分类： 天文学 >> 天文学 提交时间： 2023-02-19
Zhichao Carton Zeng
Annika H. G. Peter
Xiaolong Du
Andrew Benson
Stacy Kim
Fangzhou Jiang
Francis-Yan Cyr-Racine
Mark Vogelsberger
摘要： Self-interacting dark matter (SIDM) cosmologies admit an enormous diversity of dark matter (DM) halo density profiles, from low-density cores to high-density core-collapsed cusps. The possibility of the growth of high central density in low-mass halos, accelerated if halos are subhalos of larger systems, has intriguing consequences for small-halo searches with substructure lensing. However, following the evolution of $\lesssim 10^8 M_\odot$ subhalos in lens-mass systems ($\sim 10^{13}M_\odot$) is computationally expensive with traditional N-body simulations. In this work, we develop a new hybrid semi-analytical + N-body method to study the evolution of SIDM subhalos with high fidelity, from core formation to core-collapse, in staged simulations. Our method works best for small subhalos ($\lesssim 1/1000$ host mass), for which the error caused by dynamical friction is minimal. We are able to capture the evaporation of subhalo particles by interactions with host halo particles, an effect that has not yet been fully explored in the context of subhalo core-collapse. We find three main processes drive subhalo evolution: subhalo internal heat outflow, host-subhalo evaporation, and tidal effects. The subhalo central density grows only when the heat outflow outweighs the energy gain from evaporation and tidal heating. Thus, evaporation delays or even disrupts subhalo core-collapse. We map out the parameter space for subhalos to core-collapse, finding that it is nearly impossible to drive core-collapse in subhalos in SIDM models with constant cross sections. Any discovery of ultra-compact dark substructures with future substructure lensing observations favors additional degrees of freedom, such as velocity-dependence, in the cross section.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We use here a family of scaling transformations, that scale key rates in the evolution equations, to analytically understand constraints on light relics from cosmic microwave background (CMB) maps, given cosmological models of varying degrees of complexity. We describe the causes of physical effects that are fundamentally important to the constraining power of the data, with a focus on the two that are most novel. We use as a reference model a cosmological model that admits a scaling transformation that increases light relic energy density while avoiding all of these causes. Constraints on light relics in a given model can then be understood as due to the differences between the given model and the reference model, as long as the additional light relics only interact gravitationally with the Standard Model components. This understanding supports the development of cosmological models that can evade light relics constraints from CMB maps.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Alex Drlica-Wagner
Chanda Prescod-Weinstein
Hai-Bo Yu
Andrea Albert
Mustafa Amin
Arka Banerjee
Masha Baryakhtar
Keith Bechtol
Simeon Bird
Simon Birrer
Torsten Bringmann
Regina Caputo
Sukanya Chakrabarti
Thomas Y. Chen
Djuna Croon
Francis-Yan Cyr-Racine
William A. Dawson
Cora Dvorkin
Vera Gluscevic
Daniel Gilman
摘要： Cosmological and astrophysical observations currently provide the only robust, positive evidence for dark matter. Cosmic probes of dark matter, which seek to determine the fundamental properties of dark matter through observations of the cosmos, have emerged as a promising means to reveal the nature of dark matter. This report summarizes the current status and future potential of cosmic probes to inform our understanding of the fundamental nature of dark matter in the coming decade.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Yao-Yuan Mao
Annika H. G. Peter
Susmita Adhikari
Keith Bechtol
Simeon Bird
Simon Birrer
Jonathan Blazek
Jeffrey L. Carlin
Nushkia Chamba
Johann Cohen-Tanugi
Francis-Yan Cyr-Racine
Tansu Daylan
Birendra Dhanasingham
Alex Drlica-Wagner
Cora Dvorkin
Christopher Fassnacht
Eric Gawiser
Maurizio Giannotti
Vera Gluscevic
Alma Gonzalez-Morales
摘要： Establishing that Vera C. Rubin Observatory is a flagship dark matter experiment is an essential pathway toward understanding the physical nature of dark matter. In the past two decades, wide-field astronomical surveys and terrestrial laboratories have jointly created a phase transition in the ecosystem of dark matter models and probes. Going forward, any robust understanding of dark matter requires astronomical observations, which still provide the only empirical evidence for dark matter to date. We have a unique opportunity right now to create a dark matter experiment with Rubin Observatory Legacy Survey of Space and Time (LSST). This experiment will be a coordinated effort to perform dark matter research, and provide a large collaborative team of scientists with the necessary organizational and funding supports. This approach leverages existing investments in Rubin. Studies of dark matter with Rubin LSST will also guide the design of, and confirm the results from, other dark matter experiments. Supporting a collaborative team to carry out a dark matter experiment with Rubin LSST is the key to achieving the dark matter science goals that have already been identified as high priority by the high-energy physics and astronomy communities.
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