Search Publications
Cosmic Coincidences of Primordial-Black-Hole Dark Matter
Silk, Joseph; Wu, Yi-Peng; Pinetti, Elena
If primordial black holes (PBHs) contribute more than 10% of the dark matter (DM) density, their energy density today is of the same order as that of the baryons. Such a cosmic coincidence might hint at a mutual origin for the formation scenario of PBHs and the baryon asymmetry of the Universe. Baryogenesis can be triggered by a sharp transition o…
Deep Search for Decaying Dark Matter with XMM-Newton Blank-Sky Observations
Safdi, Benjamin R.; Foster, Joshua W.; Kongsore, Marius +4 more
Sterile neutrinos with masses in the keV range are well-motivated extensions to the Standard Model that could explain the observed neutrino masses while also making up the dark matter (DM) of the universe. If sterile neutrinos are DM then they may slowly decay into active neutrinos and photons, giving rise to the possibility of their detection thr…
Direct Detection of Hawking Radiation from Asteroid-Mass Primordial Black Holes
Profumo, Stefano; Coogan, Adam; Morrison, Logan
Light, asteroid-mass primordial black holes, with lifetimes in the range between hundreds to several millions times the age of the Universe, are well-motivated candidates for the cosmological dark matter. Using archival COMPTEL data, we improve over current constraints on the allowed parameter space of primordial black holes as dark matter by stud…
Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars
Buschmann, Malte; Safdi, Benjamin R.; Dessert, Christopher +1 more
Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their feeble interactions with matter, and subsequently convert into x rays in the magnetic fields surrounding the stars. We show that a recently discovered excess of hard x-ray emission in the 2-8 keV energy range from the nearby magnificent seven is…
Sensor Noise in LISA Pathfinder: In-Flight Performance of the Optical Test Mass Readout
Mendes, L.; Russano, G.; Sanjuan, J. +85 more
We report on the first subpicometer interferometer flown in space. It was part of ESA's Laser Interferometer Space Antenna (LISA) Pathfinder mission and performed the fundamental measurement of the positional and angular motion of two free-falling test masses. The interferometer worked immediately, stably, and reliably from switch on until the end…
Galactic Potential and Dark Matter Density from Angular Stellar Accelerations
Buschmann, Malte; Safdi, Benjamin R.; Schutz, Katelin
We present an approach to measure the Milky Way (MW) potential using the angular accelerations of stars in aggregate as measured by astrometric surveys like Gaia. Accelerations directly probe the gradient of the MW potential, as opposed to indirect methods using, e.g., stellar velocities. We show that end-of-mission Gaia stellar acceleration data …
Magnetic Topology of Actively Evolving and Passively Convecting Structures in the Turbulent Solar Wind
Chapman, S. C.; Hnat, B.; Watkins, N. W.
Multipoint in situ observations of the solar wind are used to identify the magnetic topology and current density of turbulent structures. We find that at least 35% of all structures are both actively evolving and carrying the strongest currents, actively dissipating, and heating the plasma. These structures are comprised of ∼1 /5 3D plasmoids, ∼3 …
Neutrino and Positron Constraints on Spinning Primordial Black Hole Dark Matter
Ray, Anupam; Laha, Ranjan; Dasgupta, Basudeb
Primordial black holes can have substantial spin—a fundamental property that has a strong effect on its evaporation rate. We conduct a comprehensive study of the detectability of primordial black holes with non-negligible spin, via the searches for the neutrinos and positrons in the MeV energy range. Diffuse supernova neutrino background searches …
Sign of Hard-X-Ray Pulsation from the γ -Ray Binary System LS 5039
Takahashi, T.; Enoto, T.; Makishima, K. +3 more
To understand the nature of the brightest γ -ray binary system LS 5039, hard x-ray data of the object, taken with the Suzaku and NuSTAR observatories in 2007 and 2016, respectively, were analyzed. The two data sets jointly gave tentative evidence for a hard x-ray periodicity, with a period of ∼9 s and a period increase rate by ∼3 ×10-10…
First Results on Dark Matter Substructure from Astrometric Weak Lensing
Van Tilburg, Ken; Weiner, Neal; Taki, Anna-Maria +1 more
Low-mass structures of dark matter (DM) are expected to be entirely devoid of light-emitting regions and baryons. Precisely because of this lack of baryonic feedback, small-scale substructures of the Milky Way are a relatively pristine testing ground for discovering aspects of DM microphysics and primordial fluctuations on subgalactic scales. In t…