I am a CNES postdoctoral fellow working at Observatoire de Paris in France. My main research interests include theory and phenomenology of spacetime-symmetry breaking in gravity and cosmology, which I explore using effective-field theory techniques. I am also interested in early-Universe physics, cosmic tensions, and the mathematics of group theory. At Observatoire de Paris I focus on Post-Newtonian theory and the generation of gravitational waves by compact sources in the presence of spacetime-symmetry breaking.

Memberships

• I am co-chair of the Early-Career Scientist working group of the LISA (Light Interferometer Space Antenna) consortium, where I also contribute to the Fundamental Physics and Cosmology working groups.

• I am a member of the Career Opportunities office of GWECS (Gravitational-Wave Early Career Scientists).

Selected Papers

• “Reexamining aspects of spacetime-symmetry breaking with CMB polarization”, Nils A. Nilsson and Christophe Le Poncin-Lafitte, Phys.Rev.D 109 (2024) 1, 015032, arXiv.
• “Spacetime symmetry breaking effects in gravitational-wave generation at the first post-Newtonian order”,Nils A. Nilsson and Christophe Le Poncin-Lafitte, Phys.Rev.D 109 (2024) 2, 024035, arXiv
• “Explicit spacetime-symmetry breaking and the dynamics of primordial fields”, Nils A. Nilsson, Phys.Rev.D 106 (2022) 10, 104036, arXiv
• “3+1 formulation of the standard model extension gravity sector”, Kellie O’Neal-Ault, Quentin G. Bailey, Nils A. Nilsson, Phys.Rev.D 103 (2021) 4, 044010, arXiv
• “Hořava–Lifshitz cosmology in light of new data”, Nils A. Nilsson and Ewa Czuchry, Phys.Dark Univ. 23 (2019) 100253, arXiv

Career timeline

2022 - Present

CNES Postdoctoral Fellow @ SYRTE, Observatoire de Paris, France

2021 - 2022

Postdoc @ the Centre for Quantum Spacetime, Sogang University, Seoul, Korea

2020

Ph.D. in Physical Sciences @ the National Centre for Nuclear Research, Warsaw, Poland

Interests

In my free time, I enjoy rock climbing and board games.