Gravitational waves from galaxy encounters

Abstract

We discuss the emission of gravitational radiation produced in encounters of dark matter galactic halos. To this aim we perform a number of numerical simulations of typical galaxy mergers, computing the associated gravitational radiation waveforms as well as the energy released in the processes. Our simulations yield dimensionless gravitational wave amplitudes of the order of 10 ÿ13 and gravitational wave frequencies of the order of 10 ÿ16 Hz, when the galaxies are located at a distance of 10 Mpc. These values are of the same order as those arising in the gravitational radiation originated by strong variations of the gravitational field in the early Universe, and therefore, such gravitational waves cannot be directly observed by ground-based detectors. We discuss the feasibility of an indirect detection by means of the B-mode polarization of the cosmic microwave background (CMB) induced by such waves. Our results show that the gravitational waves from encounters of dark matter galactic halos leave much too small an imprint on the CMB polarization to be actually observed with ongoing and future missions.

galapagos-c: analysis of galaxy morphologies using high-performance computing methods

“…Motions of galaxies through the intra-cluster medium (ICM) at high velocities induce ram-pressure (∼ ρν 2 ) on the gas in a galaxy [e.g. Quilis et al, 2000]. In order to affect the contained gas, the rampressure must be strong enough to overcome the potentially existing dark matter halo and the galactic potential well.…”