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A maximum likelihood estimate of the parameters of the FRB population

, , , and .
(2021)cite arxiv:2109.06785Comment: 5 pages, 3 figures, Accepted for Publication in the MNRAS Letter.

Abstract

We consider a sample of $82$ non-repeating FRBs detected at Parkes, ASKAP, CHIME and UTMOST each of which operates over a different frequency range and has a different detection criteria. Using simulations, we perform a maximum likelihood analysis to determine the FRB population model which best fits this data. Our analysis shows that models where the pulse scatter broadening increases moderately with redshift ($z$) are preferred over those where this increases very sharply or where scattering is absent. Further, models where the comoving event rate density is constant over $z$ are preferred over those where it follows the cosmological star formation rate. Two models for the host dispersion measure ($DM_host$) distribution (a fixed and a random $DM_host$) are found to predict comparable results. We obtain the best fit parameter values $\alpha=-1.53^+0.29_-0.19$, $E_33=1.55^+0.26_-0.22$ and $\gamma=0.770.24$. Here $\alpha$ is the spectral index, $\gamma$ is the exponent of the Schechter luminosity function and $E_33$ is the mean FRB energy in units of $10^33 \, J$ across $2128 - 2848\; MHz$ in the FRB rest frame.

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