| 1. |
- Jasche, Jens, et al.
(författare)
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Constraints on equivalence principle violation from gamma ray bursts
- 2021
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Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 104:8
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Tidskriftsartikel (refereegranskat)abstract
- Theories of gravity that obey the weak equivalence principle have the same parametrized post-Newtonian parameter gamma for all particles at all energies. The large Shapiro time delays of extragalactic sources allow us to put tight constraints on differences in gamma between photons of different frequencies from spectral lag data, since a nonzero Delta gamma would result in a frequency-dependent arrival time. The majority of previous constraints have assumed that the Shapiro time delay is dominated by a few local massive objects, although this is a poor approximation for distant sources. In this work we consider the cosmological context of these sources by developing a source-by-source, Monte Carlo-based forward model for the Shapiro time delays by combining constrained realizations of the local density field using the Bayesian origin reconstruction from galaxies algorithm with unconstrained large-scale modes. Propagating uncertainties in the density field reconstruction and marginalizing over an empirical model describing other contributions to the time delay, we use spectral lag data of gamma ray bursts from the BATSE satellite to constrain Delta gamma < 2.1 x 10(-15) at 1 sigma confidence between photon energies of 25 keV and 325 keV.
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| 2. |
- Ballardini, M., et al.
(författare)
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Euclid : The search for primordial features
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 683
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Tidskriftsartikel (refereegranskat)abstract
- Primordial features, in particular oscillatory signals, imprinted in the primordial power spectrum of density perturbations represent a clear window of opportunity for detecting new physics at high-energy scales. Future spectroscopic and photometric measurements from the Euclid space mission will provide unique constraints on the primordial power spectrum, thanks to the redshift coverage and high-accuracy measurement of nonlinear scales, thus allowing us to investigate deviations from the standard power-law primordial power spectrum. We consider two models with primordial undamped oscillations superimposed on the matter power spectrum described by 1 + ?X sin (ωXΞX + 2 πϕX), one linearly spaced in k space with Ξlin ≡ k/k* where k* = 0.05 Mpc−1 and the other logarithmically spaced in k space with Ξlog ≡ ln(k/k*). We note that ?X is the amplitude of the primordial feature, ωX is the dimensionless frequency, and ϕX is the normalised phase, where X = {lin, log}. We provide forecasts from spectroscopic and photometric primary Euclid probes on the standard cosmological parameters Ωm, 0, Ωb, 0, h, ns, and σ8, and the primordial feature parameters ?X, ωX, and ϕX. We focus on the uncertainties of the primordial feature amplitude ?X and on the capability of Euclid to detect primordial features at a given frequency. We also study a nonlinear density reconstruction method in order to retrieve the oscillatory signals in the primordial power spectrum, which are damped on small scales in the late-time Universe due to cosmic structure formation. Finally, we also include the expected measurements from Euclid’s galaxy-clustering bispectrum and from observations of the cosmic microwave background (CMB). We forecast uncertainties in estimated values of the cosmological parameters with a Fisher matrix method applied to spectroscopic galaxy clustering (GCsp), weak lensing (WL), photometric galaxy clustering (GCph), the cross correlation (XC) between GCph and WL, the spectroscopic galaxy clustering bispectrum, the CMB temperature and E-mode polarisation, the temperature-polarisation cross correlation, and CMB weak lensing. We consider two sets of specifications for the Euclid probes (pessimistic and optimistic) and three different CMB experiment configurations, that is, Planck, Simons Observatory (SO), and CMB Stage-4 (CMB-S4). We find the following percentage relative errors in the feature amplitude with Euclid primary probes: for the linear (logarithmic) feature model, with a fiducial value of ?X = 0.01, ωX = 10, and ϕX = 0: 21% (22%) in the pessimistic settings and 18% (18%) in the optimistic settings at a 68.3% confidence level (CL) using GCsp+WL+GCph+XC. While the uncertainties on the feature amplitude are strongly dependent on the frequency value when single Euclid probes are considered, we find robust constraints on ?X from the combination of spectroscopic and photometric measurements over the frequency range of (1, 102.1). Due to the inclusion of numerical reconstruction, the GCsp bispectrum, SO-like CMB reduces the uncertainty on the primordial feature amplitude by 32%–48%, 50%–65%, and 15%–50%, respectively. Combining all the sources of information explored expected from Euclid in combination with the future SO-like CMB experiment, we forecast ?lin ≃ 0.010 ± 0.001 at a 68.3% CL and ?log ≃ 0.010 ± 0.001 for GCsp(PS rec + BS)+WL+GCph+XC+SO-like for both the optimistic and pessimistic settings over the frequency range (1, 102.1).
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| 3. |
- Bartlett, D. J., et al.
(författare)
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Constraints on dark matter annihilation and decay from the large-scale structure of the nearby Universe
- 2022
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 106:10
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Tidskriftsartikel (refereegranskat)abstract
- Decaying or annihilating dark matter particles could be detected through gamma-ray emission from the species they decay or annihilate into. This is usually done by modeling the flux from specific dark matter–rich objects such as the Milky Way halo, Local Group dwarfs, and nearby groups. However, these objects are expected to have significant emission from baryonic processes as well, and the analyses discard gamma-ray data over most of the sky. Here we construct full-sky templates for gamma-ray flux from the large-scale structure within ∼200 Mpc by means of a suite of constrained N-body simulations (csiborg) produced using the Bayesian Origin Reconstruction from Galaxies algorithm. Marginalizing over uncertainties in this reconstruction, small-scale structure, and parameters describing astrophysical contributions to the observed gamma-ray sky, we compare to observations from the Fermi Large Area Telescope to constrain dark matter annihilation cross sections and decay rates through a Markov chain Monte Carlo analysis. We rule out the thermal relic cross section for s-wave annihilation for all mχ≲7 GeV/c2 at 95% confidence if the annihilation produces gluons or quarks less massive than the bottom quark. We infer a contribution to the gamma-ray sky with the same spatial distribution as dark matter decay at 3.3σ. Although this could be due to dark matter decay via these channels with a decay rate Γ≈6×10−28 s−1, we find that a power-law spectrum of index p=−2.75+0.71−0.46, likely of baryonic origin, is preferred by the data.
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| 4. |
- Bartlett, D. J., et al.
(författare)
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Constraints on quantum gravity and the photon mass from gamma ray bursts
- 2021
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 104:10
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Tidskriftsartikel (refereegranskat)abstract
- Lorentz invariance violation in quantum gravity (QG) models or a nonzero photon mass, mγ, would lead to an energy-dependent propagation speed for photons, such that photons of different energies from a distant source would arrive at different times, even if they were emitted simultaneously. By developing source-by-source, Monte Carlo-based forward models for such time delays from gamma ray bursts, and marginalizing over empirical noise models describing other contributions to the time delay, we derive constraints on mγ and the QG length scale, ℓQG, using spectral lag data from the BATSE satellite. We find mγ<4.0×10−5 h eV/c2 and ℓQG<5.3×10−18 h GeV−1 at 95% confidence, and demonstrate that these constraints are robust to the choice of noise model. The QG constraint is among the tightest from studies which consider multiple gamma ray bursts and the constraint on mγ, although weaker than from using radio data, provides an independent constraint which is less sensitive to the effects of dispersion by electrons.
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| 5. |
- Boulanger, Francois, et al.
(författare)
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IMAGINE : a comprehensive view of the interstellar medium, Galactic magnetic fields and cosmic rays
- 2018
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :8
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Tidskriftsartikel (refereegranskat)abstract
- In this white paper we introduce the IMAGINE Consortium and its scientific background, goals and structure. The purpose of the consortium is to coordinate and facilitate the efforts of a diverse group of researchers in the broad areas of the interstellar medium, Galactic magnetic fields and cosmic rays, and our overarching goal is to develop more comprehensive insights into the structures and roles of interstellar magnetic fields and their interactions with cosmic rays within the context of Galactic astrophysics. The ongoing rapid development of observational and numerical facilities and techniques has resulted in a widely felt need to advance this subject to a qualitatively higher level of self-consistency, depth and rigour. This can only be achieved by the coordinated efforts of experts in diverse areas of astrophysics involved in observational, theoretical and numerical work. We present our view of the present status of this research area, identify its key unsolved problems and suggest a strategy that will underpin our work. The backbone of the consortium is the Interstellar MAGnetic field INference Engine, a publicly available Bayesian platform that employs robust statistical methods to explore the multi-dimensional likelihood space using any number of modular inputs. This tool will be used by the IMAGINE Consortium to develop an interpretation and modelling framework that provides the method, power and flexibility to interfuse information from a variety of observational, theoretical and numerical lines of evidence into a self-consistent and comprehensive picture of the thermal and non-thermal interstellar media. An important innovation is that a consistent understanding of the phenomena that are directly or indirectly influenced by the Galactic magnetic field, such as the deflection of ultra-high energy cosmic rays or extragalactic backgrounds, is made an integral part of the modelling. The IMAGINE Consortium, which is informal by nature and open to new participants, hereby presents a methodological framework for the modelling and understanding of Galactic magnetic fields that is available to all communities whose research relies on a state of the art solution to this problem.
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| 6. |
- Charnock, Tom, et al.
(författare)
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Neural physical engines for inferring the halo mass distribution function
- 2020
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 494:1, s. 50-61
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Tidskriftsartikel (refereegranskat)abstract
- An ambitious goal in cosmology is to forward model the observed distribution of galaxies in the nearby Universe today from the initial conditions of large-scale structures. For practical reasons, the spatial resolution at which this can be done is necessarily limited. Consequently, one needs a mapping between the density of dark matter averaged over similar to Mpc scales and the distribution of dark matter haloes (used as a proxy for galaxies) in the same region. Here, we demonstrate a method for determining the halo mass distribution function by learning the tracer bias between density fields and halo catalogues using a neural bias model. The method is based on the Bayesian analysis of simple, physically motivated, neural network-like architectures, which we denote as neural physical engines, and neural density estimation. As a result, we are able to sample the initial phases of the dark matter density field while inferring the parameters describing the halo mass distribution function, providing a fully Bayesian interpretation of both the initial dark matter density distribution and the neural bias model. We successfully run an upgraded BORG (Bayesian Origin Reconstruction from Galaxies) inference using our new likelihood and neural bias model with halo catalogues derived from full N-body simulations. In preliminary results, we notice there could potentially be orders of magnitude improvement in modelling compared to classical biasing techniques.
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| 7. |
- Dálya, G., et al.
(författare)
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GLADE + : an extended galaxy catalogue for multimessenger searches with advanced gravitational-wave detectors
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 514:1, s. 1403-1411
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Tidskriftsartikel (refereegranskat)abstract
- We present GLADE+, an extended version of the GLADE galaxy catalogue introduced in our previous paper for multimessenger searches with advanced gravitational-wave detectors. GLADE+ combines data from six separate but not independent astronomical catalogues: the GWGC, 2MPZ, 2MASS XSC, HyperLEDA, and WISExSCOSPZ galaxy catalogues, and the SDSS-DR16Q quasar catalogue. To allow corrections of CMB-frame redshifts for peculiar motions, we calculated peculiar velocities along with their standard deviations of all galaxies having B-band magnitude data within redshift z = 0.05 using the ‘Bayesian Origin Reconstruction from Galaxies’ formalism. GLADE+ is complete up to luminosity distance dL=47+4−2 Mpc in terms of the total expected B-band luminosity of galaxies, and contains all of the brightest galaxies giving 90 per cent of the total B-band and K-band luminosity up to dL ≃ 130 Mpc. We include estimations of stellar masses and individual binary neutron star merger rates for galaxies with W1 magnitudes. These parameters can help in ranking galaxies in a given gravitational wave localization volume in terms of their likelihood of being hosts, thereby possibly reducing the number of pointings and total integration time needed to find the electromagnetic counterpart.
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| 8. |
- Desmond, Harry, et al.
(författare)
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Fifth force constraints from galaxy warps
- 2018
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 98:8
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Tidskriftsartikel (refereegranskat)abstract
- Intragalaxy signals contain a wealth of information on fundamental physics, both the dark sector and the nature of gravity. While so far largely unexplored, such probes are set to rise dramatically in importance as upcoming surveys provide data of unprecedented quantity and quality on galaxy structure and dynamics. In this paper, we use warping of stellar disks to test the chameleon-or symmetron-screened fifth forces which generically arise when new fields couple to matter. We take r-band images of mostly late-type galaxies from the Nasa Sloan Atlas and develop an automated algorithm to quantify the degree of U-shaped warping they exhibit. We then forward model the warp signal as a function of fifth-force strength, Delta G/G(N), and range, lambda(C), and the gravitational environments and internal properties of the galaxies, including full propagation of the non-Gaussian uncertainties. Convolving this fifth-force likelihood function with a Gaussian describing astrophysical and observational noise and then constraining Delta G/G(N) and lambda(C) by Markov chain Monte Carlo, we find the overall likelihood to be significantly increased (Delta log (L) similar or equal to 20) by adding a screened fifth force with lambda(C) similar or equal to 2 Mpc and Delta G/G(N) similar or equal to 0.01. The variation of Delta log (L) with lambda(C) is quantitatively as expected from the correlation of the magnitude of the fifth-force field with the force's range, and a similar model without screening achieves no increase in likelihood over the General Relativistic case Delta G = 0. Although these results are in good agreement with a previous analysis of the same model using offsets between galaxies' stellar and gas mass centroids [H. Desmond et al., Phys. Rev. D 98, 064015 (2018).], we caution that the effects of confounding baryonic and dark matter physics must be thoroughly investigated for the results of the inference to be unambiguous.
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| 9. |
- Desmond, Harry, et al.
(författare)
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Fifth force constraints from the separation of galaxy mass components
- 2018
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 98:6
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Tidskriftsartikel (refereegranskat)abstract
- One of the most common consequences of extensions to the standard models of particle physics or cosmology is the emergence of a fifth force. While generic fifth forces are tightly constrained at Solar System scales and below, they may escape detection by means of a screening mechanism which effectively removes them in dense environments. We constrain the strength Delta G/G(N) and range lambda(C) of a fifth force with Yukawa coupling arising from a chameleon-or symmetron-screened scalar field-as well as an unscreened fifth force with differential coupling to galactic mass components-by searching for the displacement it predicts between galaxies' stellar and gas mass centroids. Taking data from the Alfalfa survey of neutral atomic hydrogen (HI), identifying galaxies' gravitational environments with the maps of [H. Desmond, P.G. Ferreira, G. Lavaux, and J. Jasche, Mon. Not. R. Astron. Soc. 474, 3152 (2018)] and forward modeling with a Bayesian likelihood framework, we find, with screening included, 6.6 sigma evidence for Delta G > 0 at lambda(C) greater than or similar to 2 Mpc. The maximum-likelihood Delta G/G(N) is 0.025. A similar fifth force model without screening gives no increase in likelihood over the case Delta G = 0 for any lambda(C). Although we validate this result by several methods, we do not claim screened modified gravity to provide the only possible explanation for the data: this conclusion would require knowing that the signal could not be produced by galaxy formation physics. We show also the results of a more conservative-though less well-motivated-noise model which yields only upper limits on Delta G/G(N), ranging from similar to 10(-1) for lambda(C) similar or equal to 0.5 Mpc to similar to few x 10(-4) at lambda(C) similar or equal to 50 Mpc. Corresponding models without screening receive the somewhat stronger bounds similar to few x 10(-3) and similar to few x 10(-4) respectively. We show how these constraints may be improved by future galaxy surveys and identify the key features of an observational program for directly constraining fifth forces on scales beyond the Solar System. This paper provides a complete description of the analysis summarized in [H. Desmond, P.G. Ferreira, G. Lavaux, and J. Jasche, arXiv:1802.07206].
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| 10. |
- Desmond, Harry, et al.
(författare)
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The fifth force in the local cosmic web
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966 .- 1745-3925 .- 1745-3933. ; 483:1, s. l64-L68
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Tidskriftsartikel (refereegranskat)abstract
- Extensions of the standard models of particle physics and cosmology often lead to long-range fifth forces with properties dependent on gravitational environment. Fifth forces on astrophysical scales are best studied in the cosmic web where perturbation theory breaks down. We present constraints on chameleon-and symmetron-screened fifth forces with Yukawa coupling and megaparsec range - as well as unscreened fifth forces with differential coupling to galactic mass components - by searching for the displacements they predict between galaxies' stars and gas. Taking data from the Alfalfa HI survey, identifying galaxies' gravitational environments with the maps of Desmond et al. and forward modelling with a Bayesian likelihood framework, we set upper bounds on fifth-force strength relative to Newtonian gravity from similar to few x 10(-4) (1 sigma) for range lambda(C) = 50 Mpc, to similar to 0.1 for lambda(C) = 500 kpc. In f(R) gravity this requires f(R0) <= few x 10(-8). The analogous bounds without screening are similar to few x 10(-4) and few x 10(-3). These are the tightest and among the only fifth-force constraints on galaxy scales. We show how our results may be strengthened with future survey data and identify the key features of an observational programme for furthering fifth-force tests beyond the Solar system.
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