Related papers: Where Are the r-modes? Chandra Observations of Mil…
r-mode oscillations have been shown to have a significant potential to constrain the composition of fast spinning neutron stars. Due to their high rotation rates, millisecond pulsars (MSPs) provide a unique platform to constrain the…
NICER observed several rotation-powered millisecond pulsars to search for or confirm the presence of X-ray pulsations. When broad and sine-like, these pulsations may indicate thermal emission from hot polar caps at the magnetic poles on the…
r-mode astroseismology provides a unique way to study the internal composition of compact stars. Due to their precise timing, recycled millisecond radio pulsars present a particularly promising class of sources. Although their thermal…
We present upper limits on the amplitude of r-mode oscillations, and gravitational-radiation-induced spin-down rates, in low mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by…
(Abridge) We observed the accreting millisecond X-ray pulsars XTE J0929-314 and XTE J1751-305 in their quiescent states using Chandra. From XTE J0929-314 we detected 22 photons (0.3-8 keV) in 24.4 ksec, resulting in a count rate of 9 x…
We present the high-resolution spectrum of the accretion-powered millisecond pulsar XTE J0929-314 during its 2002 outburst, measured using the Low Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The 1.5-25.3…
Pulsating thermal X-ray emission from millisecond pulsars can be used to obtain constraints on the neutron star equation of state, but to date only five such sources have been identified. Of these five millisecond pulsars, only two have…
The puzzling existence of a number of neutron stars that appear to be in the r-mode instability window supports further investigations of the r-mode frequencies, damping times and saturation amplitudes, especially now in light of the much…
We present observations of fields containing eight recently discovered binary millisecond pulsars using the telescopes at MDM Observatory. Optical counterparts to four of these systems are detected, one of which, PSR J2214+3000, is a novel…
We present a model of thermal X-ray emission from hot spots on the surface of a rotating compact star with an unmagnetized light-element atmosphere. An application to ROSAT, Chandra, and XMM-Newton X-ray observations of the nearest known…
We report on spectral and timing observations of the nearest millisecond pulsar J0437-4715 with Chandra. The pulsar spectrum, detected up to 7 keV, cannot be described by a simple one-component model. We suggest that it consists of two…
We present results of targeted searches for signatures of non-radial oscillation modes (such as r- and g-modes) in neutron stars using {\it RXTE} data from several accreting millisecond X-ray pulsars (AMXPs). We search for potentially…
We present a case study for the relevance of the r-mode instability for accreting compact stars. Our estimates are based on approximations that facilitate back-of-the-envelope calculations. We discuss two different cases: 1) For recycled…
We report on an XMM-Newton observation of the accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1) Hz are observed with an RMS pulsed fraction of 14.4(3)%. A precise solution for the P_orb=12487.51(2)s binary system…
We describe the first X-ray observations of binary millisecond pulsars PSRs J0023+0923, J1810+1744, J2215+5135, and J2256-1024. All four are Fermi gamma-ray sources and three are 'black-widow' pulsars, with companions of mass < 0.1 solar…
Millisecond pulsar PSR J0218+4232 shows remarkable high-energy properties: very hard pulsed X-ray emission up to ~10 keV and a likely detection of high-energy gamma-rays (> 100 MeV) with a soft spectrum. The relative phasing of the X-ray…
We present a Chandra X-ray Observatory investigation of the millisecond pulsars (MSPs) in the globular cluster M28 (NGC 6626). In what is one of the deepest X-ray observations of a globular cluster, we firmly detect seven and possibly…
We report on a timing and spectral analysis of the young, high magnetic field rotation-powered pulsar (RPP) B1509-58 using Chandra continuous-clocking mode observation. The pulsar's X-ray light curve can be fit by the two Gaussian…
Until now X-radiation from nine millisecond pulsars has been detected. In the present paper we summarize the observations and show the results of a re-analysis of archival ROSAT data. In addition we present the results of recent…
We report the results of new XMM-Newton observations of the middle-aged ($\sim$10$^5$ yr) radio pulsar PSR J1740+1000 carried out in 2017-2018. These long pointings ($\sim$530 ks) show that the non-thermal emission, well described by a…