POLAR measurements of the Crab pulsar

TL;DR

POLAR, a Compton polarimeter on Tiangong-2, successfully detected and analyzed the Crab pulsar's pulse profile, timing, and potential polarization, demonstrating its effective detection capabilities in the 50-500 keV range.

Contribution

This work presents the first results of POLAR's observations of the Crab pulsar, including pulse profile, timing calibration, and polarization measurement potential.

Findings

Significant pulsed signals detected from Crab pulsar.

Pulse profile consistent with other detectors like Fermi/LAT and INTEGRAL.

Accurate timing measurements verified POLAR's timing system.

Abstract

POLAR is a Compton polarimeter sensitive in the 50 to 500 keV energy range. The Crab pulsar is a scientific target for POLAR on board the Chinese space laboratory Tiangong-2 (TG-2). With its large Field of View (FoV), POLAR detected significant pulsed signals from the Crab pulsar which is visible by POLAR in about half of observation time. In this work, we present the preliminary results including the pulse profile, timing and polarization measuring method. First, we show the highly significant pulse profile observed by POLAR which is compared to the results of other detectors including Fermi/LAT and INTEGRAL. And the pulse profile as a function of theta incident angle and as a function of channel number, which indicate that POLAR has a good detection performance, have been showed. Second, we find that the timing of the Crab pulses are accurately measured, which provides a unique verification and calibration to the POLAR timing system. Finally, the potential polarization measurement of the Crab pulsar is also discussed.