Luminosity–duration relation of fast radio bursts

Abstract

Nature of dark energy remains unknown. Especially, to constrain the time variability of the dark-energy, a new, standardisable candle that can reach more distant Universe has been awaited. Here we propose a new distance measure using fast radio bursts (FRBs), which are a new emerging population of ∼ ms time scale radio bursts that can reach high-z in quantity. We show an empirical positive correlation between the time-integrated luminosity (L ν ) and rest-frame intrinsic duration (w int,rest ) of FRBs. The L ν − w int,rest correlation is with a weak strength but statistically very significant, i.e., Pearson coefficient is ∼ 0.5 with p-value of ∼0.038, despite the smallness of the current sample. This correlation can be used to measure intrinsic luminosity of FRBs from the observed w int,rest . By comparing the luminosity with observed flux, we measure luminosity distances to FRBs, and thereby construct the Hubble diagram. This FRB cosmology with the L ν − w int,rest relation has several advantages over SNe Ia, Gamma-Ray Burst (GRB), and well-known FRB dispersion measure (DM)-z cosmology; (i) access to higher redshift Universe beyond the SNe Ia, (ii) high event rate that is ∼ 3 order of magnitude more frequent than GRBs, and (iii) it is free from the uncertainty from intergalactic electron density models, i.e., we can remove the largest uncertainty in the well-debated DM-z cosmology of FRB. Our simulation suggests that the L ν − w int,rest relation provides us with useful constraints on the time variability of the dark energy when the next generation radio telescopes start to find FRBs in quantity.

Luminosity–duration relations and luminosity functions of repeating and non-repeating fast radio bursts

“…The L ν -w int,rest relation is one way to constrain the models. The observed positive correlation between L ν and w int,rest of non-repeating FRBs could favour scenarios which predict the positive correlation with slopes similar to the observed value (Hashimoto et al 2019). The favoured scenarios for non-repeating FRBs are, at least, (i) AGN-jet cloud interaction (e.g., Romero et al 2016), (ii) NS-asteroid collision (e.g., Geng & Huang 2015), and (iii) SN remnant powered by a magnetar (e.g., Lyubarsky 2014), since these scenarios predict a positive correlation between L ν and w int,rest (see Hashimoto et al 2019, for details).…”

“…contrast to the positive correlation found for non-repeating FRBs (Hashimoto et al 2019). The time-integrated luminosity, i.e., a total isotropic energy released by the FRB, and duration are physically different quantities.…”

“…We calculated time-integrated luminosities of FRBs at rest-frame 1.83 GHz by using Eq. 6 in Hashimoto et al (2019). This rest-frame frequency is selected so that the K-correction term in Eq.…”

“…One way to constrain FRB origins is a luminosityduration relation of FRBs. Hashimoto et al (2019) found an unexpected positive correlation between the time-integrated luminosity, L ν , and rest-frame intrinsic duration, w rest,int , for non-repeating FRBs (see Sections 3.1 and 3.2 for exact definitions of L ν and w rest,int , respectively). They argued that physical models which explicitly predict the correlation would be favoured for non-repeating FRBs.…”

Revealing the cosmic reionization history with fast radio bursts in the era of Square Kilometre Array

“…the relation is 0.28 dex in log (w int, rest ) axis. This dispersion is dominated by the observational uncertainties of the currently detected FRBs (Hashimoto et al 2019). Since the observational uncertainties of SKA will be ∼ 2 orders of magnitude smaller than that of currently working radio telescopes such as Parkes, the dispersion around the L ν -w int, rest relation would be significantly reduced from the current measurement of 0.28 dex.…”