Pulse Phase Variations of the X‐Ray Spectral Features in the Radio‐quiet Neutron Star 1E 1207−5209

2002 ◽  
Vol 581 (2) ◽  
pp. 1280-1285 ◽  
Author(s):  
S. Mereghetti ◽  
A. De Luca ◽  
P. A. Caraveo ◽  
W. Becker ◽  
R. Mignani ◽  
...  
Keyword(s):  
Neutron Star ◽  
Spectral Features ◽  
X Ray ◽  
Pulse Phase ◽  
Phase Variations

scholarly journals The Future X-ray Observations of Pulsars and Isolated Neutron Stars

2000 ◽  
Vol 177 ◽  
pp. 717-720
Author(s):  
Joachim Trümper
Keyword(s):  
Chemical Composition ◽  
Neutron Star ◽  
Neutron Stars ◽  
Spectral Features ◽  
Next Generation ◽  
X Ray ◽  
Future Goals ◽  
Single Neutron ◽  
Higher Sensitivity

AbstractDuring the last decade the X-ray observations ROSAT and ASCA have made it possible to distinguish between photospheric (thermal) and (nonthermal) magnetospheric radiation of single neutron stars. The next generation of X-ray satellites (Chandra, XMM and Astro-E) and the follow-up mission Constellation and XEUS- will allow spectroscopic and timing studies with much higher sensitivity and resolution. Primary future goals are to determine the chemical composition of neutron star photospheres and to measure the gravitational redshift of spectral features.

scholarly journals Merging of Iron Lines in Spectra of X-ray Burst Sources

1990 ◽  
Vol 115 ◽  
pp. 85-89
Author(s):  
J. Madej
Keyword(s):  
Neutron Star ◽  
Energy Range ◽  
Effective Temperature ◽  
Equivalent Width ◽  
Single Line ◽  
Spectral Features ◽  
X Ray ◽  
Synthetic Spectra

AbstractModel atmospheres and synthetic spectra of neutron star of the effective temperature 107 K are presented. All the iron spectral features in the energy range 6-10 keV (uncorrected for redshift) are washed out by instrumental or intrinsic broadening, which leaves only a single line of the equivalent width comparable with the observations.

scholarly journals Redshifted absorption lines from an isolated neutron star

2020 ◽  
Author(s):  
Sergio Campana
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Hydrogen Atmosphere ◽  
Oxygen Absorption ◽  
Spectral Features ◽  
Breeding Ground ◽  
X Ray ◽  
Cyclotron Absorption ◽  
Star Surface ◽  
Absorption Features

Abstract The solid crust constituting the outer layers of a hot neutron star is wrapped by an mm-to-cm thin atmosphere. Even if the atmosphere is so thin, it substantially affects the blackbody spectrum emitted by the surface, resulting in an overall hardening of the emitted spectrum. The composition of the atmosphere has so far remained elusive. Several narrow absorption features have been detected and interpreted as arising from proton (or electron) resonant cyclotron absorption in the neutron star magnetic field. Apart from these, for a Hydrogen atmosphere no spectral features are expected, whereas when it is polluted with metals, absorption features start appearing in soft X-ray spectra. Absorption edges and features have been possibly observed during thermonuclear explosions onto the neutron star surface. Isolated neutron stars represent a breeding ground where to look for absorption features, thanks to their simple X-ray spectra. Here we report on the detection of redshifted Nitrogen and Oxygen absorption features from the closest and brightest isolated neutron star. The lines are ~50 eV wide and their intensity is incompatible from originating in the interstellar path to the neutron star. Lines are redshifted by a common gravitational redshift of z_g=0.216±0.004.

scholarly journals Out of the Chorus Line: What Makes 1E 1207.4–5209 a Unique Object?

2004 ◽  
Vol 218 ◽  
pp. 273-276
Author(s):  
Andrea De Luca ◽  
Patrizia Caraveo ◽  
Sandro Mereghetti ◽  
Michele Moroni ◽  
Giovanni Bignami ◽  
...  
Keyword(s):  
Neutron Star ◽  
Spectral Features ◽  
X Ray ◽  
Spectral Behavior ◽  
Unique Object

The discovery of deep spectral features in the X-ray spectrum of 1E 1207.4–5209 has pushed this Isolated Neutron Star (INS) out of the chorus line, since no other INS has shown significant features in its X-ray continuum. On 2002 Aug, XMM-Newton devoted a two-orbit target-of-opportunity observation to this target, with the aim of better understanding the nature of such spectral features using much improved statistics. Indeed, the 260 ksec observation yielded 360 000 photons from 1E 1207.4–5209, allowing for a very sensitive study of the temporal and spectral behavior of this object.

scholarly journals Aperiodic Flux Variability in A 0535+262

1996 ◽  
Vol 165 ◽  
pp. 313-319
Author(s):  
Mark H. Finger ◽  
Robert B. Wilson ◽  
B. Alan Harmon ◽  
William S. Paciesas
Keyword(s):  
Neutron Star ◽  
Gamma Ray ◽  
Beat Frequency ◽  
Power Spectra ◽  
Center Frequency ◽  
X Ray ◽  
Binary Pulsar ◽  
Transient Source ◽  
Flux Variability ◽  
Burst And Transient Source

A “giant” outburst of A 0535+262, a transient X-ray binary pulsar, was observed in 1994 February and March with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory. During the outburst power spectra of the hard X-ray flux contained a QPO-like component with a FWHM of approximately 50% of its center frequency. Over the course of the outburst the center frequency rose smoothly from 35 mHz to 70 mHz and then fell to below 40 mHz. We compare this QPO frequency with the neutron star spin-up rate, and discuss the observed correlation in terms of the beat frequency and Keplerian frequency QPO models in conjunction with the Ghosh-Lamb accretion torque model.

scholarly journals A minimal timescale for the continuum in 4U 1608-52 and Aql X-1

2021 ◽  
Vol 502 (1) ◽  
pp. L72-L78
Author(s):  
K Mohamed ◽  
E Sonbas ◽  
K S Dhuga ◽  
E Göğüş ◽  
A Tuncer ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Spectra ◽  
Light Curves ◽  
State Transitions ◽  
Strong Positive Correlation ◽  
Present Evidence ◽  
X Ray ◽  
X Ray Binaries ◽  
The Continuum

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.

scholarly journals A NuSTAR confirmation of the 36 ks hard X-ray pulse-phase modulation in the magnetar 1E 1547.0 − 5408

2021 ◽  
Vol 502 (2) ◽  
pp. 2266-2284
Author(s):  
Kazuo Makishima ◽  
Teruaki Enoto ◽  
Hiroki Yoneda ◽  
Hirokazu Odaka
Keyword(s):  
Time Lapse ◽  
Phase Behaviour ◽  
Modulation Amplitude ◽  
Axial Deformation ◽  
Physical Processes ◽  
Arrival Times ◽  
Pulse Phase ◽  
Phase Variations ◽  
Complex Phenomena ◽  
Made In

ABSTRACT This paper describes an analysis of the NuSTAR data of the fastest-rotating magnetar 1E 1547 − 5408, acquired in 2016 April for a time lapse of 151 ks. The source was detected with a 1–60 keV flux of 1.7 × 10−11 erg s−1 cm−2, and its pulsation at a period of 2.086710(5) s. In 8–25 keV, the pulses were phase-modulated with a period of T = 36.0 ± 2.3 ks, and an amplitude of ∼0.2 s. This reconfirms the Suzaku discovery of the same effect at $T=36.0 ^{+4.5}_{-2.5}$ ks, made in the 2009 outburst. These results strengthen the view derived from the Suzaku data, that this magnetar performs free precession as a result of its axial deformation by ∼0.6 × 10−4, possibly caused by internal toroidal magneti fields (MFs) reaching ∼1016 G. Like in the Suzaku case, the modulation was not detected in energies below ∼8 keV. Above 10 keV, the pulse-phase behaviour, including the 36 ks modulation parameters, exhibited complex energy dependencies: at ∼22 keV, the modulation amplitude increased to ∼0.5 s, and the modulation phase changed by ∼65° over 10–27 keV, followed by a phase reversal. Although the pulse significance and pulsed fraction were originally very low in >10 keV, they both increased noticeably, when the arrival times of individual photons were corrected for these systematic pulse-phase variations. Possible origins of these complex phenomena are discussed, in terms of several physical processes that are specific to ultrastrong MFs.

scholarly journals The study of multipeaked type-I X-ray bursts in the neutron star low-mass X-ray binary 4U 1636 − 536 with RXTE

2020 ◽  
Vol 501 (1) ◽  
pp. 168-178
Author(s):  
Chen Li ◽  
Guobao Zhang ◽  
Mariano Méndez ◽  
Jiancheng Wang ◽  
Ming Lyu
Keyword(s):  
Neutron Star ◽  
Flux Ratio ◽  
Light Curves ◽  
Type I ◽  
X Ray ◽  
Soft State ◽  
Peak Flux ◽  
Low Mass ◽  
Two Peaks ◽  
Second Peak

ABSTRACT We have found and analysed 16 multipeaked type-I bursts from the neutron-star low-mass X-ray binary 4U 1636 − 53 with the Rossi X-ray Timing Explorer (RXTE). One of the bursts is a rare quadruple-peaked burst that was not previously reported. All 16 bursts show a multipeaked structure not only in the X-ray light curves but also in the bolometric light curves. Most of the multipeaked bursts appear in observations during the transition from the hard to the soft state in the colour–colour diagram. We find an anticorrelation between the second peak flux and the separation time between two peaks. We also find that in the double-peaked bursts the peak-flux ratio and the temperature of the thermal component in the pre-burst spectra are correlated. This indicates that the double-peaked structure in the light curve of the bursts may be affected by enhanced accretion rate in the disc, or increased temperature of the neutron star.

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