Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E09: Dark Matter Theory and CosmologyLive
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Sponsoring Units: DAP Chair: Christopher Fryer, LANL |
Saturday, April 17, 2021 3:45PM - 3:57PM Live |
E09.00001: Sterile Neutrino Dark Matter via Secret Neutrino Interactions Walter Tangarife I will present the anatomy of production mechanisms for sterile neutrino dark matter in the presence of new interactions among either active or sterile neutrinos. These new interactions can be mediated by a scalar or a vector, and allow sterile neutrinos to make up all the dark matter while safely evading all current experimental bounds. We identify three regimes of the mediator’s mass and coupling where it makes a distinct impact on dark matter production through the dispersion relations and/or scattering rates. These models serve as a well-motivated target for the upcoming experimental searches. [Preview Abstract] |
Saturday, April 17, 2021 3:57PM - 4:09PM Live |
E09.00002: Using PySiUltraLight to Model Scalar Dark Matter with Self-Interactions Noah Glennon, Chanda Prescod-Weinstein We introduce PySiUltraLight, a modification of the PyUltraLight code that includes self-interaction terms to model the evolution of axion fields. PyUltraLight simulates ultralight dark matter dynamics. We use a boson mass of $10^{-22} \mathrm{eV}/\mathrm{c}^2$ in this talk. We use PySiUltraLight to produce collapsing solitons, spatially oscillating solitons, and exploding solitons which prior analytic work shows will occur with attractive self-interactions. We test the maximum mass criteria described in arXiv:1604.05904 for a soliton to collapse when attractive self-interactions are included. We find the oscillation frequency as a function of soliton mass and equilibrium radius with attractive self-interactions. We verify that when the soliton mass is below the critical mass described in arXiv:1604.05904 and the initial radius is within a specific range, solitons explode. We also analyze binary soliton collisions and a soliton rotating around a central mass with attractive and repulsive self-interactions. We also find that a soliton is less susceptible to tidal stripping when attractive self-interactions are included. We find that the opposite is true for repulsive self-interactions in that solitons would be more easily tidally stripped. [Preview Abstract] |
Saturday, April 17, 2021 4:09PM - 4:21PM Live |
E09.00003: Assessing Mixed Sterile Neutrino Dark Matter Models Isabella Ianora, Anton Navazo, Chad Kishimoto Recent X-ray observations of galaxies and galaxy clusters suggest the existence of sterile neutrino dark matter with a mass of 7.1 keV. However, there is tension between calculated dark matter spectra and observations of small scale structure. In this talk, I will discuss a variety of mixed dark matter models, comprised of both cold dark matter and sterile neutrinos, whose inferred parameters are consistent with the X-ray observations.We assess the compatibility of these models in comparison to cosmological observables. [Preview Abstract] |
Saturday, April 17, 2021 4:21PM - 4:33PM Live |
E09.00004: Higher Spin Dark Matter Leah Jenks, Stephon Alexander, Evan McDonough Little is known about dark matter beyond the fact that it does not interact with the standard model or itself, or else does so incredibly weakly. A natural candidate, given the history of no-go theorems against their interactions, are higher spin fields. In this talk, I will discuss the scenario of higher spin (spin $s>2$) dark matter. I will show that the gravitational production of superheavy bosonic higher spin fields during inflation can provide all the dark matter we observe today. Then, I will consider the observable signatures, and show a potential characteristic signature of bosonic higher spin dark matter in directional direct detection; distinct spin-dependent contributions to the double differential recoil rate, which complement the oscillatory imprint of higher spin fields in the cosmic microwave background. Lastly, I will speculate on the extension to higher spin fermions and supersymmetric higher spins as well as other potential detection strategies. [Preview Abstract] |
Saturday, April 17, 2021 4:33PM - 4:45PM Live |
E09.00005: Scaling Density of Axion Strings Asier Lopez-Eiguren, Mark Hindmarsh, Joanes Lizarraga, Jon Urrestilla In the QCD axion dark matter scenario with post-inflationary Peccei-Quinn symmetry breaking, the number density of axions, and hence the dark matter density, depends on the length of string per unit volume at cosmic time $t$, by convention written $\zeta/t^2$. The expectation has been that the dimensionless parameter $\zeta$ tends to a constant $\zeta_0$, a feature of a string network known as scaling. It has recently been claimed that in larger numerical simulations $\zeta$ shows a logarithmic increase with time. This case would result in a large enhancement of the string density at the QCD transition, and a substantial revision to the axion mass required for the axion to constitute all of the dark matter. With a set of new simulations of global strings we compare the standard scaling (constant-$\zeta$) model to the logarithmic growth. We conclude that the apparent corrections to $\zeta$ are artefacts of the initial conditions, rather than a property of the scaling network. The residuals from the constant-$\zeta$ (linear $\xi$) fit also show no evidence for logarithmic growth, restoring confidence that numerical simulations can be simply extrapolated from the Peccei-Quinn symmetry-breaking scale to the QCD scale. In this scenario the axion mass should be increased by about50$\%$ [Preview Abstract] |
Saturday, April 17, 2021 4:45PM - 4:57PM Live |
E09.00006: The Core-Envelope Structure of Halos in Scalar Field Dark Matter with Repulsive Self-Interaction Taha Dawoodbhoy, Paul Shapiro, Tanja Rindler-Daller Scalar Field Dark Matter (SFDM) comprised of ultralight (\textgreater \textasciitilde 10$^{\mathrm{-22}}$ eV) bosons was proposed as an alternative to standard Cold Dark Matter (CDM) because of its novel structure-formation dynamics as a Bose-Einstein condensate and quantum superfluid, described by the Gross-Pitaevski and Poisson equations. In the free-field (``fuzzy'') limit of SFDM (FDM), structure is inhibited below the de Broglie wavelength, $\lambda_{\mathrm{deB}}$, but resembles CDM on larger scales. Virialized haloes have solitonic cores of radius \textasciitilde $\lambda_{\mathrm{deB}}$, surrounded by CDM-like envelopes. When a strong enough repulsive self-interaction (SI) is also present, structure can be inhibited below a second length scale, $\lambda _{\mathrm{SI}}$, with $\lambda_{\mathrm{SI}}$ \textgreater $\lambda _{\mathrm{deB}}$ -- the Thomas-Fermi (TF) regime. Structure formation in the TF regime differs significantly from FDM. We present new results for the internal structure of haloes that form from gravitational instability in the TF regime, including comparison with rotation curves of dwarf galaxies in the local universe. The cosmological context and large-scale structure formation for this model will be discussed in a second talk to follow. [Preview Abstract] |
Saturday, April 17, 2021 4:57PM - 5:09PM Live |
E09.00007: Cosmological Structure Formation in Scalar Field Dark Matter with Repulsive Self-Interaction Paul Shapiro, Taha Dawoodbhoy Scalar Field Dark Matter (SFDM) comprised of ultralight (\textgreater \textasciitilde 10$^{\mathrm{-22}}$ eV) bosons was proposed as an alternative to standard Cold Dark Matter (CDM) because of its novel structure-formation dynamics as a Bose-Einstein condensate and quantum superfluid, described by the Gross-Pitaevski and Poisson equations. In the free-field (``fuzzy'') limit of SFDM (FDM), structure is inhibited below the de Broglie wavelength, $\lambda_{\mathrm{deB}}$, but resembles CDM on larger scales. Virialized haloes have solitonic cores of radius \textasciitilde $\lambda_{\mathrm{deB}}$, surrounded by CDM-like envelopes. When a strong enough repulsive self-interaction (SI) is also present, structure can be inhibited below a second length scale, $\lambda _{\mathrm{SI}}$, with $\lambda_{\mathrm{SI}}$ \textgreater $\lambda _{\mathrm{deB}}$ -- the Thomas-Fermi (TF) regime. Structure formation in the TF regime differs significantly from FDM. Our first talk discussed the internal structure of haloes that form from gravitational instability in the TF regime. Here we revisit this in the context of halo and large-scale structure formation from cosmological perturbations, including observational constraints. [Preview Abstract] |
Saturday, April 17, 2021 5:09PM - 5:21PM Live |
E09.00008: Relaxation times for Bose-Einstein condensation in axion miniclusters Anthony E. Mirasola, Kay Kirkpatrick, Chanda Prescod-Weinstein Axions and other scalar dark matter in gravitationally bound miniclusters or dark matter halos are expected to condense into Bose-Einstein condensates called Bose stars. This process has been shown to occur either through attractive self-interactions of the axion-like particles or through the field's self gravitation. We show that in the high-occupancy regime of scalar dark matter, the Boltzmann collision integral does not describe either gravitational or self-interactions, and derive kinetic equations valid for both these interactions. We use this formalism to compute relaxation times for the Bose-Einstein condensation, and find that condensation into Bose stars could occur within the lifetime of the universe. The self-interactions reduce the condensation time only when they are very strong. [Preview Abstract] |
Saturday, April 17, 2021 5:21PM - 5:33PM Live |
E09.00009: An algorithm to locate the centers of baryon acoustic oscillations in real-space Zachery Brown, Regina Demina, Gebri Mishtaku, Chad Popik Acoustic waves in the primordial Universe (baryon acoustic oscillations, BAO) generated spherical shells of matter over-density, which can be detected today in redshift surveys as a preferential length scale between galaxies. We report on an algorithm, CenterFinder, which extends BAO detection beyond a simple length scale, to include the cosmic locations of these primordial over-densities in real-space. Our method creates a model template of the expected matter distribution around over-dense BAO centers, then convolves it with the matter density distribution as traced by galaxies to achieve this goal. Using mock galaxy catalogs, we evaluate the success and robustness of the algorithm by cross-correlating our probable BAO centers with the galaxies themselves. This method is a new and unique probe of the BAO length scale, in addition to its ability to locate BAO centers in real-space. [Preview Abstract] |
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