The Andromeda galaxy is the closest spiral galaxy to us. It harbors a massive dark matter halo which may span up to ∼600 kpc across and comprises ∼90% of the galaxy’s total mass. This halo size translates into a large diameter of 42 degrees on the sky for an M31–Milky Way distance of 785 kpc, but its presumably low surface brightness makes it…

Very light axions are a generic prediction of string compactifications. If cosmic strings associated with these axions were produced in the early universe, they quickly approach a so-called scaling solution, such that strings persist in the sky today.  I will present some remarkable signals of such strings coupled…

There is currently a (possible) tension between various measurements of the Hubble expansion rate. I will give a recap of this issue, and describe  how we use the Cosmic Microwave Background to infer the local expansion rate. I will explain what assumptions we usually make about the cosmological model in doing so,…

Motivated by theories of neutral naturalness, I will argue that Mirror Stars are a generic possibility in any hidden sector with analogues of Standard Model electromagnetism and nuclear physics. I will show that if there exists a tiny kinetic mixing between the dark and SM photon, Mirror Stars capture SM matter from the interstellar medium,…

One generic scenario for the dark matter of our universe is that it resides in a hidden sector: it talks to other dark fields more strongly than it talks to the Standard Model.  I'll discuss some minimal cosmological origin scenarios for this class of models and explore their consequences for the observability of…

This talk will follow the discussions found in https://arxiv.org/abs/1711.04773 and https://arxiv.org/abs/1902.04082. We will discuss the cosmological implications of the Co-Decaying Dark Matter Model--a recently…

Functional methods, in particular efficient reorganization of the one-loop effective action, have recently made a reappearance in simplifying the problem of computing matching and running effects in Lorentz-invariant effective field theories (EFTs) such as the Standard Model Effective Field Theory. This has lead to…

We perform high resolution simulations in a scenario where the Peccei-Quinn (PQ) symmetry is broken after inflation starting at the epoch before the PQ phase transition and ending at matter-radiation equality. We characterize the spectrum of primordial perturbations that are generated and comment on implications for efforts to detect axion dark…

Conventionally, the main focus for the cosmic evolution of our universe has been on descriptions in terms of particles: dark matter (DM) as massive particle, and dark radiation, if existing at all, in the form of massless or very light particle. In this talk, I will discuss a scenario where conformal field theory (CFT) plays a crucial role in…

Axion and Axion-like particles are fascinating dark matter candidates and a great effort has been devoted to their study, both theoretically and experimentally. 

In this talk I will discuss two different astrophysical searches. The first one consists in looking with radio telescopes for the spontaneous…

Recent work has introduced a correspondence between jets and natural languages. In this talk, I will review how machine learning, with this natural language processing point of view, is changing the way we are thinking about jets. First, I will describe a very effective model for classification and regression tasks…

In the next decade, improvements in the CMB and Large Scale Structure (LSS) measurements will make the universe an excellent laboratory for neutrino physics. Besides knowing the sum of neutrino masses, we can better answer questions about neutrino properties, such as how long the SM neutrinos can live? In this talk,…

The Milky Way halo is the brightest source of dark matter (DM) annihilation on the sky. Indeed, the strength of the Galactic dark matter signal can be greater than that expected from dwarf galaxies even in regions away from the Inner Galaxy. In this talk, I will demonstrate the promise of the Milky Way halo, until now less focused on in the…

The properties of the smallest gravitationally-bound dark matter structures can be affected by non-trivial particle physics within the dark sector, and thus could provide the first hints of the non-gravitational interactions of dark matter. As our knowledge of Galactic stellar kinematics grows, we are discovering streams and debris consistent…

The most pressing fine-tuning puzzles of the Standard Model — the cosmological constant and weak hierarchy problems, as well as the Higgs metastability —  can all be understood as problems of near criticality. I will present a natural selection mechanism based on search optimization on the string landscape. The…

It has been recently pointed out that variable weak gravitational lensing effects on the motion of background stars can be used to probe nonluminous structures inside the Milky Way halo. I will describe one possible detection strategy targeting collapsed dark matter structures in the mass range from million to…

The observed flattening of rotation curves is usually considered strong evidence for the existence of dark matter on galactic scales.   However, observations such as the Baryonic Tully-Fisher Relation and the Radial Acceleration Relation suggest that the observed dynamics in galaxies are strongly correlated with the distribution of baryonic…

Detecting light dark matter that interacts weakly with electromagnetism has recently become one of the benchmark goals of near-term and futuristic direct detection experiments. In this talk, I will discuss an alternative approach to directly detecting such models below the GeV-scale, leveraging on the recent…

I discuss ways in which we might make very precise measurements of the dark matter in the Milky Way using kinematic and composition data on stars from the ESA Gaia Mission and spectroscopic surveys like SDSS-IV and -V. I will show two methods that outperform traditional methods (eg, using the Jeans equations), one…

Pulsars act as accurate clocks, sensitive to gravitational redshift and acceleration induced by transiting clumps of matter. We study the sensitivity of pulsar timing arrays (PTAs) to single transiting compact objects, focusing on primordial black holes and compact subhalos in the mass range from 10−12 Msun  to well above 100 M sun. We find…