This blog is to promote discussion of the science opportunities that will be realized by a future NASA gravitational-wave observatory. Such an observatory was recently ranked among the highest science priorities for this decade by the US astronomy and astrophysics community (New Worlds New Horizons page; or see the final report). The ultimate form of the mission may resemble the well-studied LISA concept, or a variant the European Space Agency’s eLISA (http://www.elisa-ngo.org) concept, and may be pursued as a joint project of NASA, ESA and/or other partners.
Through any formation such a mission will open our ears to the superlative world of the millihertz gravitational-wave sky. We expect the sky to be populated by signals from the most energetic events since the Big Bang, mergers of massive black holes, with multitudinous signals from hard-to-see binary stars across our galaxy, and signals from compact stars being swallowed up by massive black holes in the dark hearts of of galaxies. We may also find objects not yet imagined.
In this blog we explore this coming era of astronomy, where these new measurements will enhance the knowledge of the Universe we have so far gained primarily by observing light. In this way, we will survey the cosmological structure formation and assembly process which led the present day population of galaxies. We will quantitatively probe the structure of distant galactic cores, and we will better understand the stellar populations in our own galaxy. We may even learn something we don’t yet know about the fundamental physics and the basic properties of the Universe.