# IGR J17062-6143 is an Accreting Millisecond X-ray Pulsar

## TL;DR

This paper reports the discovery of the lowest-frequency accreting millisecond X-ray pulsar, IGR J17062-6143, with pulsations detected at 163.65 Hz, indicating orbital motion and expanding understanding of such systems.

## Contribution

First detection of 163.65 Hz pulsations from IGR J17062-6143, establishing it as the lowest-frequency accreting millisecond X-ray pulsar known.

## Key findings

- Pulsations detected at 163.65 Hz with 4.3 sigma significance.
- Pulsation frequency decreases during observation, indicating orbital motion.
- Orbital period likely shorter than 17 minutes, consistent with AMXP population.

## Abstract

We present the discovery of 163.65 Hz X-ray pulsations from IGR J17062-6143 in the only observation obtained from the source with the Rossi X-ray Timing Explorer. This detection makes IGR J17062-6143 the lowest-frequency accreting millisecond X-ray pulsar presently known. The pulsations are detected in the 2 - 12 keV band with an overall significance of 4.3 sigma, and an observed pulsed amplitude of 5.54 +- 0.67 % (in this band). Both dynamic power spectral and coherent phase timing analysis indicate that the pulsation frequency is decreasing during the 1.2 ks observation in a manner consistent with orbital motion of the neutron star. Because the observation interval is short, we cannot precisely measure the orbital period; however, periods shorter than 17 minutes are excluded at 90 % confidence. For the range of acceptable circular orbits the inferred binary mass function substantially overlaps the observed range for the AMXP population as a whole.