We compare the dispersion measure (DM) statistics of FRBs detected by the ASKAP and Parkes radio telescopes. We jointly model their DM distributions, exploiting the fact that the telescopes have different survey fluence limits but likely sample the same underlying population. After accounting for the effects of instrumental temporal and spectral resolution of each sample, we find that a fit between the modelled and observed DM distribution, using identical population parameters, provides a good fit to both distributions. Assuming a one-to-one mapping between DM and redshift for an homogeneous intergalactic medium (IGM), we determine the best-fit parameters of the population spectral index, $\hatα$, and the power-law index of the burst energy distribution, $\hatγ$, for different redshift evolutionary models. Whilst the overall best-fit model yields $\hatα=2.2_{-1.0}^{+0.7}$ and $\hatγ=2.0_{-0.1}^{+0.3}$, for a strong redshift evolutionary model, when we admit the further constraint of $α=1.5$ we favour the best fit $\hatγ=1.5 \pm 0.2$ and the case of no redshift evolution. Moreover, we find no evidence that the FRB population evolves faster than linearly with respect to the star formation rate over the DM (redshift) range for the sampled population.
Fast radio bursts appear to be cosmological signals whose frequency-time structure provides a dispersion measure. The dispersion measure is a convolution of the cosmic distance element and the electron density, and contains the possibility of using these events as new cosmological distance measures. We explore the challenges of extracting the distance in a robust manner, and give quantitative estimates for the systematics control needed for fast radio bursts to become a competitive distance probe. The methodology can also be applied to assessing their use for mapping electron density fluctuati…
Stellar coronae have been invoked to explain the apparently extragalactic dispersion measures observed in fast radio bursts. This paper demonstrates that the suggested plasma densities would lead to deviations from the standard dispersion curve that are inconsistent with the data. The problem is then turned around and higher-order dispersion terms are connected to the moments of the density distribution along the line of sight. The deviations quantified in three observed bursts are analysed and a lower limit on the maximum electron density is obtained in one case, although with considerable un…
Fast radio burst (FRB) discoveries are occurring rapidly, with thousands expected from upcoming surveys. The dispersion measures (DM) observed for FRB include important information on cosmological distances and the ionization state of the universe from the redshift of emission until today. Rather than considering the DM--redshift relation, we investigate the statistical ensemble of the distribution of dispersion measures. We explore the use of this abundance information, with and without redshift information, to probe helium reionization. Carrying out Monte Carlo simulations of FRB survey samp…
Context: Fast Radio Bursts are transient radio pulses from presumably compact stellar sources of extragalactic origin. With new telescopes detecting multiple events per day, statistical methods are required in order to interpret observations and make inferences regarding astrophysical and cosmological questions. Purpose: We present a method that uses probability estimates of fast radio burst observables to obtain likelihood estimates for the underlying models. Method: Considering models for all regions along the line-of-sight, including intervening galaxies, we perform Monte-Carlo simulations …
Fast radio bursts (FRBs) are millisecond-duration transient signals discovered over the past decade. Here we describe the scientific usefulness of FRBs, consider ongoing work at the Parkes telescope, and examine some relevant search sensitivity and completeness considerations. We also look ahead to the results from ongoing and future planned studies in the field.
It is pointed out that the positional distribution of Fast Radio Bursts (FRBs) shows proximity and clustering around the ecliptic. Their dispersion measure (DM) has a weak (80 percent significance level) correlation with the magnitude of the ecliptic latitude. The so called Perytons, however, show no significant proximity to any one of the three astronomical planes, viz celestial, ecliptic or galactic, although they are closer to the galactic plane.
In less than a decade, fast radio bursts have gone from a single debated curiosity to a diverse extragalactic population with established host galaxies and energy scales. While a wide range of models remain viable, the central engines of FRBs are likely to involve energetic young magnetars, as confirmed by the recent discovery of a Galactic analog to these extragalactic bursts. Here we provide a brief introductory review of fast radio bursts, focusing on the rapid recent progress in observations of these enigmatic events, our understanding of their central engines, and their use as probes of t…
Fast Radio Bursts are millisecond bursts of radio radiation at frequencies of about 1 GHz, recently discovered in pulsar surveys. They have not yet been definitively identified with any other astronomical object or phenomenon. The bursts are strongly dispersed, indicating passage through a high column density of low density plasma. The most economical interpretation is that this is the interglactic medium, indicating that FRB are at "cosmological" distances with redshifts in the range 0.3--1.3. Their inferred brightness temperatures are as high as $10^{37\,\circ}$K, implying coherent emission …
Context: Fast radio bursts are transient radio pulses of extragalactic origin. Their dispersion measure is indicative of the baryon content in the ionized intergalactic medium between the source and the observer. However, inference using unlocalized fast radio bursts is degenerate to the distribution of redshifts of host galaxies. Method: We perform a joint inference of the intergalactic baryon content and the fast radio burst redshift distribution with the use of Bayesian statistics by comparing the likelihood of different models to reproduce the observed statistics in order to infer the most…
Fast Radio Bursts (FRBs) are isolated, $\ms$ radio pulses with dispersion measure (DM) of order $10^3\DMunit$. Galactic candidates for the DM of high latitude bursts detected at $\GHz$ frequencies are easily dismissed. DM from bursts emitted in stellar coronas are limited by free-free absorption and those from HII regions are bounded by the nondetection of associated free-free emission at radio wavelengths. Thus, if astronomical, FRBs are probably extra-galactic. FRB 110220 has a scattering tail of $\sim 5.6\pm 0.1 \ms$. If the electron density fluctuations arise from a turbulent cascade, the …
The detection of six Fast Radio Bursts (FRBs) has recently been reported. FRBs are short duration ($\sim$ 1 ms), highly dispersed radio pulses from astronomical sources. The physical interpretation for the FRBs remains unclear but is thought to involve highly compact objects at cosmological distance. It has been suggested that a fraction of FRBs could be physically associated with gamma-ray bursts (GRBs). Recent radio observations of GRBs have reported the detection of two highly dispersed short duration radio pulses using a 12 m radio telescope at 1.4 GHz. Motivated by this result, we have pe…
We review the potential information that can be gleaned from multi-wavelength and multi-messenger detections of Fast Radio Bursts (FRBs). The primary function of such detections, following FRB localization, will be to reveal the progenitors of FRB events. However, these observations serve a more basic function in host galaxy identification, subsequent redshift measurement, and in disentangling the contributions of various line-of-sight contributions to properties of FRBs measured at radio wavelengths.
Fast radio bursts are extragalactic, sub-millisecond radio impulses of unknown origin [1,2]. Their dispersion measures, which quantify the observed frequency-dependent dispersive delays in terms of free-electron column densities, significantly exceed predictions from models [3] of the Milky Way interstellar medium. The excess dispersions are likely accrued as fast radio bursts propagate through their host galaxies, gaseous galactic halos and the intergalactic medium [4,5]. Despite extensive follow-up observations of the published sample of 72 burst sources [6], only two are observed to repeat …
Fast Radio Bursts (FRBs) are recently discovered extra-galactic radio transients which are now used as novel cosmological probes. We show how the Bursts' Dispersion Measure can model-independently probe the history of Hydrogen reionization. Using a FlexKnot free-form parameterization to reconstruct the reionization history we predict an 11% accuracy constraint on the CMB optical depth, and 4% accuracy on the midpoint of reionization, to be achieved with 100 FRBs originating from redshifts z>5.
We estimate the size of a primordial black hole exploding today via a white hole transition, and the power in the resulting explosion, using a simple model. We point out that Fast Radio Bursts, strong signals with millisecond duration, probably extragalactic and having unknown source, have wavelength not far from the expected size of the exploding hole. We also discuss the possible higher energy components of the signal.
Highly beamed, short-duration electromagnetic bursts could be produced by superconducting cosmic string (SCS) loops oscillating in cosmic magnetic fields. We demonstrated that the basic characteristics of SCS bursts such as the electromagnetic frequency and the energy release could be consistently exhibited in the recently discovered fast radio bursts (FRBs). Moreover, it is first showed that the redshift distribution of the FRBs can also be well accounted for by the SCS burst model. Such agreements between the FRBs and SCS bursts suggest that the FRBs could originate from SCS bursts and thus …
Recent observations of short gamma-ray bursts (SGRBs) suggest that binary neutron star (NS) mergers can create highly magnetised, millisecond NSs. Sharp cut-offs in X-ray afterglow plateaus of some SGRBs hint at the gravitational collapse of these remnant NSs to black holes. The collapse of such `supramassive' NSs also describes the blitzar model, a leading candidate for the progenitors of fast radio bursts (FRBs). The observation of an FRB associated with an SGRB would provide compelling evidence for the blitzar model and the binary NS merger scenario of SGRBs, and lead to interesting constra…
We explore the possibility that Fast Radio Bursts are due to the annihilation of cusps on cosmic string loops. We compute the energy released in the annihilation events in the radio region, the expected event rate, and the time scale of the bursts. We find that the energy and event rates are sufficiently high and the time scale is sufficiently small to explain the current data. We predict how the event rate will change as the resolution of telescopes improves. Since the burst rate depends on the string tension, future data will allow the determination of the tension.
We show that radio bursts from cusps on superconducting strings are linearly polarized, thus, providing a signature that can be used to distinguish them from astrophysical sources. We write the event rate of string-generated radio transients in terms of observational variables, namely, the event duration and flux. Assuming a canonical set of observational parameters, we find that the burst event rate can be quite reasonable, e.g., order ten a year for Grand Unified strings with 100 TeV currents, and a lack of observed radio bursts can potentially place strong constraints on particle physics mo…
Three years ago, the report of a solitary radio burst was thought to be the first discovery of a rare, impulsive event of unknown extragalactic origin (Lorimer et al. 2007). The extragalactic interpretation was based on the swept-frequency nature of the event, which followed the dispersive delay expected from an extragalactic pulse. We report here on the detection of 16 pulses, the bulk of which exhibit a frequency sweep with a shape and magnitude resembling the Lorimer Burst. These new events were detected in a sidelobe of the Parkes Telescope and are of clearly terrestrial origin, with prope…
