Colpi, Monica Danzmann, Karsten Hewitson, Martin Jetzer, Philippe Nelemans, Gijs Petiteau, Antoine Shoemaker, David Sopuerta, Carlos Stebbins, Robin Tanvir, Nial
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The Laser Interferometer Space Antenna (LISA) is the first scientific endeavour to detect and study gravitational waves from space. LISA will survey the sky for Gravitational Waves in the 0.1 mHz to 1 Hz frequency band which will enable the study of a vast number of objects ranging from Galactic binaries and stellar mass black holes in the Milky Wa...

Du, Xiaolong Marsh, David J. E. Escudero, Miguel Benson, Andrew Blas, Diego Pooni, Charis Kaur Fairbairn, Malcolm

Solitons are observed to form in simulations of dark matter (DM) halos consisting of bosonic fields. We use the extended Press-Schechter formalism to compute the mass function of solitons, assuming various forms for the relationship between halo mass and soliton mass. We further provide a new calculation of the rate of soliton major mergers. Solito...

Escudero, Miguel

Cosmological structure formation simulations of ultralight axion-like dark matter have shown that an axion star forms at the center of every dark matter halo in the Universe. These axion stars would then form in large numbers during the dark ages, $z \lesssim 70$. Axion stars would represent the densest axion environments in the Universe, and as su...

Escudero, Miguel Pooni, Charis Kaur Fairbairn, Malcolm Blas, Diego Du, Xiaolong Marsh, David J. E.

If dark matter is composed of axions, then axion stars form in the cores of dark matter halos. These stars are unstable above a critical mass, decaying to radio photons that heat the intergalactic medium, offering a new channel for axion indirect detection. We recently provided the first accurate calculation of the axion decay rate due to axion sta...

Ferreira, Ricardo Z. Notari, Alessio Pujolàs, Oriol Rompineve, Fabrizio

Unstable domain wall (DW) networks in the early universe are cosmologically viable and can emit a large amount of gravitational waves (GW) before annihilating. As such, they provide an interpretation for the recent signal reported by Pulsar Timing Array (PTA) collaborations. A related important question is whether such a scenario also leads to sign...

Ghiglieri, J. Laine, M. Schütte-Engel, J. Speranza, E.

The thermal plasma filling the early universe generated a stochastic gravitational wave background that peaks in the microwave frequency range today. If the graviton production rate is expressed as a series in a fine-structure constant, $\alpha$, and the temperature over the Planck mass, $T^2_{ } / m_{\rm pl}^2$, then the lowest-order contributions...

Ellis, John Fairbairn, Malcolm Hütsi, Gert Raidal, Juhan Urrutia, Juan Vaskonen, Ville Veermäe, Hardi

The NANOGrav Collaboration has recently announced evidence for nHz gravitational waves (GWs), in the form of a Hellings-Downs angular correlation in the common-spectrum process that had been observed previously by them and other Pulsar Timing Arrays (PTAs). We analyze the possibility that these GWs originate from binary supermassive black holes (SM...

Boudon, Alexis Brax, Philippe Valageas, Patrick Wong, Leong Khim

We investigate the imprints of accretion and dynamical friction on the gravitational-wave signals emitted by binary black holes embedded in a scalar dark matter cloud. As a key feature in this work, we focus on scalar fields with a repulsive self-interaction that balances against the self-gravity of the cloud. To a first approximation, the phase of...

García, Raquel Galazo Brax, Philippe Valageas, Patrick

We study the formation and evolution of solitons supported by repulsive self-interactions inside extended halos, for scalar-field dark matter scenarios. We focus on the semiclassical regime where the quantum pressure is typically much smaller than the self-interactions. We present numerical simulations, with initial conditions where the halo is des...

Harigaya, Keisuke Wang, Isaac R.

Space-time parity can solve the strong CP problem and introduces a spontaneously broken $SU(2)_R$ gauge symmetry. We investigate the possibility of baryogenesis from a first-order $SU(2)_R$ phase transition similar to electroweak baryogenesis. We consider a model with the minimal Higgs content, for which the strong CP problem is indeed solved witho...