scholarly journals The broad X-ray emission of the millisecond pulsar PSR J0437–4715

2017 ◽  
Vol 13 (S337) ◽  
pp. 340-341
Author(s):  
Sebastien Guillot
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Dense Matter ◽  
Conference Proceeding ◽  
Millisecond Pulsar ◽  
X Ray ◽  
Surface Emission ◽  
Spin Period ◽  
Modelling Method ◽  
The Ideal

AbstractThe nearest millisecond pulsar PSR J0437–4715 is the ideal target to constrain the dense matter equation of state using the lightcurve modelling method. Our analysis combining XMM-Newton, NuSTAR, and ROSAT observations removed ambiguities in the spectral modelling of the surface emission from PSR J0437–4715. Furthermore, the NuSTAR observation demonstrated that the non-thermal hard tail emission was pulsed at the pulsar spin period. These features are crucial to model the lightcurve and to measure the radius of the neutron star. This conference proceeding is based on the publication Guillot et al. (2016).

scholarly journals Constraining the Neutron Star Mass–Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-Ray Data Set

2019 ◽  
Vol 887 (1) ◽  
pp. L25 ◽  
Author(s):  
Slavko Bogdanov ◽  
Sebastien Guillot ◽  
Paul S. Ray ◽  
Michael T. Wolff ◽  
Deepto Chakrabarty ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Dense Matter ◽  
Millisecond Pulsar ◽  
Data Set ◽  
X Ray ◽  
Star Mass ◽  
Neutron Star Mass

scholarly journals Thermal X-ray emission identified from the millisecond pulsar PSR J1909–3744

2019 ◽  
Vol 627 ◽  
pp. A141 ◽  
Author(s):  
N. A. Webb ◽  
D. Leahy ◽  
S. Guillot ◽  
N. Baillot d’Etivaux ◽  
D. Barret ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Thermal Emission ◽  
Black Body ◽  
Millisecond Pulsar ◽  
Distance Measurements ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Link Type

Context. 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 well-constrained neutron star masses, which improve the determination of the radius via modelling of the X-ray waveform. Aims. We aim to find other millisecond pulsars that already have well-constrained mass and distance measurements that show pulsed thermal X-ray emission in order to obtain tight constraints on the neutron star equation of state. Methods. The millisecond pulsar PSR J1909–3744 has an accurately determined mass, M = 1.54 ± 0.03 M⊙ (1σ error) and distance, D = 1.07 ± 0.04 kpc. We analysed XMM-Newton data of this 2.95 ms pulsar to identify the nature of the X-ray emission. Results. We show that the X-ray emission from PSR J1909–3744 appears to be dominated by thermal emission from the polar cap. Only a single component model is required to fit the data. The black-body temperature of this emission is $ {kT}=0.26^{0.03}_{0.02} $ keV and we find a 0.2–10 keV un-absorbed flux of 1.1 × 10−14 erg cm−2 s−1 or an un-absorbed luminosity of 1.5 × 1030 erg s−1. Conclusion. Thanks to the previously determined mass and distance constraints of the neutron star PSR J1909–3744, and its predominantly thermal emission, deep observations of this object with future X-ray facilities should provide useful constraints on the neutron star equation of state.

Pulsar demography and neutron star astrophysics

1992 ◽  
Vol 341 (1660) ◽  
pp. 77-92 ◽  
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Dense Matter ◽  
Millisecond Pulsar ◽  
Theoretical Understanding ◽  
Origin And Evolution ◽  
Spin Period ◽  
Statistical Studies ◽  
Pulsar Searches ◽  
The Magnetic Field

Pulsars, in particular, millisecond and binary pulsars offer new and unique tests of physics. The explosive birth of neutron stars and coalescence of binary neutron stars are prime targets for planned gravitational wave interferometers. All these applications require a thorough understanding of the statistics of pulsars to reliably estimate detection frequencies and thresholds. There are many aspects of the origin and evolution of neutron stars that benefit from an appreciation of pulsar phenomenology and statistics. Theoretical understanding of the magnetic field evolution of neutron stars is, at the present, poor. Statistical studies continue to play an important role in guiding us empirically in this area. The shortest spin period of a neutron star directly constrains the equation of state of dense matter. The limitations of current millisecond pulsar searches in this regard is thoroughly reviewed. The prospects and problems of searchers for pulsars with periods below a millisecond are reviewed.

scholarly journals X-rays from Radio Millisecond Pulsars

2017 ◽  
Vol 13 (S337) ◽  
pp. 116-119
Author(s):  
Slavko Bogdanov
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Thermal Radiation ◽  
Dense Matter ◽  
X Rays ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Polar Caps ◽  
Galactic Population ◽  
Pulsar Wind

AbstractThe Galactic population of rotation-powered (aka radio) millisecond pulsars (MSPs) exhibits diverse X-ray properties. Energetic MSPs show pulsed non-thermal radiation from their magnetospheres. Eclipsing binary MSPs predominantly have X-ray emission from a pulsar wind driven intra-binary shock. Typical radio MSPs emit X-rays from their heated magnetic polar caps. These thermally emitting MSPs offer the opportunity to place interesting constraints on the long sought after dense matter equation of state, making them important targets of investigation of the recently deployed Neutron Star Interior Composition Explorer (NICER) X-ray mission.

scholarly journals Superburst Oscillations: ocean and crustal modes excited by X-Ray bursts

2017 ◽  
Vol 13 (S337) ◽  
pp. 324-325
Author(s):  
Frank R. N. Chambers ◽  
Anna L. Watts
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
High Frequency ◽  
Dense Matter ◽  
Potential Mechanism ◽  
Pulse Profile ◽  
X Ray ◽  
Neutron Star Mass ◽  
Nuclear Burning ◽  
Good Probe

AbstractSuperburst oscillations are high frequency X-ray variations observed during hours’ long superbursts on accreting neutron stars. We investigate a potential mechanism to explain these observations; a buoyant r-mode, excited in the ocean layers of the star. These modes are affected by ash composition in the ocean so are a good probe of nuclear burning processes. The phenomenon could be used in pulse profile modelling as a way of measuring neutron star mass and radius, and so the dense matter equation of state.

scholarly journals UV and X-ray observations of the neutron star LMXB EXO 0748–676 in its quiescent state

2020 ◽  
Vol 501 (1) ◽  
pp. 1453-1462
Author(s):  
A S Parikh ◽  
N Degenaar ◽  
J V Hernández Santisteban ◽  
R Wijnands ◽  
I Psaradaki ◽  
...  
Keyword(s):  
Neutron Star ◽  
Thermal Emission ◽  
Hubble Space Telescope ◽  
Dense Matter ◽  
Continuum Emission ◽  
Quiescent State ◽  
X Ray ◽  
Low Level ◽  
Low Mass ◽  
Different Origins

ABSTRACT The accretion behaviour in low-mass X-ray binaries (LMXBs) at low luminosities, especially at <1034 erg s−1, is not well known. This is an important regime to study to obtain a complete understanding of the accretion process in LMXBs, and to determine if systems that host neutron stars with accretion-heated crusts can be used probe the physics of dense matter (which requires their quiescent thermal emission to be uncontaminated by residual accretion). Here, we examine ultraviolet (UV) and X-ray data obtained when EXO 0748–676, a crust-cooling source, was in quiescence. Our Hubble Space Telescope spectroscopy observations do not detect the far-UV continuum emission, but do reveal one strong emission line, C iv. The line is relatively broad (≳3500 km s−1), which could indicate that it results from an outflow such as a pulsar wind. By studying several epochs of X-ray and near-UV data obtained with XMM–Newton, we find no clear indication that the emission in the two wavebands is connected. Moreover, the luminosity ratio of LX/LUV ≳ 100 is much higher than that observed from neutron star LMXBs that exhibit low-level accretion in quiescence. Taken together, this suggests that the UV and X-ray emission of EXO 0748–676 may have different origins, and that thermal emission from crust-cooling of the neutron star, rather than ongoing low-level accretion, may be dominating the observed quiescent X-ray flux evolution of this LMXB.

scholarly journals Discovery of accretion-driven pulsations in the prolonged low X-ray luminosity state of the Be/X-ray transient GX 304–1

2018 ◽  
Vol 620 ◽  
pp. L13 ◽  
Author(s):  
A. Rouco Escorial ◽  
J. van den Eijnden ◽  
R. Wijnands
Keyword(s):  
Neutron Star ◽  
Stable State ◽  
Type I ◽  
X Ray ◽  
Monitoring Campaign ◽  
Spin Period ◽  
One Year ◽  
The Many ◽  
Low X ◽  
Star Surface

We present our Swift monitoring campaign of the slowly rotating neutron star Be/X-ray transient GX 304–1 (spin period of ∼275 s) when the source was not in outburst. We found that between its type I outbursts, the source recurrently exhibits a slowly decaying low-luminosity state (with luminosities of 1034 − 35 erg s−1). This behaviour is very similar to what has been observed for another slowly rotating system, GRO J1008–57. For that source, this low-luminosity state has been explained in terms of accretion from a non-ionised (“cold”) accretion disc. Because of the many similarities between the two systems, we suggest that GX 304–1 enters a similar accretion regime between its outbursts. The outburst activity of GX 304–1 ceased in 2016. Our continued monitoring campaign shows that the source is in a quasi-stable low-luminosity state (with luminosities a few factors lower than previously seen) for at least one year now. Using our NuSTAR observation in this state, we found pulsations at the spin period, demonstrating that the X-ray emission is due to accretion of matter onto the neutron star surface. If the accretion geometry during this quasi-stable state is the same as during the cold-disc state, then matter indeed reaches the surface (as predicted) during this later state. We discuss our results in the context of the cold-disc accretion model.

scholarly journals NGC 300 ULX1: A test case for accretion torque theory

2018 ◽  
Vol 620 ◽  
pp. L12 ◽  
Author(s):  
G. Vasilopoulos ◽  
F. Haberl ◽  
S. Carpano ◽  
C. Maitra
Keyword(s):  
Neutron Star ◽  
Test Case ◽  
X Ray ◽  
Spin Period ◽  
Spin Evolution ◽  
Spin Reversal ◽  
Eddington Limit

NGC 300 ULX1 is a newly identified ultra-luminous X-ray pulsar. The system is associated with the supernova impostor SN 2010da that was later classified as a possible supergiant Be X-ray binary. In this work we report on the spin period evolution of the neutron star based on all the currently available X-ray observations of the system. We argue that the X-ray luminosity of the system has remained almost constant since 2010, at a level above ten times the Eddington limit. Moreover, we find evidence that the spin period of the neutron star evolved from ∼126 s down to ∼18 s within a period of about 4 years. We explain this unprecedented spin evolution in terms of the standard accretion torque theory. An intriguing consequence for NGC 300 ULX1 is that a neutron star spin reversal should have occurred a few years after the SN 2010da event.

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