Search Publications
GeV-scale thermal WIMPs: Not even slightly ruled out
Slatyer, Tracy R.; Beacom, John F.; Ng, Kenny C. Y. +1 more
Weakly interacting massive particles (WIMPs) have long reigned as one of the leading classes of dark matter candidates. The observed dark matter abundance can be naturally obtained by freezeout of weak-scale dark matter annihilations in the early Universe. This "thermal WIMP" scenario makes direct predictions for the total annihilation cross secti…
Explaining LIGO's observations via isolated binary evolution with natal kicks
Belczynski, Krzysztof; Holz, Daniel E.; Berti, Emanuele +5 more
We compare binary evolution models with different assumptions about black-hole natal kicks to the first gravitational-wave observations performed by the LIGO detectors. Our comparisons attempt to reconcile merger rate, masses, spins, and spin-orbit misalignments of all current observations with state-of-the-art formation scenarios of binary black …
Dark matter hurricane: Measuring the S1 stream with dark matter detectors
Belokurov, Vasily; Evans, N. Wyn; Myeong, GyuChul +2 more
The recently discovered S1 stream passes through the Solar neighborhood on a low inclination, counterrotating orbit. The progenitor of S1 is a dwarf galaxy with a total mass comparable to the present-day Fornax dwarf spheroidal, so the stream is expected to have a significant DM component. We compute the effects of the S1 stream on WIMP and axion …
Gravitational waves and the polarizations in Hořava gravity after GW170817
Gong, Yungui; Hou, Shaoqi; Papantonopoulos, Eleftherios +1 more
The gravitational waves of Hořava gravity, their polarization states, and their possible observational signatures are discussed. Using the gauge-invariant variable formalism, we find the three polarization modes in Hořava gravity excited by the three physical degrees of freedom contained in this theory. In particular, the scalar degree of freedom …
Astrometric effects of gravitational wave backgrounds with non-Einsteinian polarizations
Gilmore, Gerard; Mihaylov, Deyan P.; Moore, Christopher J. +2 more
The Gaia mission offers a new opportunity to search for the low-frequency gravitational wave background using astrometric measurements. In this paper, the astrometric effect of gravitational waves is reviewed, with a particular focus on the effect of non-Einsteinian gravitational wave polarizations. A stochastic gravitational wave background gener…
Constraining the polarization content of gravitational waves with astrometry
O'Beirne, Logan; Cornish, Neil J.
Gravitational waves perturb the paths of photons, impacting both the time of flight and the arrival direction of light from stars. Pulsar timing arrays can detect gravitational waves by measuring the variations in the time of flight of radio pulses, while astrometry missions such as Gaia can detect gravitational waves from the time-varying changes…
Test of general relativity during the BepiColombo interplanetary cruise to Mercury
Schettino, Giulia; Serra, Daniele; Tommei, Giacomo +1 more
The theory of general relativity first introduced the concept that space-time is curved by the presence of masses. As a consequence, any signal between two sources passing by a massive body is deflected and therefore experiences a transmission time delay with respect to the straight-line propagation. In the parametrized Post-Newtonian formalism—wh…
Effects of a caustic ring of dark matter on the distribution of stars and interstellar gas
Chakrabarty, Sankha S.; Sikivie, Pierre
Caustic rings of dark matter with tricusp cross section were predicted to lie in the galactic disk. Their radii increase on cosmological time scales at a rate of order 1 kpc /Gyr . When a caustic ring passes through the orbit of a star, the orbit is strongly perturbed. We find that a star moving in a nearly circular orbit is first attracted toward…
Astrometric test of the weak equivalence principle
Xie, Yi
Weak equivalence principle (WEP) is, for the first time, tested by astrometry on quasars in the sky measured in two wavelengths. Compared to previous WEP tests based on the Shapiro time delay of massless particles, this one has profound superiority that nearly 1 700 quasars with best measured positions commonly in the optical and radio bands are a…
Gravitational wave effects on astrometric observables
Bini, Donato; Geralico, Andrea
Observational data from the European Space Agency astrometric mission Gaia determining the positions of celestial objects within an accuracy of a few microarcseconds will be soon fully available. Other satellite-based space missions are currently planned to significantly improve such precision in the next years. The data reduction process needs hi…