Search Publications
Reference frames in general relativity and the galactic rotation curves
Frutos-Alfaro, F.; Costa, L. Filipe O.; Natário, José +1 more
The physical interpretation of the exact solutions of the Einstein field equations is, in general, a challenging task, part of the difficulties lying in the significance of the coordinate system. We discuss the extension of the International Astronomical Union (IAU) reference system to the exact theory. It is seen that such an extension, retaining…
Constraints on monopole-dipole potential from tests of gravity
Poddar, Tanmay Kumar; Pachhar, Debashis
An ultralight axion like particle (ALP) can mediate a macroscopic force with long-range monopole-dipole interactions between the Earth and the Sun, if the Earth is treated as a polarized source. Because of the geomagnetic field, there exists an estimated 1042 polarized electrons within the Earth. These electrons, in a polarized state, c…
Tilt-to-length coupling in LISA Pathfinder: Analytical modeling
Hartig, Marie-Sophie; Wanner, Gudrun
Tilt-to-length coupling was the limiting noise source in LISA Pathfinder between 20 and 200 mHz before subtraction in postprocessing. To prevent the adding of sensing noise to the data by the subtraction process, the success of this strategy depended on a previous direct noise reduction by test mass alignment. The exact dependency of the level of …
Freezing in vector dark matter through magnetic dipole interactions
Krnjaic, Gordan; Rocha, Duncan; Sokolenko, Anastasia
We study a simple model of vector dark matter that couples to Standard Model particles via magnetic dipole interactions. In this scenario, the cosmological abundance arises through the freeze-in mechanism and depends on the dipole coupling, the vector mass, and the reheat temperature. To ensure cosmological metastability, the vector must be lighte…
Hubble constant from the cluster-lensed quasar system SDSS J 1004 +4112 : Investigation of the lens model dependence
Oguri, Masamune; Liu, Yuting; Cao, Shuo
As a fundamental parameter for modern cosmology, the Hubble constant H0 is experiencing a serious crisis. In this paper, we explore an independent approach to measure H0 based on the time-delay cosmography with strong gravitational lensing of a quasar by a galaxy cluster. Specifically we focus on the strong lensing system SDS…
Constraining dark matter interactions mediated by a light scalar with white dwarfs
Ramirez-Quezada, Maura E.
Observations of white dwarfs in dark matter-rich environments can provide strong limits on the strength of dark matter interactions. Here we apply the recently improved formalism of the dark matter capture rate in white dwarfs to a general model in which dark matter interacts with the white dwarf ion components via a light scalar mediator. We comp…
Simulating the charging of isolated free-falling masses from TeV to eV energies: Detailed comparison with LISA Pathfinder results
Hollington, D.; Wass, P. J.; Sumner, T. J. +1 more
A model is presented that explains the charging rate of the LISA Pathfinder test masses by the interplanetary cosmic ray environment. The model incorporates particle-tracking from TeV to eV energies using a combination of GEANT4 and a custom low-energy particle generation and tracking code. The electrostatic environment of the test mass is simulat…
Extragalactic CO emission lines in the CMB experiments: A forgotten signal and a foreground
Lagache, Guilaine; Pullen, Anthony R.; Maniyar, Abhishek S. +3 more
High resolution cosmic microwave background (CMB) experiments have allowed us to precisely measure the CMB temperature power spectrum down to very small scales (multipole ℓ∼3000 ). Such measurements at multiple frequencies enable separating the power spectrum of the primary CMB anisotropies with the power spectrum of other signals like CMB lensing…
Invisible dilaton
Brax, Philippe; Valageas, Patrick; Burrage, Clare +1 more
We analyze the dynamics of a light scalar field responsible for the µ term of the Higgs potential and coupled to matter via the Higgs-portal mechanism. We find that this dilaton model is stable under radiative corrections induced by the standard model particle masses. When the background value of the scalar field is stabilized at the minimum…
Calibrating the effective magnitudes of type Ia supernovae with a model-independent method
Li, Zhongmu; Chen, Jing; Hu, Jian +2 more
This research explores the correlation between the absolute magnitude and the redshift of type Ia supernovae (SNe Ia) with a model-independent approach. The Pantheon sample of SNe Ia and strong gravitational lensing systems (SGLS) are used. With the cosmic distance-duality relation (CDDR), the evolution parameter of the magnitude, the light curve …