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Dark matter & dark energy : the hidden 95% of the universe
Since the 1970s, astronomers have been aware that galaxies have far too little matter in them to account for the way they spin around: they should fly apart like clay off a potter's wheel, but something concealed holds them together. This 'something' is dark matter - invisible material in five times the quantity of the familiar stuff of stars and planets. By the 1990s we also knew that the expansion of the universe was accelerating. Something, named dark energy, was pushing it to expand faster and faster. Across the universe, this requires enough energy that the equivalent mass would be nearly 14 times greater than all the known material in existence. With dark matter and dark energy making up 95 per cent of reality, cosmologists have uncovered the biggest puzzle that science has ever faced.
Book
Ultra-light dark matter
Ultra-light dark matter is a class of dark matter models (DM), where DM is composed by bosons with masses ranging from 10-24eV
Journal Article
The dark matter problem : a historical perspective
\"Most astronomers and physicists now believe that the matter content of the Universe is dominated by dark matter: hypothetical particles which interact with normal matter primarily through the force of gravity. Though invisible to current direct detection methods, dark matter can explain a variety of astronomical observations. This book describes how this theory has developed over the past 75 years, and why it is now a central feature of extragalactic astronomy and cosmology. Current attempts to directly detect dark matter locally are discussed, together with the implications for particle physics. The author comments on the sociology of these developments, demonstrating how and why scientists work and interact. Modified Newtonian Dynamics (MOND), the leading alternative to this theory, is also presented. This fascinating overview will interest cosmologists, astronomers and particle physicists. Mathematics is kept to a minimum, so the book can be understood by non-specialists\"--Provided by publisher.
Book
COZMIC. I. Cosmological Zoom-in Simulations with Initial Conditions Beyond Cold Dark Matter
We present 72 cosmological dark-matter--only N-body zoom-in simulations with initial conditions beyond cold, collisionless dark matter (CDM), as the first installment of the COZMIC suite. We simulate Milky Way (MW) analogs with linear matter power spectra P(k) for (i) thermal-relic warm dark matter (WDM) with masses mWDM ∈ [3, 4, 5, 6, 6.5, 10]keV, (ii) fuzzy dark matter (FDM) with masses mFDM ∈ [25.9,69.4, 113, 151, 185, 490] × 10−22eV, and (iii) interacting dark matter (IDM) with a velocity-dependent elastic proton scattering cross section σ = σ0vn, relative particle velocity scaling n ∈ [2, 4], and dark matter mass mIDM ∈ [10−4, 10−2, 1] GeV. Subhalo mass function (SHMF) suppression is significantly steeper in FDM versus WDM, while dark acoustic oscillations in P(k) can reduce SHMF suppression for IDM. We fit SHMF models to our simulation results and derive new bounds on WDM and FDM from the MW satellite population, obtaining mWDM > 5.9 keV and mFDM > 1.4 × 10−20 eV at 95% confidence; these limits are ≈10% weaker and 5× stronger than previous constraints owing to the updated transfer functions and SHMF models, respectively. We estimate IDM bounds for n = 2 (n = 4) and obtain σ0 < 1.0 × 10−27 cm2, 1.3 × 10−24 cm2, and 3.1 × 10−23 cm2 (σ0 < 9.9 × 10−27 cm2, 9.8 × 10−21 cm2, and 2.1 × 10−17 cm2) for mIDM = 10−4, 10−2, and 1 GeV, respectively. Thus, future development of IDM SHMF models can improve IDM cross section bounds by up to a factor of ∼20 with current data. COZMIC presents an important step toward accurate small-scale structure modeling in beyond-CDM cosmologies, critical to upcoming observational searches for dark matter physics.
Journal Article
The elephant in the universe : our hundred-year search for dark matter
\"If existing models of the structure of the universe are correct, then 85 percent of the cosmos comprises a substance called dark matter. Yet no direct evidence of dark matter exists. Award-winning science journalist Govert Schilling details the quest to detect dark matter and how the search has helped us to understand the universe we inhabit\"-- Provided by publisher.
BOOK
COZMIC. II. Cosmological Zoom-in Simulations with Fractional non-CDM Initial Conditions
We present 24 cosmological dark matter (DM)-only zoom-in simulations of a Milky Way analog with initial conditions appropriate for scenarios where non-cold dark matter (NCDM) is a fraction of the total DM abundance (f-NCDM models) as the second installment of the COZMIC suite. We initialize our simulations using transfer functions, Tf−NCDM(k)≡Pf−NCDM(k)/PCDM(k) (where P(k) is the linear matter power spectrum), with an initial suppression similar to thermal-relic warm dark matter (WDM) followed by a constant-amplitude plateau. We simulate suppression wavenumbers [22.8, 32.1, 41.8, 52.0, 57.1, 95.3] Mpc−1, corresponding to thermal-relic WDM masses mWDM ∈ [3, 4, 5, 6, 6.5, 10] keV, and plateau amplitudes δ ∈ [0.2, 0.4, 0.6, 0.8]. We model the subhalo mass function in terms of the suppression wave number and δ. Integrating these models into a forward model of the MW satellite galaxy population yields new limits on f-NCDM scenarios, with suppression wavenumbers greater than 46 and 40 Mpc−1 for δ = 0.2 and 0.4, respectively, at 95% confidence. The current data do not constrain δ > 0.4. We map these limits to scenarios where a fraction fWDM of DM behaves as a thermal relic, which yields the following bounds on cosmologies with a mixture of WDM and CDM: mWDM > 3.6, 4.1, 4.6, 4.9, 5.4 keV for fWDM = 0.5, 0.6, 0.7, 0.8, 0.9, respectively, at 95% confidence. The current data do not constrain WDM fractions fWDM < 0.5. Our results affirm that low-mass halo abundances are sensitive to partial suppression in P(k), indicating the possibility of using galactic substructure to reconstruct P(k) on small scales.
Journal Article
Simulating Atomic Dark Matter in Milky Way Analogs
Dark sector theories naturally lead to multicomponent scenarios for dark matter where a subcomponent can dissipate energy through self-interactions, allowing it to efficiently cool inside galaxies. We present the first cosmological hydrodynamical simulations of Milky Way analogs where the majority of dark matter is collisionless cold dark matter (CDM) but a subcomponent (6%) is strongly dissipative minimal atomic dark matter (ADM). The simulations, implemented in GIZMO and utilizing FIRE-2 galaxy formation physics to model the standard baryonic sector, demonstrate that the addition of even a small fraction of dissipative dark matter can significantly impact galactic evolution despite being consistent with current cosmological constraints. We show that ADM gas with roughly standard model–like masses and couplings can cool to form a rotating “dark disk” with angular momentum closely aligned with the visible stellar disk. The morphology of the disk depends sensitively on the parameters of the ADM model, which affect the cooling rates in the dark sector. The majority of the ADM gas gravitationally collapses into dark “clumps” (regions of black hole or mirror star formation), which form a prominent bulge and a rotating thick disk in the central galaxy. These clumps form early and quickly sink to the inner ∼kiloparsec of the galaxy, affecting the galaxy’s star formation history and present-day baryonic and CDM distributions.
Journal Article
Einstein's telescope : the hunt for dark matter and dark energy in the universe
Evalyn Gates transports us to the edge of science to explore the tool that unlocks the secrets of dark matter and dark energy. Based on the theory of general relativity, gravitational lensing, or 'Einstein's Telescope', is enabling discoveries that are taking us towards the next revolution in scientific thinking--one that may change our understanding of where the Universe came from and where it is going.
BOOK
The Z 7 model of three-component scalar dark matter
Abstract We investigate, for the first time, a scenario where the dark matter consists of three complex scalar fields that are stabilized by a single Z 7 symmetry. As an extension of the well-known scalar Higgs-portal, this Z 7 model is also subject to important restrictions arising from the relic density constraint and from direct detection experiments. Our goal in this paper is to find and characterize the viable regions of this model, and to analyze its detection prospects in future experiments. First, the processes that affect the relic densities are identified (they include semiannihilations and conversions) and then incorporated into the Boltzmann equations for the dark matter abundances, which are numerically solved with micrOMEGAs. By means of random scans of the parameter space, the regions consistent with current data, including the recent direct detection limit from the LZ experiment, are selected. Our results reveal that the Z 7 model is indeed viable over a wide range of dark matter masses and that both conversions and semiannihilations play an important role in determining the relic densities. Remarkably, we find that in many cases all three of the dark matter particles give rise to observable signals in future direct detection experiments, providing a suitable way to test this scenario.
Journal Article