scholarly journals CONSTRAINING THE PULSAR POWER IN GAMMA-RAY BINARIES THROUGH THERMAL X-RAY EMISSION

2012 ◽  
Vol 08 ◽  
pp. 132-137
Author(s):  
VÍCTOR ZABALZA ◽  
VALENTÍ BOSCH-RAMON ◽  
JOSEP MARIA PAREDES
Keyword(s):  
Stellar Wind ◽  
Binary Systems ◽  
Massive Star ◽  
Gamma Ray ◽  
Thermal Emission ◽  
Mass Loss Rate ◽  
X Rays ◽  
Orbital Inclination ◽  
X Ray ◽  
Pulsar Wind

Gamma-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds collide producing non-thermal emission, most likely from the shocked pulsar wind. Thermal X-rays are expected from the shocked stellar wind, with a spectrum akin to the one observed in massive star binaries. The goal of this work is, through the study of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, constrain the pulsar spin-down luminosity and the stellar wind properties. A semi-analytic model is developed to compute the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries. The model results are compared with XMM-Newton observations of LS 5039, a candidate pulsar gamma-ray binary with a strong stellar wind. Exploring the range of possible values for the stellar mass-loss rate and orbital inclination, we obtain an upper limit on the pulsar spin-down luminosity of 6 × 1036 erg s-1. We conclude that, to explain the non-thermal luminosity of LS 5039 in the pulsar wind scenario, a non-thermal to spin-down luminosity ratio very close to unity may be required.

scholarly journals High Resolution X-ray Observations of 3C 58

2004 ◽  
Vol 218 ◽  
pp. 185-188
Author(s):  
Patrick Slane
Keyword(s):  
High Resolution ◽  
Massive Star ◽  
Thermal Emission ◽  
Rotation Axis ◽  
Crab Nebula ◽  
X Ray ◽  
The Galaxy ◽  
Pulsar Wind ◽  
Star Surface ◽  
The Crab Nebula

As the presumed remnant of SN 1181, 3C 58 houses one of the youngest known neutron stars in the Galaxy. The properties of this young pulsar and its associated pulsar wind nebula (PWN) differ considerably from those of the Crab Nebula, and may well offer a more typical example of the endpoint of massive star collapse. High resolution X-ray studies reveal structures in the inner nebula that may be associated with the pulsar wind termination shock, a jet that may be aligned with the rotation axis, and other regions of enhanced emission. Spectral variations in the PWN are consistent with the expected evolution of the postshock flow, and complex loops of emission are seen in the nebula interior. Limits on the neutron star surface temperature fall below standard cooling models, indicating that some more rapid neutrino cooling process is required. The outer regions of 3C 58 show thermal emission with enhanced levels of neon, indicative of shocked ejecta bounding the PWN.

scholarly journals Gamma-ray-emitting narrow-line Seyfert 1 galaxies: the Swift view

2020 ◽  
Vol 496 (2) ◽  
pp. 2213-2229 ◽  
Author(s):  
F D’Ammando
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
Optical Emission ◽  
X Rays ◽  
Narrow Line ◽  
X Ray ◽  
Relativistic Jet ◽  
Photon Index ◽  
Γ Ray ◽  
Lower Variability

ABSTRACT We report the analysis of all Swift observations available up to 2019 April of γ-ray-emitting narrow-line Seyfert 1 galaxies (NLSy1). The distribution of X-ray luminosities (and fluxes) indicates that the jet radiation significantly contributes to their X-ray emission, with Doppler boosting making values higher than other radio-loud NLSy1. The 0.3–10 keV photon indices are on average harder with respect to radio-quiet and radio-loud NLSy1, confirming a dominant jet contribution in X-rays. However, the lower variability amplitude with respect to blazars and the softening of the spectrum in some periods suggests that also the corona radiation contributes to the X-ray emission. In optical and ultraviolet (UV) significant flux changes have been observed on daily, weekly, and monthly time-scale, providing a clear indication of the significant contribution of the jet radiation in this part of spectrum. A strong correlation between X-ray, UV, and optical emission and simultaneous flux variations have been observed in 1H 0323+342, SBS 0846+513, PMN J0948+0022 as expected in case the jet radiation is the dominant mechanism. Correlated multiband variability favours the jet-dominated scenario also in FBQS J1644+2619 and PKS 2004−447. The summed X-ray Telescope spectra of 1H 0323+342, SBS 0846+513, PMN J0948+0022, and FBQS J1644+2619 are well fitted by a broken power law with a break around 2 keV. The spectrum above 2 keV is dominated by the non-thermal emission from a beamed relativistic jet, as suggested by the hard photon index. A Seyfert-like feature like the soft X-ray excess has been observed below 2 keV, making these γ-ray-emitting NLSy1 different from typical blazars.

Mass Loss and Stellar Wind in Massive X-Ray Binaries

1980 ◽  
Vol 5 ◽  
pp. 541-547
Author(s):  
H. F. Henrichs
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Binary Systems ◽  
Massive Stars ◽  
Compact Star ◽  
X Rays ◽  
Early Type ◽  
X Ray ◽  
X Ray Binaries ◽  
Loss Rates

A number of massive stars of early type is found in X-ray binary systems. The catalog of Bradt et al. (1979) contains 21 sources optically identified with massive stars ranging in spectral type from 06 to B5 out of which 13 are (nearly) unevolved stars and 8 are supergiants. Single stars of this type generally show moderate to strong stellar winds. The X-rays in these binaries originate from accretion onto a compact companion (we restrict the discussion to this type of X-rays).We consider the compact star as a probe traveling through the stellar wind. This probe enables us to derive useful information about the mass outflow of massive stars.After presenting the basic data we derive an upper limit to mass loss rates of unevolved early type stars by studying X-ray pulsars. Next we consider theoretical predictions concerning the influence of X-rays on the stellar wind and compare these with the observations. Finally, using new data from IUE, we draw some conclusions about mass loss rates and velocity laws as derived from X-ray binaries.

scholarly journals Searching for X-ray counterparts of Fermi Gamma-ray pulsars in Suzaku observations

2011 ◽  
Vol 7 (S279) ◽  
pp. 317-318 ◽  
Author(s):  
Yu Aoki ◽  
Takahiro Enomoto ◽  
Yoichi Yatsu ◽  
Nobuyuki Kawai ◽  
Takeshi Nakamori ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
Flux Ratio ◽  
Radio Pulsars ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Absorbed Power ◽  
Pulsar Wind ◽  
Error Circle

AbstractWe report the Suzaku follow-up observations of the Gamma-ray pulsars, 1FGL J0614,13328, J1044.55737, J1741.82101, and J1813.31246, which were discovered by the Fermi Gamma-ray observatory. Analysing Suzaku/XIS data, we detected X-ray counterparts of these pulsars in the Fermi error circle and interpreted their spectra with absorbed power-law functions. These results indicate that the origin of these X-ray sources is non-thermal emission from the pulsars or from Pulsar Wind Nebulae (PWNe) surrounding them. Moreover we found that J1741.82101 exhibits a peculiar profile: spin-down luminosity vs flux ratio between X- and gamma-rays is unusually large compared to usual radio pulsars.

scholarly journals X-ray diagnostics of massive star winds

2016 ◽  
Vol 12 (S329) ◽  
pp. 151-155
Author(s):  
L. M. Oskinova ◽  
R. Ignace ◽  
D. P. Huenemoerder
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Massive Star ◽  
Massive Stars ◽  
Stellar Winds ◽  
X Rays ◽  
Early Type ◽  
Stellar Rotation ◽  
X Ray ◽  
Early Type Stars

AbstractObservations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

scholarly journals Modelling multiwavelength emissions from PSR B1259–63/LS 2883: Effects of the stellar disc on shock radiations

2019 ◽  
Vol 627 ◽  
pp. A87 ◽  
Author(s):  
A. M. Chen ◽  
J. Takata ◽  
S. X. Yi ◽  
Y. W. Yu ◽  
K. S. Cheng
Keyword(s):  
Magnetic Field ◽  
Gamma Ray ◽  
Thermal Emission ◽  
Orbital Plane ◽  
Light Curves ◽  
Double Peak ◽  
Stellar Disc ◽  
X Ray ◽  
Pulsar Wind ◽  
Star Binary

PSR B1259–63/LS 2883 is an elliptical pulsar/Be star binary that emits broadband emissions from radio to TeV γ-rays. The massive star possesses an equatorial disc that is inclined with the orbital plane of the pulsar. Non-thermal emission from the system is believed to be produced by pulsar wind shock and double-peak profiles in the X-ray, and TeV γ-ray light curves are related to the phases of the pulsar passing through the disc region of the star. In this paper, we investigate the interactions between the pulsar wind and stellar outflows, especially with the presence of the disc, and present a multiwavelength modelling of the emission from this system. We show that the double-peak profiles of X-ray and TeV γ-ray light curves are caused by the enhancements of the magnetic field and soft photons at the shock during the disc passages. As the pulsar is passing through the equatorial disc, the additional pressure of the disc pushes the shock surface closer to the pulsar, which causes the enhancement of magnetic field in the shock, and thus increases the synchrotron luminosity. The TeV γ-rays due to the inverse-Compton (IC) scattering of shocked electrons with seed photons from the star are expected to peak around periastron, which is inconsistent with observations. However, the shock heating of the stellar disc could provide additional seed photons for IC scattering during the disc passages, and thus produces the double-peak profiles as observed in the TeV γ-ray light curve. Our model can possibly be examined and applied to other similar gamma-ray binaries, such as PSR J2032+4127/MT91 213, HESS J0632+057, and LS I+61°303.

scholarly journals Stellar winds in high-mass X-ray binaries

1995 ◽  
Vol 163 ◽  
pp. 271-279
Author(s):  
Lex Kaper
Keyword(s):  
Stellar Wind ◽  
Large Scale ◽  
Binary Systems ◽  
Compact Object ◽  
High Mass ◽  
X Rays ◽  
Ionization Zone ◽  
X Ray ◽  
Massive Binary Systems ◽  
X Ray Binaries

High-mass X-ray binaries (HMXBs) represent an important stage in the evolution of massive binary systems. The compact object (in most cases an X-ray pulsar) not only provides information on the orbital and stellar parameters, but also probes the stellar wind of the massive companion, an OB supergiant or Be star. The X-ray luminosity directly depends on the density and the velocity of the wind at the orbit of the X-ray source. Important constraints on the stellar-wind structure can be set by studying the orbital modulation of UV P-Cygni profiles. In this paper different aspects of the interactive wind-accretion process are highlighted, such as the highly variable X-ray luminosity, the influence of the X-rays on the radiative acceleration of the wind inside the ionization zone, and the large-scale structures that trail the X-ray source in its orbit.

scholarly journals Wind inhibition by X-ray irradiation in HMXBs: the influence of clumping and the final X-ray luminosity

2018 ◽  
Vol 620 ◽  
pp. A150 ◽  
Author(s):  
J. Krtička ◽  
J. Kubát ◽  
I. Krtičková
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Terminal Velocity ◽  
High Mass ◽  
Small Scale ◽  
X Rays ◽  
X Ray ◽  
X Ray Binaries

Context. In wind-powered X-ray binaries, the radiatively driven stellar wind from the primary may be inhibited by the X-ray irradiation. This creates the feedback that limits the X-ray luminosity of the compact secondary. Wind inhibition might be weakened by the effect of small-scale wind inhomogeneities (clumping) possibly affecting the limiting X-ray luminosity. Aims. We study the influence of X-ray irradiation on the stellar wind for different radial distributions of clumping. Methods. We calculate hot star wind models with external irradiation and clumping using our global wind code. The models are calculated for different parameters of the binary. We determine the parameters for which the X-ray wind ionization is so strong that it leads to a decrease of the radiative force. This causes a decrease of the wind velocity and even of the mass-loss rate in the case of extreme X-ray irradiation. Results. Clumping weakens the effect of X-ray irradiation because it favours recombination and leads to an increase of the wind mass-loss rate. The best match between the models and observed properties of high-mass X-ray binaries (HMXBs) is derived with radially variable clumping. We describe the influence of X-ray irradiation on the terminal velocity and on the mass-loss rate in a parametric way. The X-ray luminosities predicted within the Bondi-Hoyle-Lyttleton theory agree nicely with observations when accounting for X-ray irradiation. Conclusions. The ionizing feedback regulates the accretion onto the compact companion resulting in a relatively stable X-ray source. The wind-powered accretion model can account for large luminosities in HMXBs only when introducing the ionizing feedback. There are two possible states following from the dependence of X-ray luminosity on the wind terminal velocity and mass-loss rate. One state has low X-ray luminosity and a nearly undisturbed wind, and the second state has high X-ray luminosity and exhibits a strong influence of X-rays on the flow.

scholarly journals Coma Cluster: CR Acceleration and Gamma-Ray Production

1996 ◽  
Vol 175 ◽  
pp. 341-342
Author(s):  
A.V. Dogiel
Keyword(s):  
Gamma Ray ◽  
Thermal Emission ◽  
North Pole ◽  
X Rays ◽  
Coma Cluster ◽  
X Ray ◽  
The North ◽  
Intracluster Gas

The Coma cluster is situated near to the North Pole and its galactic coordinates are: l≃ 50° and b≃87°. The distance to the cluster is about 138 Mpc. Observations in soft X-rays (see e.g. Briel, 1992) discovered there the thermal emission from the diffuse hot intracluster gas whose density and temperature are: n≃ 3 · 10–3 cm–3 and T≃ 108K. Measurements of hard X-ray flux from Coma showed controversial detection in different experiments (see Bazzano et al. 1990 and Rephaeli et al. 1994).

scholarly journals X-Ray and Optical Properties of Black Widows and Redbacks

2017 ◽  
Vol 13 (S337) ◽  
pp. 43-46 ◽  
Author(s):  
Mallory S.E. Roberts ◽  
Hind Al Noori ◽  
Rodrigo A. Torres ◽  
Maura A. McLaughlin ◽  
Peter A. Gentile ◽  
...  
Keyword(s):  
Optical Properties ◽  
Binary Systems ◽  
Optical Emission ◽  
Close Binary ◽  
X Rays ◽  
Millisecond Pulsar ◽  
Optical Studies ◽  
Optical Photometry ◽  
X Ray ◽  
Pulsar Wind

AbstractBlack widows and redbacks are binary systems consisting of a millisecond pulsar in a close binary with a companion having matter driven off of its surface by the pulsar wind. X-rays due to an intrabinary shock have been observed from many of these systems, as well as orbital variations in the optical emission from the companion due to heating and tidal distortion. We have been systematically studying these systems in radio, optical and X-rays. Here we will present an overview of X-ray and optical studies of these systems, including new XMM-Newton and NuStar data obtained from several of them, along with new optical photometry.

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