Cosmological Evolution of the Formation Rate of Short Gamma-Ray Bursts with and without Extended Emission

Originating from neutron star–neutron star or star–black hole mergers, short gamma-ray bursts (SGRBs) are the first electromagnetic emitters associated with gravitational waves (GWs). This association makes determination of SGRB formation rate (FR) a critical issue. We determine true FR and its relation to cosmic (SFR). can help in determining expected GW involving small mass mergers. present nonparametric methods for evolutions luminosity function (LF) using SGRBs observed by Swift, without any assumptions. These powerful tools samples, such as our sample 68 SGRBs. combine extended emission (SEE), assuming that both descend same progenitor. To overcome incompleteness introduced redshift measurements we use Kolmogorov–Smirnov (KS) test find flux thresholds yielding sources drawn parent including all sources. Using two subsamples limits 4.57 × 10?7 2.15 erg cm?2 s?1 respective KS p = (1, 0.9), 3? evidence evolution (LE), broken power-law LF significant steepening at L ? 1050 s?1, an decreases monotonically (independent LE thresholds). Thus, may have been more luminous past delayed relative SFR merger scenario.