Superradiant instabilities may create clouds of ultralight bosons around black holes, forming so-called “gravitational atoms.” It was recently shown that the presence of a binary companion can induce resonant transitions between a cloud's bound states. When these transitions backreact on the binary's orbit, they lead to qualitatively distinct signatures in the gravitational waveform that can...
We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a new gauge field (dark photon) or a...
We investigate Hawking evaporation of a population of primordial black holes (PBHs) prior to Big Bang Nucleosynthesis (BBN) as a mechanism to achieve asymmetric reheating of two sectors coupled solely by gravity. While the visible sector is reheated by the inflaton or a modulus, the dark sector is reheated by PBHs. Compared to inflationary or modular reheating of both sectors, there are two...
Primordial Black Holes (PBH) in the intermediate mass range can be seeds for supermassive black holes and recent LIGO detections of black hole mergers in the mass gap suggest PBH progenitors. I present a novel constraint on the PBH mass fraction spanning PBH masses of ~10-10^6 solar masses from thermal equilibrium considerations. A population of PBH in the central region of the dwarf galaxy...
Gravitational waves provide a unique method of testing theories with extended gauge symmetries. In particular, spontaneous symmetry breaking can lead to a detectable stochastic gravitational wave background generated by cosmic strings and first order phase transitions in the early universe. I will discuss the unique gravitational wave signature of a dark matter model with gauged baryon and...
Unusual masses of black holes being discovered by gravitational wave experiments pose fundamental questions about their origin. More interestingly, black holes with masses smaller than the Chandrasekhar limit (∼ 1.4 solar mass) are essentially impossible to produce through any standard stellar evolution. Primordial black holes, with fine-tuned parameters, and with no compelling formation...
Black holes are never isolated in realistic astrophysical environments; instead, they are often perturbed by complicated external tidal fields. How does a black hole respond to these tidal perturbations? In this talk, I will discuss both the conservative and dissipative responses of the Kerr black hole to a weak and adiabatic gravitational field. The former describes how the black hole would...
Black hole superradiance is a powerful probe of light, weakly-coupled hidden sector particles. Particles with a Compton wavelength comparable to the black hole’s radius lead to an instability, extracting mass and angular momentum from the black hole. Many ultralight candidates, such as axions, generically have self-interactions that can influence the evolution of the superradiant instability....
We describe a new production mechanism of particle dark matter, which hinges on momentum filtering during a first-order cosmological phase transition. We then show that this mechanism can be modified to provide a new production mechanism of primordial black holes, which have not yet been observed but could solve a number of problems in cosmology.
Gravitational microlensing constrains the abundance of massive compact objects in the Galactic halo. Historical studies (MACHO, EROS, OGLE, MOA) have excluded objects lighter than 10 solar masses as a major component of Galactic dark matter. The detection of coalescences of heavier black holes by LIGO/Virgo has rekindled interest in dark matter as compact objects. The effectiveness of previous...
To date, the only direct evidence of gravitational waves (GWs) comes from the detection of merging black holes and neutron stars by the LIGO and Virgo detectors. Observations of these mergers have provided a wealth of astrophysical information as well as constraining theories of modified gravity. However, no convincing signs of new physics have yet been found in GW data. In this talk I will...
Primordial black holes hypothetically generated in the first instants of life of the Universe are potential dark matter (DM) candidates. Focusing on Primordial black holes masses in the range [5×10^{14}-5×10^{15}]g, we point out that the neutrinos emitted by PBHs evaporation can interact through the coherent elastic neutrino nucleus scattering producing an observable signal in multi-ton Dark...
