The RRATalog: a Galactic census of rotating radio transients

Abstract

Rotating radio transients (RRATs) represent a significant but poorly understood component of the Galactic neutron star population, characterized by sporadic emission first detectable only through single-pulse searches. We present the RRATalog, an up-to-date catalogue of 335 RRATs, and utilize a uniform sample of RRATs discovered in four Parkes telescope surveys to model their Galactic population. Accounting in detail for observational selection effects, we find a radial density profile similar to pulsars, but identify a significantly steeper luminosity function (power-law index $α\simeq -1.3$) than previously assumed. For sources beaming towards Earth, we estimate $34000 \pm 1600$ potentially observable RRATs above a peak luminosity of 30 mJy kpc$^2$. At these high luminosities, the RRAT population is comparable in size to that of canonical pulsars. Consistent with the observed distribution, the underlying period distribution is significantly shifted toward longer periods compared to canonical pulsars, suggesting RRATs represent a more evolved population. We find evidence for a turnover in the luminosity function below 30 mJy kpc$^2$, and predict that the total number of potentially observable RRATs is $\lesssim 70,000$. Applying the Tauris \& Manchester beaming model, we estimate the total Galactic RRAT population to be $\lesssim 500,000$. The implied birth rate of $\lesssim 1.4$ RRATs per century is consistent with the Galactic core-collapse supernova rate, suggesting RRATs can be reconciled with known progenitor rates without requiring a separate evolutionary origin. We provide predictions for RRAT discoveries in ongoing and future surveys.

Figures (10)

• Figure 1: Mollweide projection showing the Galactic distribution of RRATs. The symbols in the legend represent the discovery telescope.
• Figure 2: Histograms showing the distributions of observed quantities for RRATs as a function of dispersion measure (DM), spin period, period derivative ($\dot{P}$) and burst rate (${\cal B})$. These distributions have not been corrected for observational selection.
• Figure 3: Scatter diagram showing period versus dispersion measure distribution for the sample. Unlike the sample of pulsars, there appears to be no significant observational selection against short period, high DM RRATs.
• Figure 4: Observed distribution of intrinsic pulse widths and spin periods for the 91 RRATs with measured periods. The black stars correspond to the intrinsic pulse widths derived from observations at 1400 MHz while the red dots correspond to the observations at 350 MHz. The black line shows the fit as described in Eq. \ref{['eq:p_w']} with 1$\sigma$ error bars as the blue shaded region.
• Figure 5: The $P-\dot{\text{P}}$ diagram showing pulsars (blue dots) and RRATs (orange triangles). The dashed lines depict constant magnetic field and the dotted lines show constant characteristic age. The death line is calculated using Eq. 13 from 1992AA...254..198B.