Advanced localization of massive black hole coalescences with LISA

Understand

The coalescence of massive black holes is one of the primary sources of gravitational waves (GWs) for LISA.

• Measurements of the GWs can localize the source on the sky to an ellipse with a major axis of a few tens of arcminutes to a few degrees, depending on source redshift, and a minor axis which is 2--4 times smaller.
• The distance (and thus an approximate redshift) can be determined to better than a per cent for the closest sources we consider, although weak lensing degrades this performance.
• It will be of great interest to search this three-dimensional `pixel' for an electromagnetic counterpart to the GW event.