# Neutron Star Interior Composition Explorer X-ray Timing of the Radio and Gamma-ray Quiet Pulsars PSR J1412+7922 AND PSR J1849-0001

## TL;DR

This paper presents detailed X-ray timing and spectral analyses of two pulsars, PSR J1412+7922 and PSR J1849-0001, using NICER, improving ephemerides and enabling gravitational wave search constraints.

## Contribution

The study provides the first refined timing and spectral data for these pulsars, enhancing gravitational wave search sensitivity and understanding of their emission properties.

## Key findings

- Improved pulse ephemerides for both pulsars.
- Spectral fits consistent with blackbody and power-law models.
- Constraints on neutron star deformation and oscillation from LIGO data.

## Abstract

We present new timing and spectral analyses of PSR J1412+7922 (Calvera) and PSR J1849-0001, which are only seen as pulsars in X-rays, based on observations conducted with the Neutron Star Interior Composition Explorer (NICER). We obtain updated and substantially improved pulse ephemerides compared to previous X-ray studies, as well as spectra that can be well-fit by simple blackbodies and/or a power law. Our refined timing measurements enable deeper searches for pulsations at other wavelengths and sensitive targeted searches by LIGO/Virgo for continuous gravitational waves from these neutron stars. Using the sensitivity of LIGO's first observing run, we estimate constraints that a gravitational wave search of these pulsars would obtain on the size of their mass deformation and r-mode fluid oscillation.