# X-ray Timing Observations of PSR J1930+1852 in the Crab-like SNR G54.1+0.3

## TL;DR

This paper reports detailed X-ray timing and spectral observations of the young pulsar PSR J1930+1852, revealing its timing noise, pulse profile, and spectral properties, confirming its similarity to Crab-like pulsars.

## Contribution

It provides an updated timing ephemeris over six years, characterizes the pulse profile and spectrum, and discusses timing irregularities such as noise and glitches.

## Key findings

- Significant timing variability and possible glitches observed.
- High pulsed fraction with broad, asymmetric pulse profile.
- Spectral analysis shows a hard power-law spectrum with photon index ~1.2.

## Abstract

We present new X-ray timing and spectral observations of PSR J1930+1852, the young energetic pulsar at the center of the non-thermal supernova remnant G54.1+0.3. Using data obtained with the Rossi X-ray Timing Explorer and Chandra X-ray observatories we have derived an updated timing ephemeris of the 136 ms pulsar spanning 6 years. During this interval, however, the period evolution shows significant variability from the best fit constant spin-down rate of $\dot P = 7.5112(6) \times 10^{-13}$ s s$^{-1}$, suggesting strong timing noise and/or glitch activity. The X-ray emission is highly pulsed ($71\pm5%$ modulation) and is characterized by an asymmetric, broad profile ($\sim 70%$ duty cycle) which is nearly twice the radio width. The spectrum of the pulsed emission is well fitted with an absorbed power law of photon index $\Gamma = 1.2\pm0.2$; this is marginally harder than that of the unpulsed component. The total 2-10 keV flux of the pulsar is $1.7 \times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$. These results confirm PSR J1930+1852 as a typical Crab-like pulsar.