Inferring pulsar periods from synchro-curvature spectra

TL;DR

This study explores whether pulsar spectral energy distributions can reveal their spin periods, enabling indirect estimation of pulsar timing properties from high-energy emission spectra, especially for unidentified gamma-ray sources.

Contribution

The paper demonstrates that synchro-curvature spectra can constrain pulsar periods within an order of magnitude in most cases, aiding blind searches for pulsars.

Findings

In 8 out of 13 cases, the period is constrained within a factor of ten.

Spectral modeling can provide period estimates even without direct timing measurements.

Degeneracy occurs in some cases, preventing period constraints.

Abstract

The period and the period derivative of a pulsar are critical magnitudes for defining the properties of the magnetospheric size and plasma dynamics. The pulsar light cylinder, the magnetic field intensity nearby it, and the curvature radius all depend on these timing properties, and shape the observed high-energy synchro-curvature emission. Therefore, the radiative properties of pulsars are inextricably linked to them. This fact poses the question of how well does a given pulsar's spectral energy distribution embeds information of the timing parameters, and if so, whether we can deduce them if they have not been measured directly. This is relevant to possibly constrain the timing properties of potential pulsar candidates among unidentified $\gamma$-ray sources. We consider well-measured pulsar spectra blinding us from the knowledge of their timing properties, and address this question by using our radiative synchro-curvature model that was proven able to fit the observed spectra of the pulsar population. We find that in the majority of the cases studied (8/13), the spin period is constrained within a range of about one order of magnitude, within which the real period lies. In the other cases, there is degeneracy and no period range can be constrained. This can be used to facilitate the blind search of pulsed signals.