Archivio mensile:febbraio 2016

Onde gravitazionali

Nel 1916, appena dopo la formulazione delle equazioni di campo della teoria della relatività generale, Einstein predisse l’esistenza di onde gravitazionali.

Oggi, 11 febbraio 2016, è stata annunciata la prima prova sperimentale dell’esistenza di queste onde e i dettagli sono stati pubblicati dalla rivista americana Physical Review Letters.

Il file pdf dell’articolo (in inglese) può essere scaricato qui
Riportiamo il sommario introduttivo dell’articolo.

Phys. Rev. Lett. 116, 061102 – Published 11 February 2016

Abstract

Observation of Gravitational Waves from a Binary Black Hole Merger

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0 \times {10^{ - 21}}. It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410_{ - 180}^{ + 160} Mpc corresponding to a redshift z=0.09_{ - 0.04}^{ + 0.03}. In the source frame, the initial black hole masses are 36_{ - 4}^{ + 5}M⊙ and 29_{-4}^{+4}M⊙, and the final black hole mass is 62_{-4}^{+4}M⊙, with 3.0_{-0.5}^{+0.5}M⊙{c^2} radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.