitude from the LVK GWTC-3 posterior of the binary population model: at the reference frequency of 0.003 Hz it has an interquartile range of h2ΩGW(f = 3 × 10-3 Hz) ∈ [5.65, 11.5] × 10-13, in agreement with most previous estimates. We then perform a MC analysis to assess LISA's capability to detect and characterise this signal. Accounting for both the instrumental noise and the galactic binaries foreground, with four years of data, LISA will be able to detect the SOBBH SGWB with percent accuracy, narrowing down the uncertainty on the amplitude by one order of magnitude with respect to the range of possible amplitudes inferred from the population model. A measurement of this signal by LISA will help to break the degeneracy among some of the population parameters, and provide interesting constraints, in particular on the redshift evolution of the SOBBH merger rate. |
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no |
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yes |
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yes |
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IFIC @ pastor @ |
Serial |
6081 |
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Author |
Figueroa, D.G.; Florio, A.; Torrenti, F.; Valkenburg, W. |
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Title |
CosmoLattice: A modern code for lattice simulations of scalar and gauge field dynamics in an expanding universe |
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Journal Article |
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Year |
2023 |
Publication |
Computer Physics Communications |
Abbreviated Journal |
Comput. Phys. Commun. |
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283 |
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108586 - 13pp |
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Early universe; Real-time lattice simulations; Gauge -invariant lattice techniques |
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This paper describes CosmoGattice, a modern package for lattice simulations of the dynamics of interacting scalar and gauge fields in an expanding universe. CosmoGattice incorporates a series of features that makes it very versatile and powerful: i) it is written in C++ fully exploiting the object oriented programming paradigm, with a modular structure and a clear separation between the physics and the technical details, ii) it is MPI-based and uses a discrete Fourier transform parallelized in multiple spatial dimensions, which makes it specially appropriate for probing scenarios with well -separated scales, running very high resolution simulations, or simply very long ones, iii) it introduces its own symbolic language, defining field variables and operations over them, so that one can introduce differential equations and operators in a manner as close as possible to the continuum, iv) it includes a library of numerical algorithms, ranging from O(delta t(2)) to O(delta t(10)) methods, suitable for simulating global and gauge theories in an expanding grid, including the case of 'self-consistent' expansion sourced by the fields themselves. Relevant observables are provided for each algorithm (e.g. energy densities, field spectra, lattice snapshots) and we note that, remarkably, all our algorithms for gauge theories (Abelian or non-Abelian) always respect the Gauss constraint to machine precision. Program summary Program Title:: CosmoGattice CPC Library link to program files: https://doi .org /10 .17632 /44vr5xssc6 .1 Developer's repository link: http://github .com /cosmolattice /cosmolattice Licensing provisions: MIT Programming language: C++, MPI Nature of problem: The phenomenology of high energy physics in the early universe is typically characterized by non-linear dynamics, which cannot be captured accurately with analytical techniques. In order to fully understand the non-linearities developed in a given scenario, one needs to carry out lattice simulations. A number of public packages for lattice simulations have appeared over the years, but most of them are only capable of simulating scalar fields. However, realistic models of particle physics do contain other kind of field species, such as (Abelian or non-Abelian) gauge fields, whose non-linear dynamics can also play a relevant role in the early universe. Tensor modes representing gravitational waves are also naturally expected in many scenarios. Solution method: CosmoGattice represents a modern code for lattice simulations of scalar-gauge field theories in an expanding universe. It allows for the simulation of the evolution of interacting (singlet) scalar fields, charged scalar fields under U(1) and/or SU(2) gauge groups, and the corresponding associated Abelian and/or non-Abelian gauge fields. From version 1.1 onward, CosmoGattice also allows to simulate the production of gravitational waves. Simulations can be done either in a flat space-time background, or in a homogeneous and isotropic (spatially flat) expanding FLRW background. CosmoGattice provides symplectic integrators, with accuracy ranging from O (delta t(2)) up to O(delta t(10)), to simuate the non-linear dynamics of the appropriate fields in comoving three-dimensional lattices. The code is parallelized with MPI, and uses a discrete Fourier Transform parallelized in multiple spatial dimensions, which makes it a very powerful code for probing physical problems with well-separated scales. Moreover, the code has been designed as a `platform' to implement any system of dynamical equations suitable for discretization on a lattice. |
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[Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, Valencia, Spain, Email: f.torrenti@unibas.ch |
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Elsevier |
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0010-4655 |
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WOS:000899506700008 |
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no |
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yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5451 |
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Figueroa, D.G.; Raatikainen, S.; Rasanen, S.; Tomberg, E. |
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Title |
Non-Gaussian Tail of the Curvature Perturbation in Stochastic Ultraslow-Roll Inflation: Implications for Primordial Black Hole Production |
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Journal Article |
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Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
127 |
Issue |
10 |
Pages |
101302 - 7pp |
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We consider quantum diffusion in ultraslow-roll (USR) inflation. Using the Delta N formalism, we present the first stochastic calculation of the probability distribution P(R) of the curvature perturbation during USR. We capture the nonlinearity of the system, solving the coupled evolution of the coarse-grained background with random kicks from the short wavelength modes, simultaneously with the mode evolution around the stochastic background. This leads to a non-Markovian process from which we determine the highly non-Gaussian tail of P(R). Studying the production of primordial black holes in a viable model, we find that stochastic effects during USR increase their abundance by a factor of similar to 10(5) compared with the Gaussian approximation. |
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[Figueroa, Daniel G.] Univ Valencia, Inst Fis Corpuscular IFIC, CSIC, E-46980 Valencia, Spain |
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Amer Physical Soc |
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0031-9007 |
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WOS:000692791400004 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4952 |
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Author |
Figueroa, D.G.; Lizarraga, J.; Urio, A.; Urrestilla, J. |
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Title |
Strong Backreaction Regime in Axion Inflation |
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Journal Article |
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Year |
2023 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
131 |
Issue |
15 |
Pages |
151003 - 7pp |
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We study the nonlinear dynamics of axion inflation, capturing for the first time the inhomogeneity and full dynamical range during strong backreaction, till the end of inflation. Accounting for inhomogeneous effects leads to a number of new relevant results, compared to spatially homogeneous studies: (i) the number of extra efoldings beyond slow-roll inflation increases very rapidly with the coupling, (ii) oscillations of the inflaton velocity are attenuated, (iii) the tachyonic gauge field helicity spectrum is smoothed out (i.e., the spectral oscillatory features disappear), broadened, and shifted to smaller scales, and (iv) the nontachyonic helicity is excited, reducing the chiral asymmetry, now scale dependent. Our results are expected to impact strongly on the phenomenology and observability of axion inflation, including gravitational wave generation and primordial black hole production. |
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[Figueroa, Daniel G.] CSIC, Inst Fis Corpuscular IFIC, Valencia 46980, Spain, Email: daniel.figueroa@ific.uv.es; |
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Amer Physical Soc |
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0031-9007 |
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WOS:001093422100002 |
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no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5783 |
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Author |
Antusch, S.; Figueroa, D.G.; Marschall, K.; Torrenti, F. |
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Energy distribution and equation of state of the early Universe: Matching the end of inflation and the onset of radiation domination |
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2020 |
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Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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811 |
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135888 - 7pp |
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We study the energy distribution and equation of state of the universe between the end of inflation and the onset of radiation domination (RD), considering observationally consistent single-field inflationary scenarios, with a potential 'flattening' at large field values, and a monomial shape V(phi) proportional to vertical bar phi vertical bar(p) around the origin. As a proxy for (p)reheating, we include a quadratic interaction g(2)phi X-2(2) between the inflaton phi and a light scalar 'daughter' field X, with g(2) > 0. We capture the non-perturbative and non-linear nature of the system dynamics with lattice simulations, obtaining that: i) the final energy transferred to X depends only on p, not on g(2); ii) the final transfer of energy is always negligible for 2 <= p < 4, and of order similar to 50% for p >= 4; iii) the system goes at late times to matter-domination for p = 2, and always to RD for p > 2. In the latter case we calculate the number of e-folds until RD, significantly reducing the uncertainty in the inflationary observables Tl-s and r. |
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[Antusch, Stefan; Marschall, Kenneth; Torrenti, Francisco] Univ Basel, Dept Phys, Klingelbergstr 82, CH-4056 Basel, Switzerland, Email: f.torrenti@unibas.ch |
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Elsevier |
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English |
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0370-2693 |
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WOS:000612225400040 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4699 |
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