Search Publications
Exploring the effects of primordial non-Gaussianity at galactic scales
Famaey, Benoit; Ibata, Rodrigo; Stahl, Clément +2 more
While large scale primordial non-Gaussianity is strongly constrained by present-day data, there are no such constraints at Mpc scales. Here we investigate the effect of significant small-scale primordial non-Gaussianity on structure formation and the galaxy formation process with collisionless simulations: specifically, we explore four different t…
Astrometric microlensing of primordial black holes with Gaia
Rentala, Vikram; Verma, Himanshu
The Gaia space telescope allows for unprecedented accuracy for astrometric measurements of stars in the Galaxy. In this work, we explore the sensitivity of Gaia to detect primordial black hole (PBH) dark matter through the distortions that PBHs would create in the apparent trajectories of background stars, an effect known as astrometric microlensi…
A' view of the sunrise: boosting helioscopes with angular information
Frerick, Jonas; Kahlhoefer, Felix; Schmidt-Hoberg, Kai
The Sun may copiously produce hypothetical light particles such as axions or dark photons, a scenario which can be experimentally probed with so-called helioscopes. Here we investigate the impact of the angular and spectral distribution of solar dark photons on the sensitivity of such instruments. For the first time we evaluate this spectral and a…
The morphology of exciting dark matter and the galactic 511 keV signal
Vincent, Aaron C.; Cappiello, Christopher V.; Jafs, Michael
We study the morphology of the 511 keV signal that could be produced by exciting dark matter (XDM) in the Milky Way. In this model, collisions between dark matter particles excite the dark matter to a state that can then decay back to the ground state, releasing an electron-positron pair. These electrons and positrons would then annihilate, produc…
White dwarf mass-radius relation in theories beyond general relativity
Alam, Khursid; Islam, Tousif
We explore the internal structures of the white dwarfs in two different modified theories of gravity: (i) scalar-tensor-vector gravity and (ii) beyond Horndeski theories of G 3 type. The modification of the gravitational force inside the white dwarf results in the modification of the mass and radius of the white dwarf. We use observatio…
Pseudoscalar sterile neutrino self-interactions in light of Planck, SPT and ACT data
Gariazzo, Stefano; Archidiacono, Maria; Hannestad, Steen +4 more
We reassess the viability of a cosmological model including a fourth additional sterile neutrino species that self-interacts through a new pseudoscalar degree of freedom. We perform a series of extensive analyses fitting various combinations of cosmic microwave background (CMB) data from Planck, the Atacama Cosmology Telescope (ACT) and the South …
Introducing the MeVCube concept: a CubeSat for MeV observations
Lucchetta, Giulio; Ackermann, Markus; Berge, David +1 more
Despite the impressive progress achieved both by X-ray and gamma-ray observatories in the last few decades, the energy range between ~ 200 keV and ~ 50 MeV remains poorly explored. COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, 1991-2000), opened the MeV gamma-ray band as a new window to astronomy, performing the first all-sky survey i…
Diffuse x-ray and gamma-ray limits on boson stars that interact with nuclei
Acevedo, Javier F.; Bhoonah, Amit; Bramante, Joseph
Light bosonic dark matter can form gravitationally bound states known as boson stars. In this work, we explore a new signature of these objects interacting with the interstellar medium (ISM). We show how small effective couplings between the bosonic dark matter and the nucleon lead to a potential that accelerates ISM baryons as they transit the bo…
Novel constraints on the particle nature of dark matter from stellar streams
Bovy, Jo; Erkal, Denis; Bertone, Gianfranco +2 more
Tidal streams are highly sensitive to perturbations from passing dark matter (DM) subhalos and thus provide a means of measuring their abundance. In a recent paper, we analyzed the distribution of stars along the GD-1 stream with a combination of data from the Gaia satellite and the Pan-STARRS survey, and we demonstrated that the population of DM …
Exploring the early Universe with Gaia and Theia
Garcia-Bellido, Juan; Murayama, Hitoshi; White, Graham
It has recently been pointed out that Gaia is capable of detecting a stochastic gravitational wave background in the sensitivity band between the frequency of pulsar timing arrays and LISA. We argue that Gaia and Theia have great potential for early universe cosmology, since such a frequency range is ideal for probing phase transitions in asymmetr…