Search Publications
Beyond the Required LISA Free-Fall Performance: New LISA Pathfinder Results down to 20 µ Hz
Mendes, L.; Russano, G.; Lloro, I. +75 more
In the months since the publication of the first results, the noise performance of LISA Pathfinder has improved because of reduced Brownian noise due to the continued decrease in pressure around the test masses, from a better correction of noninertial effects, and from a better calibration of the electrostatic force actuation. In addition, the ava…
MICROSCOPE Mission: First Constraints on the Violation of the Weak Equivalence Principle by a Light Scalar Dilaton
Bergé, Joel; Pernot-Borràs, Martin; Uzan, Jean-Philippe +3 more
The existence of a light or massive scalar field with a coupling to matter weaker than gravitational strength is a possible source of violation of the weak equivalence principle. We use the first results on the Eötvös parameter by the MICROSCOPE experiment to set new constraints on such scalar fields. For a massive scalar field of mass smaller tha…
Testing General Relativity with the Reflection Spectrum of the Supermassive Black Hole in 1H0707-495
Cao, Zheng; Bambi, Cosimo; Nampalliwar, Sourabh +2 more
Recently, we have extended the x-ray reflection model relxill to test the spacetime metric in the strong gravitational field of astrophysical black holes. In the present Letter, we employ this extended model to analyze XMM-Newton, NuSTAR, and Swift data of the supermassive black hole in 1H0707-495 and test deviations from a Kerr metric parametrize…
Constraining a Thin Dark Matter Disk with G a i a
Safdi, Benjamin R.; Schutz, Katelin; Lin, Tongyan +1 more
If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy that is coplanar with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including periodic comet impacts. Using the first data release from the Gaia space observatory, we sea…
Compressible Magnetohydrodynamic Turbulence in the Earth's Magnetosheath: Estimation of the Energy Cascade Rate Using in situ Spacecraft Data
Sahraoui, F.; Huang, S. Y.; Hadid, L. Z. +1 more
The first estimation of the energy cascade rate |ɛC| of magnetosheath turbulence is obtained using the Cluster and THEMIS spacecraft data and an exact law of compressible isothermal magnetohydrodynamics turbulence. The mean value of |ɛC| is found to be close to 10-13 J m-3 s-1 , at least 2 ord…
Fully Kinetic Simulation of 3D Kinetic Alfvén Turbulence
Grošelj, Daniel; Mallet, Alfred; Jenko, Frank +1 more
We present results from a three-dimensional particle-in-cell simulation of plasma turbulence, resembling the plasma conditions found at kinetic scales of the solar wind. The spectral properties of the turbulence in the subion range are consistent with theoretical expectations for kinetic Alfvén waves. Furthermore, we calculate the local anisotropy…
Dark Matter Equation of State through Cosmic History
Kopp, Michael; Skordis, Constantinos; Thomas, Daniel B. +1 more
Cold dark matter is a crucial constituent of the current concordance cosmological model. Having a vanishing equation of state (EOS), its energy density scales with the inverse cosmic volume and is thus uniquely described by a single number, its present abundance. We test the inverse cosmic volume law for dark matter (DM) by allowing its EOS to var…
Coherent Structures and Spectral Energy Transfer in Turbulent Plasma: A Space-Filter Approach
Sorriso-Valvo, L.; Retinò, A.; Califano, F. +1 more
Plasma turbulence at scales of the order of the ion inertial length is mediated by several mechanisms, including linear wave damping, magnetic reconnection, the formation and dissipation of thin current sheets, and stochastic heating. It is now understood that the presence of localized coherent structures enhances the dissipation channels and the …
Two-Dimensional Solar Wind Speeds from 6 to 26 Solar Radii in Solar Cycle 24 by Using Fourier Filtering
Moon, Yong-Jae; Song, Donguk; Lee, Harim +5 more
Measurement of the solar wind speed near the Sun is important for understanding the acceleration mechanism of the solar wind. In this Letter, we determine 2D solar wind speeds from 6 to 26 solar radii by applying Fourier motion filters to SOHO/LASCO C3 movies observed from 1999 to 2010. Our method successfully reproduces the original flow speeds i…
Testing the Universality of Free Fall towards Dark Matter with Radio Pulsars
Kramer, Michael; Shao, Lijing; Wex, Norbert
The violation of the weak equivalence principle (EP) in the gravitational field of Earth, described by the Eötvös parameter η⊕ , was recently constrained to the level |η⊕| ≲10-14 by the MICROSCOPE space mission. The Eötvös parameter ηDM, pertaining to the differential couplings of dark matter (DM) and or…