A consistent estimate for gravitational wave and electromagnetic transient rates

Abstract

Gravitational wave transients, resulting from the merger of two stellar remnants, are now detectable. The properties and rates of these directly relates to the stellar population which gave rise to their progenitors, and thus to other, electromagnetic transients which result from stellar death. We aim to estimate simultaneously the event rates and delay time distribution of gravitational wave-driven compact object mergers together with the rates of core collapse and thermonuclear supernovae within a single consistent stellar population synthesis paradigm. We combine event delay-time distributions at different metallicities from the Binary Population and Spectral Synthesis (BPASS) models with an analytic model of the volume-averaged cosmic star formation rate density and chemical evolution to determine the volume-averaged rates of each event rate at the current time. We estimate rates in excellent agreement with extant observational constraints on core-collapse supernovae, thermonuclear supernovae and long GRBs. We predict rates for gravitational wave mergers based on the same stellar populations, and find rates consistent with current LIGO estimates. We note that tighter constraints on the rates of these events will be required before it is possible to determine their redshift evolution, progenitor metallicity dependence or constrain uncertain aspects of stellar evolution.

Dependence of gravitational wave transient rates on cosmic star formation and metallicity evolution history

“…We modify our method from Eldridge et al (2019) in two ways. First, to allow for uncertainties in the high redshift cosmic star formation history we adopt a star formation rate 1 http://bpass.auckland.ac.nz density as a function of redshift as follows, ψ(z) = 0.015…”

“…In this expression the value of β determines how quickly the Universe becomes enriched with metals, Z, as a function of redshift z and how broad the metallicity distribution is at each redshift. While in Eldridge et al (2019) we used β = 2 here we allow this exponent to vary from 1 to 6. A higher β means the Universe was more quickly enriched, with a smaller metallicity scatter.…”

“…Langer & Norman 2006;de Mink & Belczynski 2015;Eldridge et al 2019). There has been significant study of the how the uncertainties and assumptions in the stellar population models, especially the natalsupernova kick, affect the rate predictions and the observed double neutron star population (e.g Fryer et al 1998;Wex et al 2000;Dominik et al 2013;Lipunov & Pruzhinskaya ntan032@aucklanduni.ac.nz † j.eldridge@auckland.ac.nz 2014; Abbott et al 2016a;Tauris et al 2017;Belczynski et al 2017;Kruckow et al 2018;Vigna-Gómez et al 2018;Chruslinska et al 2018;Mapelli & Giacobbo 2018;Eldridge et al 2019;Andrews & Mandel 2019). However there are also substantial uncertainties in the star formation history of the Universe and its metallicity evolution which have been largely neglected until recently (Lamberts et al 2018;Chruslinska et al 2019;Mapelli et al 2019;Artale et al 2019;Neijssel et al 2019).…”

“…In this letter we build upon our initial work in Eldridge & Stanway (2016) and Eldridge et al (2019) to investigate how varying the early star formation history and metallicity evolution of Universe affects the predicted event rate of GW transients. We compare this to the changes in the event rates from changing some of the parameters within our stellar population synthesis models.…”

Binary population synthesis models for core-collapse gamma-ray burst progenitors

“…If this process occurs at low metallicity, the secondary can retain the angular momentum gained from mass transfer, and end its life as a rapidly spinning type Ic progenitor -a good candidate for producing a GRB. Eldridge et al (2019b) calculated the volumetric event rate of GRBs as a function of redshift, assuming that they arise solely from a quasi-homogeneous evolution (QHE) pathway (Yoon et al 2006;Cantiello et al 2007), using the BPASS stellar evolution and population synthesis code (Eldridge et al 2017). They found that although QHE stars could account for the observed GRB rate, there are significant uncertainties arising from luminosity function and beaming corrections.…”