pulsar_spectra: A pulsar flux density catalogue and spectrum fitting repository

Abstract

We present the pulsar_spectra software repository, an open-source pulsar flux density catalogue and automated spectral fitting software that finds the best spectral model and produces publication-quality plots. The python-based software includes features that enable users in the astronomical community to add newly published spectral measurements to the catalogue as they become available. The spectral fitting software is an implementation of the method described in Jankowski et al. (2018, MNRAS, 473, 4436) which uses robust statistical methods to decide on the best-fitting model for individual pulsar spectra. pulsar_spectra is motivated by the need for a centralised repository for pulsar flux density measurements to make published measurements more accessible to the astronomical community and provide a suite of tools for measuring spectra.

Characterizing Pulsars Detected in the Rapid ASKAP Continuum Survey

“…There may be a few cases where the fluctuations due to RISS may be comparable to the deviations from a simple power law, but the prevalence of pulsars in which we see deviations from a simple power law and large residuals from a power-law fit means that RISS alone cannot be responsible. This echoes previous conclusions that a power law is not always a good description of the pulsar spectrum and highlights the low-and high-frequency turnovers that are commonly seen (Maron et al 2000;Lorimer & Kramer 2004;Murphy et al 2017;Swainston et al 2022).…”

“…Combining this with more low-and highfrequency data (TGSS, MWA, and VLASS), we find that a quadratic/broken power law represents a better fit to the spectral shape than a pure power law, revealing that the variation of flux density with frequency in logarithmic space can be nonlinear and high-/low-frequency deviations can be very common. The data presented here can be added to repositories like Swainston et al (2022) and used in more advanced spectral modeling. We present the polarization information of these sources, finding that the estimated fraction is consistent with the ones in the literature.…”

“…We performed a least-squares fit to find the spectral index, assuming a power-law distribution, using the flux densities at 400 MHz (ATNF catalog), 888 MHz (RACS low DR1), and 1400 MHz (ATNF catalog). From a visual examination, we excluded 18 pulsars where the flux densities cannot be modeled by a single power law, since they show nonmonotonic behavior, either from more complex spectral behavior (Bates et al 2013;Swainston et al 2022) or from variability among nonsimultaneous measurements. Figure 6 shows the 18 pulsars in our sample that show nonmonotonic spectral evolution and hence cannot be described by a power law.…”

The AO327 Drift Survey Catalog and Data Release of Pulsar Detections

“…Another possible explanation is that, being a member of a relativistic double neutron star system, PSR B1534+12 has been shown to go through changes in flux density and pulse profile shape caused by geodetic precession (Fonseca et al 2014). To investigate further we use the pulsar_spectra code of Swainston et al (2022), which incorporates a large database of pulsar flux density measurements and finds a best fit by trying a number of spectral models of varying complexity. Our measurement of the flux density of B1534+12 at 327 MHz is 5.6(8) mJy, in good agreement with the pulsar_spectra estimate for the same frequency, 7(1) mJy.…”

The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—II. Survey status, pulsar census, and first pulsar discoveries

“…In general, the measurements of low to moderate-DM pulsars are in better agreement compared to high-DM ones (i.e., DM 50 pc cm −3 ). Further details on the data used for the analysis, and the software description, are available in Swainston et al (2022b).…”