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1. Constraints on bosonic dark matter from ultralow-field nuclear magnetic resonance

   https://doi.org/10.1126/sciadv.aax4539  

   Garcon, Antoine; Blanchard, John W.; Centers, Gary P.; Figueroa, Nataniel L.; Graham, Peter W.; Jackson Kimball, Derek F.; Rajendran, Surjeet; Sushkov, Alexander O.; Stadnik, Yevgeny V.; Wickenbrock, Arne; et al (October 2019, Science Advances)

   The nature of dark matter, the invisible substance making up over 80% of the matter in the universe, is one of the most fundamental mysteries of modern physics. Ultralight bosons such as axions, axion-like particles, or dark photons could make up most of the dark matter. Couplings between such bosons and nuclear spins may enable their direct detection via nuclear magnetic resonance (NMR) spectroscopy: As nuclear spins move through the galactic dark-matter halo, they couple to dark matter and behave as if they were in an oscillating magnetic field, generating a dark-matter–driven NMR signal. As part of the cosmic axion spin precession experiment (CASPEr), an NMR-based dark-matter search, we use ultralow-field NMR to probe the axion-fermion “wind” coupling and dark-photon couplings to nuclear spins. No dark matter signal was detected above background, establishing new experimental bounds for dark matter bosons with masses ranging from 1.8 × 10 −16 to 7.8 × 10 −14 eV. 

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2. Snowmass2021 Cosmic Frontier: Synergies between dark matter searches and multiwavelength/multimessenger astrophysics

   Ando, S.I.; Baum, S.; Boylan-Kolchin, M.; Bulbul, E.; Burgess, M.; Cholis, I.; von Doetinchem, P.; Fan, J.; Harding, P.J.; Horiuchi, S.; et al (March 2022, ArXivorg)

   This whitepaper focuses on the astrophysical systematics which are encountered in dark matter searches. Oftentimes in indirect and also in direct dark matter searches, astrophysical systematics are a major limiting factor to sensitivity to dark matter. Just as there are many forms of dark matter searches, there are many forms of backgrounds. We attempt to cover the major systematics arising in dark matter searches using photons -- radio and gamma rays -- to cosmic rays, neutrinos and gravitational waves. Examples include astrophysical sources of cosmic messengers and their interactions which can mimic dark matter signatures. In turn, these depend on commensurate studies in understanding the cosmic environment -- gas distributions, magnetic field configurations -- as well as relevant nuclear astrophysics. We also cover the astrophysics governing celestial bodies and galaxies used to probe dark matter, from black holes to dwarf galaxies. Finally, we cover astrophysical backgrounds related to probing the dark matter distribution and kinematics, which impact a wide range of dark matter studies. In the future, the rise of multi-messenger astronomy, and novel analysis methods to exploit it for dark matter, will offer various strategic ways to continue to enhance our understanding of astrophysical backgrounds to deliver improved sensitivity to dark matter. 

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3. Pushing the limits of detectability: mixed dark matter from strong gravitational lenses

   https://doi.org/10.1093/mnras/stad2251  

   Keeley, Ryan_E; Nierenberg, Anna_M; Gilman, Daniel; Birrer, Simon; Benson, Andrew; Treu, Tommaso (July 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT One of the frontiers for advancing what is known about dark matter lies in using strong gravitational lenses to characterize the population of the smallest dark matter haloes. There is a large volume of information in strong gravitational lens images – the question we seek to answer is to what extent we can refine this information. To this end, we forecast the detectability of a mixed warm and cold dark matter scenario using the anomalous flux ratio method from strong gravitational lensed images. The halo mass function of the mixed dark matter scenario is suppressed relative to cold dark matter but still predicts numerous low-mass dark matter haloes relative to warm dark matter. Since the strong lensing signal receives a contribution from a range of dark matter halo masses and since the signal is sensitive to the specific configuration of dark matter haloes, not just the halo mass function, degeneracies between different forms of suppression in the halo mass function, relative to cold dark matter, can arise. We find that, with a set of lenses with different configurations of the main deflector and hence different sensitivities to different mass ranges of the halo mass function, the different forms of suppression of the halo mass function between the warm dark matter model and the mixed dark matter model can be distinguished with 40 lenses with Bayesian odds of 30:1. 

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4. The unique biogeochemical role of carbonate-associated organic matter in a subtropical seagrass meadow

   https://doi.org/10.1038/s43247-024-01832-7  

   Zeller, Mary A; Van_Dam, Bryce R; Lopes, Christian; McKenna, Amy M; Osburn, Christopher L; Fourqurean, James W; Kominoski, John S; Böttcher, Michael Ernst (December 2024, Communications Earth & Environment)

   Abstract The particulate organic matter buried in carbonate-rich seagrass ecosystems is an important blue carbon reservoir. While carbonate sediments are affected by alkalinity produced or consumed in seagrass-mediated biogeochemical processes, little is known about the corresponding impact on organic matter. A portion of particulate organic matter is carbonate-associated organic matter. Here, we explore its biogeochemistry in a carbonate seagrass meadow in central Florida Bay, USA. We couple inorganic stable isotope analyses (δ³⁴S, δ¹⁸O) with a molecular characterization of dissolved and carbonate associated organic matter (21 tesla Fourier-transform ion cyclotron resonance mass spectrometry). We find that carbonate-associated molecular formulas are highly sulfurized compared to surface water dissolved organic matter, with multiple sulfurization pathways at play. Furthermore, 97% of the formula abundance of surface water dissolved organic matter is shared with carbonate-associated organic matter, indicating connectivity between these two pools. We estimate that 9.2% of the particulate organic matter is carbonate-associated, and readily exchangeable with the broader aquatic system as the sediment dissolves and reprecipitates. 

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5. Constraining neutrino-DM interactions with Milky Way dwarf spheroidals and supernova neutrinos

   https://doi.org/10.1103/PhysRevD.110.023004  

   Heston, Sean; Horiuchi, Shunsaku; Shirai, Satoshi (July 2024, Physical Review D)

   We constrain the neutrino-dark matter cross section using properties of the dark matter density profiles of Milky Way dwarf spheroidal galaxies. The constraint arises from core-collapse supernova neutrinos scattering on dark matter as a form of energy injection, allowing the transformation of the dark matter density profile from a cusped profile to a flatter profile. We assume a standard cosmology of dark energy and cold, collisionless, and non-self-interacting dark matter. By requiring that the dark matter cores do not lose too much mass or overshoot constraints from stellar kinematics, we place an upper limit on the cross section of, which is stronger than previous bounds for these energies. Consideration of baryonic feedback or host galaxy effects on the dark matter profile can strengthen this constraint. 

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