The future of gravitational theories in the era of the gravitational wave astronomy

Abstract

We discuss the future of gravitational theories in the framework of gravitational wave (GW) astronomy after the recent GW detections (the events GW150914, GW151226, GW170104, GW170814, GW170817 and GW170608). In particular, a calculation of the frequency and angular dependent response function that a GW detector would see if massive modes from f(R) theories or scalar tensor gravity (STG) were present, allowing for sources incident from any direction on the sky, is shown. In addition, through separate theoretical results which do not involve the recent GW detections, we show that f(R) theories of gravity having a third massless mode are ultimately ruled out while there is still room for STG having a third (massive or massless) mode and for f(R) theories of gravity having a third massive mode.