scholarly journals Chandra observations of black widow pulsars

2012 ◽  
Vol 8 (S291) ◽  
pp. 389-391 ◽  
Author(s):  
P. Gentile ◽  
M. McLaughlin ◽  
M. Roberts ◽  
F. Camilo ◽  
J. Hessels ◽  
...  
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
The Other ◽  
Emission Characteristic ◽  
Black Widow ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Significant Variability ◽  
Binary Orbit

AbstractWe describe the first X-ray observations of binary millisecond pulsars PSR J0023+0923, J1810+1744, J2215+5135, and J2256−1024. All are Fermi gamma-ray sources and three are ‘black-widow’ pulsars, with companions of mass < 0.1 M⊙. Data were taken using the Chandra X-Ray Observatory and covered a full binary orbit for each pulsar. PSRs J2215+5135 and J2256−1024, show significant orbital variability and X-ray flux minima coinciding with eclipses seen at radio wavelengths. This is consistent with intrabinary shock emission characteristic of black-widow pulsars. The other two pulsars, PSRs J0023+0923 and J1810+1744, do not demonstrate significant variability, but are fainter than the other two sources. Spectral fits yield power-law indices that range from 1.4 to 2.3 and blackbody temperatures in the hundreds of eV. The spectrum for PSR J2215+5135 shows a significant hard X-ray component (41% of counts are above 2 keV), which is additional evidence for the presence of intrabinary shock emission.

Sigma upper limits to the hard X-ray/soft gamma-ray emission from the millisecond pulsars of the nearby globular cluster 47 Tucunae

1993 ◽  
Vol 405 ◽  
pp. L59 ◽  
Author(s):  
D. Barret ◽  
P. Mandrou ◽  
M. Denis ◽  
J. F. Olive ◽  
P. Laurent ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Gamma Ray ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Upper Limits ◽  
Gamma Ray Emission

scholarly journals X-ray and gamma-ray emission from millisecond pulsars

2003 ◽  
Vol 398 (2) ◽  
pp. 639-646 ◽  
Author(s):  
L. Zhang ◽  
K. S. Cheng
Keyword(s):  
Gamma Ray ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Gamma Ray Emission

scholarly journals On the Relation Between GRB Classes and X-ray Flashes

10.14311/1496 ◽  
2012 ◽  
Vol 52 (1) ◽  
Author(s):  
Z. Bagoly ◽  
P. Veres ◽  
I. Horváth ◽  
A. Mészáros ◽  
L. G. Balázs
Keyword(s):  
Physical Properties ◽  
Short Duration ◽  
Classification Scheme ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
The Other ◽  
X Ray ◽  
Intermediate Group ◽  
Long Duration

Gamma-ray bursts are usually classified into either short-duration or long-duration bursts. Going beyond the short-long classification scheme, it has been shown on statistical grounds that a third, intermediate population is needed in this classification scheme. We are looking for physical properties which discriminate the intermediate duration bursts from the other two classes. As the intermediate group is the softest, we argue that we have related them with X-ray flashes among the GRBs. We give a new, probabilistic definition for this class of events.

scholarly journals Less noticeable shallow decay phase in early X-ray afterglows of GeV/TeV-detected gamma-ray bursts

2020 ◽  
Vol 494 (4) ◽  
pp. 5259-5269 ◽  
Author(s):  
Ryo Yamazaki ◽  
Yuri Sato ◽  
Takanori Sakamoto ◽  
Motoko Serino
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
High Energy ◽  
Decay Phase ◽  
Power Law Model ◽  
X Ray ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

ABSTRACT The nature of the shallow decay phase in the X-ray afterglow of the gamma-ray burst (GRB) is not yet clarified. We analyse the data of early X-ray afterglows of 26 GRBs triggered by Burst Alert Telescope onboard Neil Gehrels Swift Observatory and subsequently detected by Fermi Large Area Telescope (LAT) and/or Imaging Atmospheric Cherenkov Telescopes. It is found that nine events (including two out of three very-high-energy gamma-ray events) have no shallow decay phase and that their X-ray afterglow light curves are well described by single power-law model except for the jet break at later epoch. The rest are fitted by double power-law model and have a break in the early epoch (around ks), however, eight events (including a very-high-energy gamma-ray event) have the pre-break decay index larger than 0.7. We also analyse the data of well-sampled X-ray afterglows of GRBs without LAT detection and compare their decay properties with those of high-energy and very-high-energy gamma-ray events. It is found that for the GeV/TeV bursts, the fraction of events whose X-ray afterglows are described by single power law is significantly larger than those for non-GeV/TeV GRBs. Even if the GeV/TeV GRBs have shallow decay phase, their decay slope tends to be steeper than non-GeV/TeV bursts, that is, they have less noticeable shallow decay phase in the early X-ray afterglow. A possible interpretation along with the energy injection model is briefly discussed.

scholarly journals Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Hiromasa Suzuki ◽  
Aya Bamba ◽  
Ryo Yamazaki ◽  
Yutaka Ohira
Keyword(s):  
Power Law ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Spectral Shape ◽  
X Ray ◽  
Galactic Cosmic Ray ◽  
High Energy Particles ◽  
Accelerated Particles

Abstract In the current decade, GeV/TeV gamma-ray observations of several supernova remnants (SNRs) have implied that accelerated particles are escaping from their acceleration sites. However, when and how they escape from the SNR vicinities are yet to be understood. Recent studies have suggested that the particle escape might develop with thermal plasma ages of the SNRs. We present a systematic study on the time evolution of particle escape using thermal X-ray properties and gamma-ray spectra using 38 SNRs associated with GeV/TeV gamma-ray emissions. We conducted spectral fittings on the gamma-ray spectra using exponential cutoff power-law and broken power-law models to estimate the exponential cutoff or the break energies, both of which are indicators of particle escape. Plots of the gamma-ray cutoff/break energies over the plasma ages show similar tendencies to those predicted by analytical/numerical calculations of particle escape under conditions in which a shock is interacting with thin interstellar medium or clouds. The particle escape timescale is estimated as ∼100 kyr from the decreasing trends of the total energy of the confined protons with the plasma age. The large dispersions of the cutoff/break energies in the data may suggest an intrinsic variety of particle escape environments. This might be the cause of the complicated Galactic cosmic ray spectral shape measured on Earth.

scholarly journals Characterization of gamma-ray burst prompt emission spectra down to soft X-rays

2018 ◽  
Vol 616 ◽  
pp. A138 ◽  
Author(s):  
G. Oganesyan ◽  
L. Nava ◽  
G. Ghirlanda ◽  
A. Celotti
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
Emission Spectra ◽  
X Rays ◽  
Mean Values ◽  
X Ray ◽  
Peak Energy ◽  
Low Energies ◽  
Prompt Emission

Detection of prompt emission by Swift-XRT provides a unique tool to study how the prompt spectrum of gamma-ray bursts (GRBs) extends down to the soft X-ray band. This energy band is particularly important for prompt emission studies, since it is towards low energies that the observed spectral shape is in disagreement with the synchrotron predictions. Unfortunately, the number of cases where XRT started observing the GRB location during the prompt phase is very limited. In this work, we collect a sample of 34 GRBs and perform joint XRT+BAT spectral analysis of prompt radiation, extending a previous study focused on the 14 brightest cases. Fermi-GBM observations are included in the analysis when available (11 cases), allowing the characterization of prompt spectra from soft X-rays to MeV energies. In 62% of the spectra, the XRT data reveal a hardening of the spectrum, well described by introducing an additional, low-energy power-law segment (with index α1) into the empirical fitting function. The break energy below which the spectrum hardens has values between 3 keV and 22 keV. A second power-law (α2) describes the spectrum between the break energy and the peak energy. The mean values of the photon indices are 〈α1〉 = −0.51 (σ = 0.24) and 〈α2〉 = −1.56 (σ = 0.26). These are consistent, within one σ, with the synchrotron values in fast cooling regime. As a test, if we exclude XRT data from the fits we find typical results: the spectrum below the peak energy is described by a power law with 〈α〉 = −1.15. This shows the relevance of soft X-ray data in revealing prompt emission spectra consistent with synchrotron spectra. Finally, we do not find any correlation between the presence of the X-ray break energy and the flux, fluence, or duration of the prompt emission.

scholarly journals The GBT 350-MHz Drift Scan Pulsar Survey – III. Detection of a magnetic field in the eclipsing material of PSR J2256–1024

2020 ◽  
Vol 495 (3) ◽  
pp. 3052-3064
Author(s):  
Kathryn Crowter ◽  
Ingrid H Stairs ◽  
Christie A McPhee ◽  
Anne M Archibald ◽  
Jason Boyles ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Zero Magnetic Field ◽  
Line Of Sight ◽  
Black Widow ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Potential Source ◽  
Rotation Measure ◽  
Drift Scan ◽  
Polarization Profiles

ABSTRACT We present the first measurement of a non-zero magnetic field in the eclipsing material of a black widow pulsar. Black widows are millisecond pulsars which are ablating their companions; therefore they are often proposed as one potential source of isolated millisecond pulsars. PSR J2256–1024 is an eclipsing black widow discovered at radio wavelengths and later also observed in the X-ray and gamma parts of the spectrum. Here we present the radio timing solution for PSR J2256–1024; polarization profiles at 350, 820, and 1500 MHz; and an investigation of changes in the polarization profile due to eclipsing material in the system. In the latter we find evidence of Faraday rotation in the linear polarization shortly after eclipse, measuring a rotation measure of 0.44(6) rad m−2 and a corresponding line-of-sight magnetic field of ∼1.11(16) mG.

scholarly journals Using Swift observations of prompt and afterglow emission to classify GRBs

2007 ◽  
Vol 365 (1854) ◽  
pp. 1179-1188 ◽  
Author(s):  
Paul T O'Brien ◽  
Richard Willingale
Keyword(s):  
Light Curve ◽  
Power Law ◽  
Gamma Ray ◽  
Good Description ◽  
X Ray ◽  
Temporal Properties ◽  
Power Law Decay ◽  
Decay Index ◽  
Prompt Emission ◽  
Burst Alert Telescope

We present an analysis of early Burst Alert Telescope and X-ray Telescope data for 107 gamma-ray bursts (GRBs) observed by the Swift satellite. We use these data to examine the behaviour of the X-ray light curve and propose a classification scheme for GRBs based on this behaviour. As found for previous smaller samples, the earliest X-ray light curve can be well described by an exponential, which relaxes into a power-law, often with flares superimposed. The later emission is well fit using a similar functional form and we find that these two functions provide a good description of the entire X-ray light curve. For the prompt emission, the transition time between the exponential and the power-law gives a well-defined time-scale, T p , for the burst duration. We use T p , the spectral index of the prompt emission, β p , and the prompt power-law decay index, α p , to define four classes of burst: short, slow, fast and soft. Bursts with slowly declining emission have spectral and temporal properties similar to the short bursts despite having longer durations. Some of these GRBs may therefore arise from similar progenitors including several types of binary system. Short bursts tend to decline more gradually than longer duration bursts and hence emit a significant fraction of their total energy at times greater than T p . This may be due to differences in the environment or the progenitor for long, fast bursts.

Energy spectrum of diffuse primary X rays up to 180 keV

1968 ◽  
Vol 46 (10) ◽  
pp. S461-S465 ◽  
Author(s):  
J. A. M. Bleeker ◽  
J. J. Burger ◽  
A. J. M. Deerenberg ◽  
A. Scheepmaker ◽  
B. N. Swanenburg ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Power Law ◽  
Plastic Scintillator ◽  
Geomagnetic Latitude ◽  
Cosmic Ray ◽  
Rotating Disk ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Good Agreement

Two balloon flights with identical X-ray detectors were carried out in the summer of 1966, one from De Bilt, the Netherlands (geomagnetic latitude 53 °N), and the other from Taiyomura, Japan (geomagnetic latitude 25 °N). The detector consists of a NaI(Tl) crystal, 12.5 mm thick and 50 mm in diameter, surrounded by an effective collimator-shield and a plastic scintillator guard counter. The rotating disk incorporated enables the separation of "forward" X rays from the cosmic-ray-induced background. The results of the flights are in very good agreement with each other. In view of the rather large difference in geomagnetic latitude in these two flights, this agreement supports the celestial origin of the primary X rays observed. The energy spectrum between 20 and 180 keV can be expressed by a power law:[Formula: see text]

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