scholarly journals Probing X-ray emission in different modes of PSR J1023+0038 with a radio pulsar scenario

2019 ◽  
Vol 629 ◽  
pp. L8 ◽  
Author(s):  
S. Campana ◽  
A. Miraval Zanon ◽  
F. Coti Zelati ◽  
D. F. Torres ◽  
M. C. Baglio ◽  
...  
Keyword(s):  
Neutron Star ◽  
Spectral Properties ◽  
Source Parameters ◽  
High Mode ◽  
Radio Pulsar ◽  
Emission Model ◽  
Emission Mechanism ◽  
Pulsar Emission ◽  
X Ray ◽  
Pulsar Wind

Transitional pulsars provide us with a unique laboratory to study the physics of accretion onto a magnetic neutron star. PSR J1023+0038 (J1023) is the best studied of this class. We investigate the X-ray spectral properties of J1023 in the framework of a working radio pulsar during the active state. We modelled the X-ray spectra in three modes (low, high, and flare) as well as in quiescence, to constrain the emission mechanism and source parameters. The emission model, formed by an assumed pulsar emission (thermal and magnetospheric) plus a shock component, can account for the data only adding a hot dense absorber covering ∼30% of the emitting source in high mode. The covering fraction is similar in flaring mode, thus excluding total enshrouding, and decreases in the low mode despite large uncertainties. This provides support to the recently advanced idea of a mini-pulsar wind nebula (PWN), where X-ray and optical pulsations arise via synchrotron shock emission in a very close (∼100 km, comparable to a light cylinder), PWN-like region that is associated with this hot absorber. In low mode, this region may expand, pulsations become undetectable, and the covering fraction decreases.

scholarly journals X-ray study of high-and-low luminosity modes and peculiar low-soft-and-hard activity in the transitional pulsar XSS J12270−4859

2020 ◽  
Vol 635 ◽  
pp. A30 ◽  
Author(s):  
A. Miraval Zanon ◽  
S. Campana ◽  
A. Ridolfi ◽  
P. D’Avanzo ◽  
F. Ambrosino
Keyword(s):  
Spectral Analysis ◽  
Neutron Star ◽  
High Mode ◽  
Radio Pulsar ◽  
X Ray ◽  
Low Mass ◽  
Pulsar Wind ◽  
Mode Transitions ◽  
Star Surface ◽  
Mode A

XSS J12270−4859 (henceforth J12270) is the first low-mass X-ray binary to exhibit a transition, taking place at the end of 2012, from an X-ray active state to a radio pulsar state. The X-ray emission based on archival XMM-Newton observations is highly variable, showing rapid variations (∼10 s) from a high X-ray luminosity mode to a low mode and back. A flaring mode has also been observed. X-ray pulsations have been detected during the high mode only. In this work we present two possible interpretations for the rapid swings between the high and low modes. In the first scenario, this phenomenon can be explained by a rapid oscillation between a propeller state and a radio-ejection pulsar state, during which the pulsar wind prevents matter from falling onto the neutron star surface. In the second scenario, a radio pulsar is always active, the intra-binary shock is located just outside the light cylinder in the high mode, while it expands during the low mode. At variance with other transitional pulsars, J12270 shows two instances of the low mode: a low-soft and low-hard mode. Performing an X-ray spectral analysis, we show that the harder component, present in the low-hard spectra, is probably related to the tail of the flare emission. This supports the understanding that the flare mechanism is independent of the high-to-low mode transitions.

scholarly journals Correlation between the X-ray Spectra of Young Pulsars and their Wind Nebulae

2003 ◽  
Vol 214 ◽  
pp. 163-166
Author(s):  
E. V. Gotthelf
Keyword(s):  
Linear Relationship ◽  
Current Theory ◽  
Shock Acceleration ◽  
Observational Constraints ◽  
Emission Mechanism ◽  
Pulsar Emission ◽  
X Ray ◽  
Pulsar Wind

A significant correlation is discovered between the X-ray spectra of young pulsars (PSRs) and that of their associated wind nebulae (PWNe). For a sample of nine bright Crab-like pulsar systems observed with the Chandra X-ray observatory, we report a linear relationship between the photon indices for the PWNe and those of the phase-averaged pulsar emission, where ΓPWN = 0.72 ± 0.13 × ΓPSR + 0.86 ± 0.20. Furthermore, we find that the spectral slopes of younger, more energetic, pulsars tend to be steeper. These results confirm a consistent pulsar emission mechanism and provide important new observational constraints on the current theory of shock acceleration models for pulsar wind emission.

scholarly journals Swift/XRT, Chandra, and XMM–Newton observations of IGR J17091–3624 as it returns into quiescence

2020 ◽  
Vol 497 (1) ◽  
pp. 1115-1126
Author(s):  
M Pereyra ◽  
D Altamirano ◽  
J M C Court ◽  
N Degenaar ◽  
R Wijnands ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Time Scales ◽  
Strong Evidence ◽  
Spectral Properties ◽  
X Ray ◽  
Term Evolution ◽  
Wide Range ◽  
Low Mass

ABSTRACT IGR J17091–3624 is a low-mass X-ray binary (LMXB), which received wide attention from the community thanks to its similarities with the bright black hole system GRS 1915+105. Both systems exhibit a wide range of highly structured X-ray variability during outburst, with time-scales from few seconds to tens of minutes, which make them unique in the study of mass accretion in LMXBs. In this work, we present a general overview into the long-term evolution of IGR J17091–3624, using Swift/XRT observations from the onset of the 2011–2013 outburst in 2011 February till the end of the last bright outburst in 2016 November. We found four re-flares during the decay of the 2011 outburst, but no similar re-flares appear to be present in the latter one. We studied, in detail, the period with the lowest flux observed in the last 10 yr, just at the tail end of the 2011–2013 outburst, using Chandra and XMM-Newton observations. We observed changes in flux as high as a factor of 10 during this period of relative quiescence, without strong evidence of softening in the spectra. This result suggests that the source has not been observed at its true quiescence so far. By comparing the spectral properties at low luminosities of IGR J17091–3624 and those observed for a well-studied population of LMXBs, we concluded that IGR J17091–3624 is most likely to host a black hole as a compact companion rather than a neutron star.

scholarly journals EARLY PHASES OF DIFFERENT TYPES OF ISOLATED NEUTRON STAR

2005 ◽  
Vol 14 (06) ◽  
pp. 1075-1082 ◽  
Author(s):  
AŞKIN ANKAY ◽  
SERKAN ŞAHIN ◽  
GÖKÇE KARANFIL ◽  
EFE YAZGAN
Keyword(s):  
Neutron Star ◽  
Thermal Neutron ◽  
Early Phase ◽  
Radio Pulsar ◽  
Radio Pulsars ◽  
X Ray ◽  
Soft Gamma Repeaters ◽  
Different Types ◽  
Early Phases

Two Galactic isolated strong X-ray pulsars seem to be in the densest environments compared to other types of Galactic pulsar. X-ray pulsar J1846-0258 can be in an early phase of anomalous X-ray pulsars and soft gamma repeaters if its average braking index is ~1.8–2.0. X-ray pulsar J1811-1925 must have a very large average braking index (~11) if this pulsar was formed by SN 386AD. This X-ray pulsar can be in an early phase of the evolution of the radio pulsars located in the region P ~ 50–150 ms and Ṗ ~ 10-14–10-16 ss -1 of the P–Ṗ diagram. X-ray/radio pulsar J0540-69 seems to be evolving in the direction to the dim isolated thermal neutron star region on the P–Ṗ diagram. Possible progenitors of different types of neutron star are also discussed.

scholarly journals Revealing the Physical Changes Taking Place in Z-Track Motion in Low Mass X-Ray Binaries

2004 ◽  
Vol 194 ◽  
pp. 206-206
Author(s):  
M. Bałucińska-Church ◽  
M. J. Church ◽  
G. Halai ◽  
A. Szostek
Keyword(s):  
Neutron Star ◽  
Emission Model ◽  
Spectral Evolution ◽  
X Ray ◽  
Astrophysical Problem ◽  
Low Mass ◽  
Physical Changes ◽  
First Time ◽  
X Ray Binaries

The explanation of the strong physical changes clearly taking place in the Z-track class of Low Mass X-ray Binaries has so far not been obtained, and this remains a significant astrophysical problem, without which we cannot claim to understand accretion in LMXB. We have for the first time applied the Birmingham emission model (2,3) to this problem to attempt to obtain a solution from the spectral evolution along the Z-track in the source GX 340+0 observed with Rossi- ХTE. In this model, X-ray emission consists of blackbody from the neutron star, plus Comptonized emission from an extended ADC.

scholarly journals Intensive X-ray Monitoring of the 16ms Crab-like Pulsar PSR J0537 – 6910

2000 ◽  
Vol 177 ◽  
pp. 335-340
Author(s):  
F. E. Marshall ◽  
E. V. Gotthelf ◽  
J. Middleditch ◽  
Q. D. Wang ◽  
W. Zhang
Keyword(s):  
Neutron Star ◽  
Maximum Rate ◽  
Supernova Remnant ◽  
Large Magellanic Cloud ◽  
Crab Pulsar ◽  
Pulsar Emission ◽  
X Ray ◽  
Intensive Monitoring ◽  
Unique Probe ◽  
Pulse Timing

AbstractThe recently discovered pulsar PSR J0537-6910 is the most rapidly rotating young pulsar known. This latest example of a Crab-like pulsar, located in the supernova remnant N157B in the Large Magellanic Cloud, is rotating twice as fast as the Crab pulsar. With a characteristic age of 5000 years, it is also the oldest known example of a Crab-like pulsar and was likely rotating close to the maximum rate for a neutron star when it was born. Here we report preliminary results from an intensive monitoring campaign of X-ray observations acquired with the Rossi X-ray Timing Explorer that began in January 1999. These observation have revealed a large glitch event in the pulse timing during the first six month of our campaign, consistent with those suggested by sparse observations dating back to 1993. The current evolution of the rotation rate of PSR J0537-6910 provides a unique probe of the internal structure of neutron stars and constraints on possible pulsar emission mechanisms.

scholarly journals Chandra Observations of the Guitar Nebula

2003 ◽  
Vol 214 ◽  
pp. 135-136 ◽  
Author(s):  
Diane S. Wong ◽  
James M. Cordes ◽  
Shami Chatterjee ◽  
Ellen G. Zweibel ◽  
John P. Finley ◽  
...  
Keyword(s):  
Proper Motion ◽  
Hot Spot ◽  
Optical Emission ◽  
Position Angle ◽  
Bow Shock ◽  
Radio Pulsar ◽  
X Ray ◽  
Multi Wavelength ◽  
Pulsar Wind

As part of a multi-wavelength study, we report on a 50 ks Chandra/ACIS observation of the Guitar Nebula, a bow shock nebula associated with the radio pulsar B2224+65. We see a “hot spot” at the tip of the bow shock. We also notice a “jet” of X-ray emission at position angle (PA) −69°. However, the proper motion of the pulsar and the axis of optical emission is at PA 52°.1. We discuss the resulting interpretations of the relativistic pulsar wind and the surrounding ISM.

scholarly journals Enhanced x-ray emission coinciding with giant radio pulses from the Crab Pulsar

Science ◽  
2021 ◽  
Vol 372 (6538) ◽  
pp. 187-190
Author(s):  
Teruaki Enoto ◽  
Toshio Terasawa ◽  
Shota Kisaka ◽  
Chin-Ping Hu ◽  
Sebastien Guillot ◽  
...  
Keyword(s):  
Optical Emission ◽  
Crab Pulsar ◽  
Radio Bursts ◽  
Emission Mechanism ◽  
Pulsar Emission ◽  
X Ray ◽  
Percentage Points

Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars that last a few microseconds and are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside of radio wavelengths is from the Crab Pulsar, where optical emission is enhanced by a few percentage points during GRPs. We observed the Crab Pulsar simultaneously at x-ray and radio wavelengths, finding enhancement of the x-ray emission by 3.8 ± 0.7% (a 5.4σ detection) coinciding with GRPs. This implies that the total emitted energy from GRPs is tens to hundreds of times higher than previously known. We discuss the implications for the pulsar emission mechanism and extragalactic fast radio bursts.

scholarly journals Radius-to-Frequency Mapping in the Radio Pulsar Emission Mechanism

1992 ◽  
Vol 128 ◽  
pp. 143-146
Author(s):  
S. E. Thorsett
Keyword(s):  
General Feature ◽  
Low Frequency ◽  
Radio Pulsar ◽  
Emission Mechanism ◽  
Polar Cap ◽  
Pulsar Emission ◽  
Pulsar Timing ◽  
Average Profile ◽  
Different Altitudes

AbstractA general feature of many models of the pulsar emission mechanism is that radiation of different frequencies is produced at different altitudes above the polar cap. The broadening of pulse components and increasing separation between components at low frequency is in general agreement with these theories. We review the available average profile and pulsar timing observations and discuss the implications for theories of radius-to-frequency mapping.

scholarly journals Recycling in progress: RXTE discovery of the first accretion-powered millisecond pulsar

2000 ◽  
Vol 177 ◽  
pp. 643-648
Author(s):  
M. van der Klis
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Binary System ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Radio Pulsar ◽  
Millisecond Pulsar ◽  
X Ray ◽  
Millisecond Radio

AbstractThe discovery is reported of the first accretion-powered millisecond pulsar, SAX J 1808.4–3658. This 2.5 millisecond pulsar has a magnetic field strength of 1–10108Gauss and has all the characteristics of the long-predicted millisecond radio pulsar progenitor, a neutron star in an X-ray binary system where the process of recycling is taking place at this time.

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