We propose a novel method to examine whether Galactic double neutron star
binaries are formed in the LISA band. In our method, we assign an effective
time fraction Ï„ to each double neutron star binary detected by LISA. This
fraction is given as a function of the observed orbital period and eccentricity
and should be uniformly distributed in the absence of in-band binary formation.
Applying statistical techniques such as the Kolmogorov-Smirnov test to the
actual list of Ï„, we can inspect the signature of the in-band binary
formation. We discuss the prospects of this method, paying close attention to
the available sample number of Galactic double neutron star binaries around
1mHz.Comment: 9 pages, 3 figure