Volume 625, May 2019
|Number of page(s)||10|
|Published online||22 May 2019|
The luminosity–volume test for cosmological fast radio bursts
Università di Bologna, Dip. di Fisica & Astronomia DIFA, Via Gobetti 92, Bologna, Italy
2 INAF – Istituto di Radioastronomia, Via Gobetti 92, Bologna, Italy
3 Università degli Studi di Milano-Bicocca, Dip. di Fisica “G. Occhialini”, Piazza della Scienza 3, 20126 Milano, Italy
4 INAF – Osservatorio Astronomico di Brera, Via Bianchi 46, 23807 Merate, Italy
5 INFN – Sezione di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
Accepted: 1 April 2019
We have applied the luminosity–volume test, also known as ⟨V/Vmax⟩, to fast radio bursts (FRBs). We compare the 23 FRBs, recently discovered by ASKAP, with 20 of the FRBs found by Parkes. These samples have different flux limits and correspond to different explored volumes. We put constrains on their redshifts with probability distributions (PDFs) and applied the appropriate cosmological corrections to the spectrum and rate in order to compute the ⟨V/Vmax⟩ for the ASKAP and Parkes samples. For a radio spectrum of FRBs ℱν ∝ ν−1.6, we found ⟨V/Vmax⟩ = 0.68 ± 0.05 for the ASKAP sample, that includes FRBs up to z = 0.72+0.42−0.26, and 0.54 ± 0.04 for Parkes, that extends up to z = 2.1+0.47−0.38. The ASKAP value suggests that the population of FRB progenitors evolves faster than the star formation rate, while the Parkes value is consistent with it. Even a delayed (as a power law or Gaussian) star formation rate cannot reproduce the ⟨V/Vmax⟩ of both samples. If FRBs do not evolve in luminosity, the ⟨V/Vmax⟩ values of ASKAP and Parkes sample are consistent with a population of progenitors whose density strongly evolves with redshift as ∼z2.8 up to z ∼ 0.7.
Key words: methods: statistical / radio continuum: general
© ESO 2019
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