Constraints on dark matter annihilation and decay from the large-scale structure of the nearby Universe
Physical Review D American Physical Society 106:10 (2022) 103526
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 mχ7 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=-2.75-0.46+0.71, likely of baryonic origin, is preferred by the data.Testing modified gravity theories with numerical solutions of the external field effect in rotationally supported galaxies
Physical Review D American Physical Society (APS) 106:10 (2022) 103025
The information on halo properties contained in spectroscopic observations of late-type galaxies
(2022)
The effect of local Universe constraints on halo abundance and clustering
Monthly Notices of the Royal Astronomical Society Oxford University Press 516:3 (2022) 3592-3601
Abstract:
Cosmological N-body simulations of the dark matter component of the universe typically use initial conditions with a fixed power spectrum and random phases of the density field, leading to structure consistent with the local distribution of galaxies only in a statistical sense. It is, however, possible to infer the initial phases which lead to the configuration of galaxies and clusters that we see around us. We analyse the CSiBORG suite of 101 simulations, formed by constraining the density field within 155 Mpc h−1 with dark matter particle mass 4.38 × 109 M⊙, to quantify the degree to which constraints imposed on 2.65 Mpc h−1 scales reduce variance in the halo mass function and halo–halo cross-correlation function on a range of scales. This is achieved by contrasting CSiBORG with a subset of the unconstrained Quijote simulations and expectations for the ΛCDM average. Using the FOF, PHEW, and HOP halofinders, we show that the CSiBORG suite beats cosmic variance at large mass scales (≳1014 M⊙ h−1), which are most strongly constrained by the initial conditions, and exhibits a significant halo–halo cross-correlation out to ∼30 Mpc h−1. Moreover, the effect of the constraints percolates down to lower mass objects and to scales below those on which they are imposed. Finally, we develop an algorithm to ‘twin’ haloes between realizations and show that approximately 50 per cent of haloes with mass greater than 1015 M⊙ h−1 can be identified in all realizations of the CSiBORG suite. We make the CSiBORG halo catalogues publicly available for future applications requiring knowledge of the local halo field.Astrophysical Tests of Dark Matter Self-Interactions
(2022)